i flflfi‘&% ""‘J i 3 i B R g ey fU , 20 , # i) %«‘%W%&wa@ 3?‘".;5,% e iy“‘*”fi% E"@fi National | Academy of Sciences National Research Council NUCLEAR SCIENCE SERIES The Radlochemlstry of Berylhum *fiffii DL NCTY Wi FHOM [ 2RARY VSR Atomlc' Energy Commnssuon_ COMMITTEE ON NUCLEAR SCIENCE L. F. CURTISS, Chairman " ROBLEY D. EVANS, Vice Chairman National Bureau of Standards Massachusetts Institute of Technology J. A, DeJUREN, Secretary - -~ Westinghouse Electric Corporation H.J. CURTIS G. G. MANOV Brookhaven National Laboratory Tracerleb, Inc. SAMUEL EPSTEIN W. WAYNE MEINKE Cealifornia Institute of Technology University of Michigan . HERBERT GOLDSTEIN - A. H. SNELL Nuclear Development Corporation of - Osk Rldge National Laboratory Amerlca - | E. A. UEHLING H. J. GOMBERG : University of Washington University of Michigan _ D. M. VAN PATTER E. D. KLEMA ' _ Bartol Research Foundation . Northwestern University : ROBERT L. PLATZMAN Argonne Natlonal Laboratory LIAISON MEMBERS PAUL C. AEBERSOLD : W. D. URRY Atomic Energy Commission U. 8. Alr Force J. HOWARD McMILLEN - _ WILLIAM E. WRIGHT Natlonal Science Foundation Office of Naval Research SUBCOMMITTEE ON RADIOCHEMISTRY W. WAYNE MEINKE, Chairman HAROLD KIRBY University of Michigan _ Mound Laboratory GREGORY R. CHOPPIN GEORGE LEDDICOTTE . Florida State University Oak Ridge Natlonal Laboratory GEORGE A. COWAN JULIAN NIELSEN Los Alamos Scientific Laboratory Hanford Laboratories ARTHUR W. FATRHALL . ELLIS P. STEINBERG University of Washington : Argonne National Laboratory JEROME HUDIS PETER C. STEVENSON Brookhaven National Laboratory Universlty of Callfornia (Livermore) EARL HYDE LEO YAFFE University of California (Berkeley) McGlll University CONSULTANTS NATHAN BALLOU WILLIAM MARLOW Naval Radiological Defense Laboratory National Bureau of Standards JAMES DeVOE University of Michigan CHEMISTRY—RADIATION AND RADIOCHFMIST The Radiochemistry of Beryllium By A. W. FAIRHALL Départment of Chemistry Universily of Washington Seattle, Washington May 1960 Subcommittee on Radiochemistry _ National Academy of Sciences —National Research Council Printed in USA. Price $0.75. Available from the Qffice of Technical Bervices, Department of Commerce, Washington 25, D. C. FOREWORD The Subcommittee on Radiochemistry is one of a number of Subcommittees working under the Commjttee on Nuclear Science within the National Academy of Sclences-Rationzl Research Council. Its members represent government, industrial, and university laboretories in the areas of nuclear chemistry and analyticael chemistry. The Subcommittee has concerned itself with those areas of nuclear science which involve the chemist, such as the collection and distribution of radiochemical procedures, the establishment of speclifications for radiochemically pure reagents, the problems of stockpiling uncontaminated materials, the avalla- bllity of cyclotron time for service irradiations, the place of radiochemistry in the undergraduate college program, etc. This series of monographs has grown out of the need for up~-to-date compilations of radiochemical information and pro- cedures. The Subcommittee has endeavored to present a series which will be of maximum use to the working scientist and which contelns the latest available information. Each monograph collects in one volume the pertinent information required for radiochemical work with an individual element or a group of closely related elements, An expert in the radiochemistry of the particular element has written the monograph, following e standard format developed by the Subcommittee., The Atomic Energy Commission has sponsored the printing of the series. The Subcommittee 1s confident these publications will be useful not only to the radiochemist but alsc to the research worker in other fields such as physics, biochemistry or medicine who wishes to use radicchemical techniques to solve a specific problem. W. Wayne Meinke, Chairman Subcommittee on Radiochemistry iid I. II. II1. VI. CONTENTS GENERAL REVIEWS OF THE INORGANIC AND ANALYTICAL CHEMISTRY OF BERYLLIUM ISOTOPES OF BERYLLIUM REVIEW OF BERYLLIUM CHEMISTRY OF INTEREST TO RADIOCHEMISTS ' General Cf;nsiderations Complex Ions of Beryllium Chelate Complexes of Beryllium Soluble Compounds of Beryllium Insoluble Compounds of Beryllium Solvent Extraction of Beryllium Compounds -~ O N W N R Ion Exchange Behavior of Beryllium PROCEDURES FOR DISSOLVING SAMPLES CONTAINING . COMPOUNDS OF BERYLLIUM COUNTING TECHNIQUES FOR USE WITH ISOTOPES OF BERYLLIUM COLLECTION OF DETAILED RADIOCH.EMICAL PROCEDURES FOR BERYLLIUM © @ W e W 10 16 21 22 28 The Radiochemistry of Beryllium™* A. W. FATRHALL Department of Chemistry University of Washington, Seattle, Washington May 41960 I. GENERAL REVIEWS OF THE INORGANIC AND ANALYTICAI, CHEMISTRY OF BERYLLIUM ' - "Beryllium", pp 197-218, Vol. I. of "The Chemical Elements and Their Compounds', N.V. Sidgwick, Oxford University Press, London, 1950. "Beryllium', pp 204-248, Vol. IV of "A Comprehensive Treatise on Inorganic and Theoretical Chemistry', J. W. Mellor, Longmans, Green and Co., London, 1923. Gmelin's Handbuch der A.norgahischen Chemie , System Nr. 26, 8th Edition, - Verlag Chemie G.m.b.H., Berlin, 1930. Chapter 32, pp 516-523, "Applied Inorganic Analysis', W. F. Hillebrand, G.E.F. Lundell, H. A. Bright and J. I. Hoffman, 2nd edition, John Wiley and Sons, Inc., New York (1953), "Beryllium", pp 137-148, Vol. I of ''Scott's Standard Methods of Chemical Analysis", N. H. Furman, editor, fifth edition, D. Van Nostrand Co., Inc., New York, 1939. L. W. Neidrach, A, M. Mitchell and C. J. Rodden, pp 350-359, "Analyti- cal Chemistry of the Manhattan Project'', C. J. Rodden, editor-in- chief, McGraw-Hill Book Co., Inc., New York, 1950. "Non-ferrous Metallurgical Analysis. A Review.' G.W.C. Milner, Analyst 81, 619 (1956). | * Thie report was prepared at the request of the Subcommittee on Radiochemistry of the Committee on Nuclear Science of the National Research Council as a contribution to a proposed master file on the radiochemistry of the elements. . ISOTOPES OF BERYLLIUM Only four isotopes of beryllium are known to exist, those having mass numbers 7, 8, 9 and 10. One of these, BeB, ise completely unstable, breaking up into two alpha parficles in a time less than 10_15 sec. A short-lived isotope of mass 6 has been repor‘l:ed:l but ite existence is doubtful. Of the remaining three, Be’ is the only one which is stable, and constitutes the element. Beryllium is not an abundant element, although its principal mineral, beryl, 3 BeO- Ale 3" 6 SiOZ, is rather wide spread in occurrence. T_l}e average befy]lium content of rocksz is only about 3 ppm, and sea water3 contains only about 5 x 10713 g/ml of the element. . The isotopes of masses 7 and 410 are of interest in that they are both relatively long-lived nuclides. B37 has a half-life of close to 54 day4, decaying by K-electron capture to stable LiT. Of these decays, 12% go to a 0.477 Mev excited state of Li7 and the remainder go to the ground state. 2 The only detectable radiation therefore is the 0.477 Mev y ray, the x-rays of Li being much too soff to be detectable by present techniques. The branching ratio of 12% to the excited state of L17 is uncertain by 5 - 10 per cent, Because of its rather low mass and convenient half-life, Be7 is a nuclide of some interest in the study of nuclear reactions produced artificially in the laboratory. It arises as a spallation producte'“‘10 in the nficlear reactions induced at high energies, and its production 11, 12 Pro- duction of B_e7 by cosmic ray bombardment of the atmosphere has also been observed. 13-15 at lower energies in light elements is of some interest. The heaviest isotope of beryllium, Beio, ie quite long lived, with a half-life of 2.5 x 108y. ‘n decays by p~ emission to the ground state of stable Bio, and in keeping with the long half-life and consequent slow build-up to detectable intensities, the production of Be:10 in nuclear reactions in the laboratory is not likely to be -gtudied radio —chemica_'l.ly; ' Howevef, Bei('J is produced as a spéllation 6,17 - product of cosmic ray action on the atmosphere:l ! 17 and on meteorites, 18 so that its occurrence in nature is of considerable interest to the geochemist. II. REVIEW OF BERYLLIUM CHEMISTRY OF INTEREST TO RADIOCHEMISTS 1. General Considerations In any radiochemical separation of a particular element the chemical procedures which are used are governed in part by the amount of the element which is present in the sample which is being analyzed. Iso- topic carrier, in amounts of the order of milligrama, are often added to the sample to facilitate the separations and to determine the chem- ical recovery of the radioactive species. In the case of beryllium the amount of beryllium carrier which. is to be added to the sample is governed by which of the two radioisotopes is of interest: Be7 can tolerate relatively large amounts of carrier without interfering with the subsequent counting efficiency, whereas samples for counting Be10 should be as weéightless as possible. Fortunately radiochemical procedures for beryllium are available which efficiently will isolate amounts of beryllium r'angi.ng from sub-microgram up to macro - amounts. ' In performing chemical separations with sensible quantities of beryllium present it must be born in mind that beryllium is a very toxic element. Care should be exercised to avoid ingestion of beryllium through the mouth via pipettes or by inhalation of dust or volaetile beryllium compounds. If beryllium —cofita.i.ning solutions are spilled on the skin they should be rinsed off at once. Beryllium is the lightest member of the group II elements. In keeping with its position in the periodic chart it has only one oxidation number, + 2. It is a very good example of the rule that the first member of a group shows a strong chemical resemblance to the second member of the next higher group: in its chemical behavior beryllium more closely resembles aluminum than it does othef members of the group II elements. | Because of the electropositive nature of beryllium, and the existence of only one oxidation number for the ion, exchange between carrier and tracer species presents no problem so long as the Sample cbnta.inin.g them is complefeiy homogeneous. The strong tenciency of bery]lium to o hydrolyse and form colloidal aggrég'atgls. above pH 5 requires El:hat carrier-tracer exchange be carried out in fairly acid solution. - Many of the chemical proper‘l:iéé of beryllium which are important in its radiochemical separations are associated with its ability to form complex ions. These complexes will be treated first, 2. Complex Ions of Beryllium Because of its _s:fiall size and its double charge, the beryllium ion has a strong tendency toward the formation of complexes. Thus the simple salte uniformly have 4 molecules of water of crystallization per beryllium atom, and the hydration of the Be'™ ion forms a basis for understanding the strong tendency toward hydrolysis and the amphoteric properties of this species. Stability constants for several beryllium complexes are given in Table 1. The strong tendency of Be'™ ion toward complex formation shows up in a rather peculiar way by its power to dissolve beryllium oxide. The aqueous solution of any soluble salt of beryllium can dissolve up to several molecular proportions of béry_llium oxide or hydroxide. The reason for this is apparently the tendency to form the complex ion Be(OBe)f , Where BeO molecules have replaced HZO molecules in the aquo complex. Table I. Stability Constants for Beryllium Chelates Chelating Agent log K, log K, log K, " Reference EDTA >3 @ L | 2 acetylacetdne 8.2 7.7 - | 2 9.2 7.8 - 48 7.8 6.7 o 49 oxalic acid ' 4..0 _ ' _ | 2 phosphoric acid 2,54 1.8 | 1.4 L2 The complex formed between Be++ and CZO 4 = , i8 of some interest inasmuch as it is the only oxalate of a divalent metal which is freely soluble in water. It is a good illustration of the difference in chemical behavior of beryllium from that of the remainder of the group II elements. The low degree of ionization of the compound is evidence that it exists as a chelate complex. The complex formed between beryllium and fluoride ion is worth noting. Excess fluoride ion forms the complex anion BeF =, which resembles very closely the sulfate anion. Thus BaBeF4 forms an insoluble precipitate and finds a use in the final precipitation of beryllium in radiochemical analyses. The soluble nature of sodium fluorobgryllate can be used to advantage where mineral specimens are fused with fluorides to render them soluble. 19 The complex is a fairly sirong one, but may be completely destroyed by the addition of excess H3BO3. Beryllium ion is soluble in 10% (N’H4)ZCO3 solution at pH 8. 5-9, presumnably because of the formation of a complex carbonate anion. This property of beryllium has been used in an ion exchange technique for the separation of beryllium from copper and nickel. 20 The f_orma.tion of a BeHZPO 4 complex which limits the phosphatg content of solutions which are to be used in certain cation exchange 2 separations has been reported. 3. Chelate Complexes of Beryllium Bery]liurfi forms nurnerous chelate complexes with a variety of complexing agents. These complexes may be divided into two groups according to whether they are neutral or negatively charged. Neutral complexes are derived either from hydroxy-keto compounds, i.e. p-keto-enois, B-keto-esters and hydroxyquinones, or are a special clags of covalent derivatives of carboxylic acids. A large number of hydroxy -keto compounds have been studied as chelating agents in the colorimetric determination of trace amounts of beryllium. 21 For details of these procedures the original literature should be consulted. There are four chelating agents which deserve special mention because of the important roles which they play in radiochemical separa- tions of beryllium. The first of these which will be mentioned is ethylenediamminetetraacetic acid (abbreviated EDTA), and for the reason that it forms a much stronger complex with many metals than it does with beryllium. Table I lisfs stability constants for a number of metal ions with EDTA. The value of ~ 3.8 for beryllium is sufficiently smaller than those of other common metal ions that _sever_al useful separations may be carried out using EDTA: to prevent interference from other metal species. For example, beryliium hydroxide may be precipitated with ammonia in the presence of aluminum, without the latter precipitating, if excess EDTA is present. Other examples of similar applications will be cited later. A second very useful chelating agent for berylium is acetylacetone. The chelate compound beryllium acetylacetonate, Be(C 5H7OZ)2 melting (108°) volatile (b.p. 270°) golid, ineoluble in water but soluble" is a low in organic solvents. This chelate compound forms the basis for a Table II, Formation Constants of Metal - EDTA Compleces 2" Cation | log K Cation log K Vanadium (IIT) 25.9 Europium - 17. 135 Iron (III) 25,1 _ Samarium 17.14 Indium 24,95 Neodymium 16,61 Thorium 23.2 Zine 16,50 Scandium 23.1 Cadmium 16, 46 Mercury 21,80 Praseodymium 16, 40 Gallium 20.27 Cobalt” 16, 34 Lutecium 19.83 Aluminum 16.13 Ytterbium 19.51 Cerium (III) 15.98 Thulium 19. 32 Lanthanum 15,50 Erbium 18.85 Iron (II) 14,3 Copper 18.80 Manganese _1.4. 04 Vanadyl 18, 77 Vanadium (II) 12. 70 Nickel 18. 62 Calcium 10.96 Dysprosium - 18.30 Hydrogen 10. 22 ~ Yttrium 18. 09 . Magnesium 8.69 Lead 18.04 Stroptium 8. 63 Terbium 17.93 Barium - 17,76 Gadolinium 17.37 - Beryllium 3.8 M7 ¢ vy r e my™t K = —M% M Y 2 In solutions of ionic strength 0.41. Data from reference 22, except for Beryllium, which is from reference 2. solvent extraction procedure for amounts of beryllium as small as the carrier-free tracer (see part III-6), Owing to the volatility of the chelate compound, care must be exercised in reducing solutions of tracer beryllium to dryness .wher'e acetylacetone has been used, in order to avoid lose of the tracer. 23 A third chelating agent which is useful for the isolation of beryllium is the compound thenoyltrifluoroacetone (T'TA). The complex with beryllium is slow to form and to decompose, a property which makes possgible a solvent-extraction separation of beryllium from a number of other cations. 24 The non-volatility of this complex is an advantage over acetylacetone where tracer amounts of beryllium are concerned. The fourth chelating agent of significance to beryllium separations is acetic acid. Beryllium is almost unique in form.:inlg a series of complex compounds with carboxylic acids, of the general formula Be ,O (O-CO-R),. These compounds are non-ionized, soluble in organic solvents, and volatile. The best known of these ig the acetate, 'basic' beryllium acetate, which is formed by treating beryllium hydroxide with acetic acid or acetic anhydride. It is generally employed for solvent extraction of beryllium in radiochemical analyses, although the stability and volatility of the complex (b.p. 330°) permits its isola- tlon by distillation. The second group of chelate complexes of beryllium are those which possess a negative charge. Complexes of this type have been prepared with a number of complexing anions including oxalate, malonate, citrate, Salicylate and sulfate. The complex formed with oxalate has been used in the back-extraction of beryllium acetylacetone from the organic phase in a solvent extraction procedure for beryllium. 23 Complex formation with citrate has been demonstrated and used in the ion exchange separation of the group II metals. 24 The salicylate analogues sulfosalicylate and gentisic acid (2, 5-dihydroxylbenzoic acid) have been used as complexing agents in an ion exchange procedure for separation of berylliumzs and for the spectrophotometric determination of beryllium. 26 Details of the solvent extractiion and ion exchange procedures involving chelate complexes of beryllium will be outlined in parts II1-6 and -7. ' 4. Soluble Compounds of Beryllium- Beryllium hydroxide is a weak base and therefore solutions of its salts are exiensively hydrolysed, forming ions like Be(OH)+ and probably also colloids of the form (BeO)x Be++. Salts of such weak acids as HCN, HZS and HZCO3 are almost completely hydrolysed in water.. The hydrolysis of beryllium solutions leads to the absorption of beryllium onto the walls of the containing vessel. Figure 1 shows the percentage adsorption of Be7 from carrier-free solutions in 0.1 M NaCl buffered with 0. 004 M NaAc as a function of pH. e The pH was varied by addition of HCl or NaOH. Absorptions as high as 20% on glass containers were observed at the higher pH's. ;\3 ¥ S T ¥ ¥ Z 40} 3 fl - a 3o} ] 8 . n 20} GLASS 1 a / < S R . POLYETHYLENE * i | ..—-" g 0 i - 1 1 1 3 4 5 6 ® 9 pH Figure 1. Adsorption of beryllium on the walls of polyethylene and glass vessels as a function of the pH of the solution.- Data of reference 2. Beryllium salts of strong mineral acids such as HNOB, HC1, HBr, HZSO & HCI10O 4 €ic are all quite soluble in water and the salts themselves are usually hygroscopic. The strong tendency of beryllium to form complex ions is shown by the fact that these salts always cry'stallize from aqueous solution with at least 4 molecules of water per atom of beryllium, corresponding to the tetraaquo complex. Soluble complex ions with F_, oxalate, citrate, etc. have already been mentioned (parts III-2 and -3). The action of strong bases such as NaOH or KOH first precipitate insoluble Be(OH)Z-aq, but addition of excess base causes the precipitate to redissolve. At room temperature the solubility of freshly precipi- tated beryllium hydroxide in 0. 39 N, 0.65 N and 1.99 N NaOH is reported to be 0, 06, 0.144 and 0. 66 moles of BE(OH)Z per liter, 21 The solution, however, is unstable. On long standing, or on boiling, beryllium is reprecipitated as a dense crystalline precipitate corres- ponding to the formula 'Be(OH)Z. The amphoteric nature of beryllium hydroxide is a very useful property in radiochemical separations, but whenever a strong base is used to dissolve beryllium from a mixture of insoluble, non-amphoteric hydroxides the mixture should not be subjected to prolonged boiling to effect solution of the beryllium lest the opposite of the desired result be obtained. 5. Insoluble Compounds of Beryllium The most important insoluble compound of beryllium, so far as radiochemical separations is concerned, is the hydroxide. It is precipitéted from aqueous solution by dilute base. Because of the amphoteric nature of the freshly precipitated hydroxide, the best precipitant for beryllium is ammonium hydroxide buffered with NH 4+ ion. The precipitate of beryllium, which begins to appear at around pH 5, is essentially insoluble in an excess of this reagent. Precipitation of beryllium at the methyl red end point (pH ~6) has been recommended. 28 Precipitation of dense, unhydrated Be(OH)Z from boiling alkaline solution has been mentioned above in connection with the amphoteric properties of beryllium. A somewhat similar result is obtained if the complex carbonate of beryllium in ammonium carbonate solution is ‘boiled. In this case there is obtained a white, granular pre-c-ipitate of basic beryllium carbonate of somewhat indefinite composifion. Addition of sodiuni bicarbonate solution to a solution of beryllium also precipitates basic beryllium carbonate. Ignition of the hydroxides or the basic beryllium carbonate results in beryllium oxide. Because of the weakneas of the acid, and the consequent strong tendency to hydrolysis of the resulting compounds, the phosphates of beryllium have a rather complicated chemistry. At lower pH's soluble compounds may be obtained, while at higher pH's Ingoluble precipitates of gelatinous nature, and therefore difficult to identify, are formed. However, an insoluble crystalline precipitate approximating NH 4BePO 4 may be obtained by adding (NH 4:)Z]EIPO 4 to beryllium solutions at pH 5. 5?9 Ignition of the precipitate results in Be ZPZOT This plrocedure is therefore useful in obtaining beryllium in a dense form of known composition. Another method for precipitating beryllium which has some advantages over the others involves formation of the BeF 4= complex anion by addition of excess F ion, followed by the addition of excess Ba++ ion. The solution should be aci-dj_t‘-ied and only a slight excess of Ba++ ion should be used in order to prevent the precipitation of BaFZ. The resultant precipitate of insoluble BaBeF 4 is fine-grained and very difficult to filter through the usual types of dense filter paper. Digestion of the precipitate for 10 minutes prior to filtra- tion helps somewhat, but the filtration problem can be overcome completely through the use of RA -type Mflliporg filters. The compact, dense, and anhydrous precipitate does not require ig’nitidn as do the others mentioned above. This is a distinct advantage in eliminating the health hazard associated with the transfer of ignited beryllium precipitates, which tend to "dust'. The BaBeF 4 Precipitate is much more readily redissolved than ignited BeO, being easily dissolved in a mixture of H3BO3 and HNO3. This is a useful property where further chemical processing is needed to remove unwanted radioactive contaminants from a beryllium sample. Ber:yllium's strong tendency toward hydrolysis, and the insolubility of its hydroxide in near neutral solutions, means that beryllium will tend to co-separate on precipitates when the solution is not at least moderately acid. 29 Almost any precipitate which is forn%ed in a solution containing beryllium at pH~7 will co-precipitate the beryllium to some extent. Particularly useful in this respect _:fi-e gelatinous hydroxides such as those of aluminum and iron. Using Fe(OH), as the co- ' precipitant for beryllium allows the beryllium to be recovered from the precipitate by treatment with cold NaOH solution, or by other means. 6. Solvent Extraction. of Beryllium Compounds The chelate complexes of beryllium with acetylacetone, TTA, and acetic acid, which were mentioned in part III-3 above, lend themselves o . : Obtainable from the Millipore Filter Corporation, Watertown 72, Massachusetts. 10 to very useful solvent extraction procedures for beryllium. These will be given in detail below, Ac e1_:zla.cetone . By shaking or stirring aqueous solutions containing beryllium at pH 4.5 - 8 with acetylacetone a chelate complex is formed which is soluble in organic solvents. Either pure acetylacetone, a solution of acetylacetone in benzene or CCl4 may be used. The use of a small quantity of pure acetylacetone hastens the formation of the chelate complex, after which the complex may be extracted into benzene or other suitable solvent. By stirring a solution at pH 4.5, containing about 1 microgram of beryllium with 4 ml of acetylacetone for 5 minutes, and then adding 20 ml of benzene and stirring for 20 minutes longer, Toribara and Chen found that essentially 100% of the 29 Bolomey and Broido?'3 beryllium is transferred to the 6rga.nic phase. shook 25 ml of 10% acetylacetone in benzene with 25 m] of a solution containing carrier-free beryllium tracer at pH 6 for 2 hours and . found that all but a trace of the activity was exiracted into the organic phase. A great many other metal ione likewige form chelates with acetyl- acetone, and under the conditions described above many of them would also be extracted. The use of EDTA makes the extraction more specific for beryllium. Alimarin and G:lba.lo30 studied the extraction of beryllium acetylacetonate into CCl 47 CHC1 3 butyl alcohol and isoamyl alcohol containing acetylacetone from aqueous solutions containing EDTA and Al, Fe, and Cr, and the divalent ions of Co, Fe, Ni, Mn, Zn, Cd, Pb, Cu, Ca and Mg. When excess EDTA was present only beryllium was extracted into the organic phase. CCl-4 proved to be the best of the solvents which were studied. In strongly ammoniacal solution aluminum and iron acetylacetonates could also be extracted, The organic phase containing beryllium acetylacetonate may be washed with acidified water to remove unwanted impurities without the loss of appreciable amounts of bery].lium23. About 2 drops of 0.1 N HC1 to 25 ml of water makes a satisfactory wash solution for this purpose. The beryllium acetylacetonate complex may be decomposed and the beryllium back extracted into water by shaking the organic phase 11 coritaining the chelate complex with equal volumes of either 10% oxalic acid or 6 N HCl. Bolomey and Broido23 report that 96% of tracer beryllium is back extracted in 2 hours under these conditions. Toribara and Chen29 report that 15 minutes stirring of the organic phase with 5 N HCI] is sufficient to transfer the beryllium to the aqueous phase. Because of the volatility of carrier-free beryllium acetylacetonate, acetylacetone which dissolves in the acid used to 100 80 60 ao | PERCENT EXTRACTION 20 i 1 i L 60 120 180 240 TIME (MINUTES} Figure 2. Rate of extraction of Be by 0. 04 M TTA in benzene at different pH values. Data of Bolomey and Wish, reference 31, back-extract the beryllium should be extracted from the aqueous phase by washing the latter with one or more portions of fresh benzene. The aqueous phase may then be evaporated to dryness under a heat lamp. If oxalic acid is used to accomplish the back -extraction of beryllium it may be sublimed under a heat lamp without loss of activity. 23 With beryllium carrier present the loss of beryllium through volatilization during evaporation of the aqueous phase does not appear to be a problem. 12 a-Thenoylirifluoroacetetone: Thenoyltrifluoroacetone (TTA) is a useful chelating agent for many metals, including beryllium. Bolomey and Wish31 have inves~- ++ 100 - Cu™™ pH 3.40 | Al pH 5.5 & = 8o} - - L < X i @ - X 60t — L 5 i 4 S & 40H - w & | Fell pH 6.38 20K ~ s Al pH 3.4 . 60 (20 80 240 TIME (MINUTES) Figure 3. Rate of extraction of various metallic ions by 0.041 M TTA in benzene at different pH values, Data of Bolomey and Wish, reference 31. tigated the conditions under which beryllium may be separated from a number of other metal cations using this reagent. The complex is rather slow to form and to decompose. In Figure 2 is shown the rate of extraction of beryllium by 0.04 M TTA in benzene at different pH's. The optimum pH for the extraction seems to be about 7, with extraction of beryllium being essentially complete in about 3 hours. The extraction of iron (III), aluminum and copper by 0.01 M TTA in benzene at different pH values is shown in Figure 3. Evidently aluminum is also extracted quite favorably at pH 7, but the extraction of iron is relatively much less favorable at the higher pH. The back-extraction of TTA complexes of Be, Al, Ca, Fe, Zn, Sr and Y from benzene solution made 0.04 M in TTA by concentrated 13 8 PERCENT EXTRACTION 8 & ] 1 l 1 1 - 0 o 20 30 40 TIME (HOURS) Figure 4. Back extractions of several metallic ions with concentrated hydrochloric acid. Data of Bolomey and Wish, reference 31. hydrochloric acid is shown in Figure 4. Back extraction of Ca, Fe, Zn, Sr and Y is complete in 15 minutes. Aluminum requires é hours, and beryllium at least 80 hours, for ''complete' back-extraction. However, the use of 2 parts concentrated formic acid to 1 part concentrated HC1 accomplishes the back-extraction of beryllium in a matter of a few minutes (cf. Section VI, Procedure 12). The solvent extraction method using TTA works equally well for tracer or micro amounts of beryllium. For tracer concentrations of beryllium T'TA has the advantage over acetylacetone that there is no loss of beryllium through volatilization of the beryllium - TTA complex. Acetic acid. When freshly precipitated beryllium hydroxide is evaporated slowly to dryness several times with glacial acetic acid3z, or wfien beryllium acetate is heated to 200° 014, there is formed the chelate compound Be4O(O-CO-CH3)6, '"bagic'' beryllium acetate. It is a crystalline substance ihsoluble in cold water, but readily soluble in most common 14 organic solvents except alcohol and ether. Chlorofarm ig the solvent most commonly employed. The solution of ''basic' beryllium acetate in chloroform is remarkably stable and may be washed free of other cations by extracting with water acidified with HC1 or with water alone. Recovery of beryllium from the chloroform solution may be accomplished by extraction with reagent II‘:[NO3 or by evaporation of the chloroform followed by decomposition of the basic beryllium acetate by heating with concentrated HN03. The preparation of basic beryllium acetate i85 somewhat time- consuming., This disadvantage is offset somewhat by the specificity of ' the procedure for beryllium. 7. Ion Exchange Behavior of Beryllium The strong tendency of beryllium toward complex formation makes possible ite separation by a variety of ion exchange techniques. These are summarized in Table III and discussed in detail below. Cation Exchange Re sins: Separation of beryllium from other cation species by cation exchange may be accomplished in Beveral ways. Beryllium is strongly absorbed on the cation exchange resin Dowex 50 at pH 6 - 8, presumably owing to colloid formationz. At lower pH's beryllium will pass slowly through a cation exchange resin solumn>>. Ehmann and I«.’.ohr:r:ua'a.n28 passed a 1.1 M HCI1 solution containing Be and Al through a Dowex 50 column, a.nd followed it with 1.4 M HCl. At a flow rate of 1 resin volume of eluent per 25 minutes the beryllium was completely eluted with é or 7 resin volumes of 1.4 M HCl. Under these conditions aluminum begins to elute only after 12 to 15 resin volumes of 1.1 M HC! have been passed through the column. Milton and Gru.mmi’cl:34 have used 1.5 M HC1 as eluting agent and Dowex 50 resin to effect a separation of beryllium from the cther members of the alkaline earth family. Their results are shown in Figure 5. | Hond:s:.35 and Kald.ha.na36 have linvestiga.ted the elution of beryllium from Dowex 50 reain by the usge of dilute Ca or Mg solutions. These cations -displace Le from the column, which therefore passes through, 16 but cations such as Al which are more strongly held than the alkaline earths are retained by the resin. | | Complexfi.ng agents, for either unwanted cations or beryllium, have ' been used in the sepa_ration.of beryllium by cation exchange resins. Merrill,Honda and .A.I'J:Lold2 have studied the effect of various complexing Table ITI. Ion Exchange Methods for the Separation of Beryllium Cation Exchange Resin Form Eluting Agent Ions Eluted Ions Retained Reference HR ca 1M HC1 Be Al, Mg,Ca,Sr,Ba 28, 34, 35 HR 0.05MCaor Mg Be 35, 36 HR 0.4 M ozalic acid AL Fe”', U0, Be 2 Th, others HR oxalic acid Al, Fe Be 37 - pH 4.4-5 NH R 0.55 M Amm.lac. Be other alk.earths 34 pH 5 NH 4R. 10%(NH 4)ZCO3 Be Cu, Ni | 20 pH 8.5-9 3+ ++ NaR EDTA,pH 3.5-4.0 Al Fe™ , Mn Be, alk.earths 2, 38, 39 ' heavy metals, others NH R 0. 35 M acetate Be Al, alk,earths, 2 U, others NaR. acetylacetone Be’ Al, alk, earths 2 PH 5 U, others N".E[4R 0.02 M sulfosali- Be Cu, U, Ca 25 cylic acid pH 3. 5- 4.5 Anion Exchange RC 204 0.4 M oxalic acid Be Al 28 0.15 M HC1 RCit i Mamm.cit.pH 8 Be other alk.earths 24 RC1 various conc.HC1 Be many transition 40-42 elements RC1 13 M LiCl alk. metals, Be 43 Mg 16 INTERSTITIAL COLUMN VOLUMES 2 3 4 6810 20 30 40 €0 80100 I III—II'T I —l_llfllll 5 o Ca NO Ba TO 650 ml CONCENTRATION OF SOLUTE (mg/ml) o { o L1t 1 1 20 3040 6060100 200 300400 600 ELUATE VOLUME (mi) 0 @k 5 Figure 5. The separation of beryllium, magnesium, calcium, ~ and strontium by cation exchange using 1.5 M hydrochloric acid eluant. Dowex 50 column 1.1 x 8 cm, flow rate 1.0 ml/min, T ~ 60° C. Data of Milton and Grummitt, reference 34. agents on the uptake of beryllium by Dowex 50 resin. Be7 was used as a tracer in these experiments which were conducted at room temperature, 23 - 25° C. They define the distribution coefficient of Be, Kd’ to be Be7 adsorbed / g resin Ky = 7 Be remaining / ml solution at equilibrium. For purposes of normalization they also define the distribution coefficient, D, to be Be++ adsorbed /g resin Be7 remaining /ml solution D= measured in the absence of complexing agents. In0.1 M Na+, and with the resin in the sodium form, D was | measured to be 700 for 200-400 mesh resin and 830 for 50-100 mesh resin. In 0.1 M H+, and with the resin in the hydrogen form, D was 17 measured to be 1870 for 50-100 mesh resin. The value of D was found to vary with the concentration, C, of the monovalent cation in the,solution, and in the neighborhood of the concentrations which were used D varied K as _1 . Values of the quantity _ d are shown in Figure 6 plotted 2 D against the concentration of complexing agenti for several cases. Stability constants were calculated for the several complexes from these cation exchange data and are given in Table I, page 4. Because certain unwanted cations may form much sironger complexes than does beryllium, the use of complexing agents such as EDTA or oxalate can be quite efiective in isolating beryllium from a mixture of 1 1 I 1 1 I I I 1 I 1 ! .00 ] 0.10 — Xd D 0.01 ] 0.001 1 1 1 i " 4 3 CONCENTRATION OF COMPLEXING AGENT O« EDTA(Y*~},0.08M Nat-NaR D« OXALATE (aA=),0.1 M. Né"NaR X « ACETYLACETONE {A™),0.1M + = PHOSPHORIC ACID (A™) 0.C3 M H*-HR . Na™= Na R . ® = H PO~ (A), 0.IM Ne'-NaR N = OXALIC ACID(A™),0.IM H'-HR A= OXALIC ACID(K"),0,IM Na'~Nag R Figure 6. Uptake of beryllium by Dowex 50 resin from solutions containing various complexing agents, Data of Merrill, Honda, and Arnold, reference 2. 18 cations. EDTA is especially useful in this respect, particularly in the separation of beryllium from iron and aluminum. Table IV showe the small uptake of aluminum by Dowex 50 when excess EDTA is present. 2 Using Amberlite IR-120 resin in the sodium form Nadkarni, Varde and Athavale 38 found that from solutions containing excess NaZHZ EDTA at pH 3.5 beryllium was absorbed by the resin while aluminum, calcium and iron passed through the column. If HZOZ was present titanium also passed through the column unabsorbed by the resin. Oxalic acid is useful for the separation of beryllium from such ions as Fe+3, A1+3, U02+2, and Th+4. Oxalic acid, 0.4 M solution, may be used to elute these ions while beryllium is retained on the column. 2 Ryabchikov and Buk.htiarov37 report the separation of beryllium from iron and aluminum by the use of oxalate at pH 4.4, Iron and aluminum pass through as complex ions while beryllium is retained on the column. The separation of beryllium from magnesium and the other alkaline Table IV. Uptake of Aluminum by Dowex 50 from Solutions Containing Excess EDTA Volume of solu- pH before pH after Al absorbed tion pessed® passing passing (mmole /g resin) 50 2,79 : -- 0.19 30 _ 3.40 3.24 0.007 30 3,62 3.78 0.003 50 3.52 3.64 0.0026 8 sample solution: 0.22 M Na' + 0.4 M AIY + 0.041 M excess EDTA +S0,7; CaCO, added to adjust pH. Data of Merrill, Honda, and Arnold, reference 2. earths by means of ammonium lactate hag been deacribed by Milton and Grummitt. 34 Using 0.55 M ammonium lactate at pH 5 as the eluant, a flow rate of 1 ml/min., and a Dowex 50 column maintained at a temper- ature of 78° C, beryllium was eluted from a 1.1 x 8 cm column in less than 2 interstitial column volumes. This was considerably in advance of magnesium, which began to elute at around 2.5 interstitial column volumes, 19 The use of palicylate analogs for selective elution of beryllium adsorbed on a Dowex 50 reain column has been reported by Schubert, Lindenbaum and Westfall. ?'_2' Using 0.02 - 0,410 M sulfosalicylic acid at pH 3.5 - 4.5 beryllium is selectively eluted while Cu.H-,l uo t and Ca++ 2 iong remain firmly on the column. If iron is also adsorbed on the column it can be eluted before the beryllium with 0.4 M sulfosalicylic - acid at pH 2. 1, When 0.1 M gentisic acid at pH 6, 0 is used to elute a Dowex 50 column (H - form) containing adsorbed Ca++ and Be++ ions the beryllium - comes off in a sharp band, beginning when the pH of the effluent reaches 1.9, reaching a maximum at pH 2.-74 and complete when the effluent reaches pH 5. 60. 25 Under these conditions calcium is still retained on the column. Starting with 150 ml of solution containing 1.1 g of Ca.Clz, 5 pg of Be, and 0.1 M in sulfosalicylic acid at pH 4.5, these authors passed the solution through a column containing 15 g of air —dried Dowex 50 resin which had been equilibrated with 0.4 M sulfosalicylic acid at pH 4. 5. Beryllium pasaed completely through the column with the aid of 70 ml of wash solution (0.1 M sulfosalicylic acid at pH 4. 5) while calcium was completely adsorbed. | ' Rapid elution of beryllium adsorbed on a cation exchange resin which has been washed free of unwanted cations may be accomplished by sirong (> 3 M) HCI, 33, 38, 44 or by a solution of 0.5 M NaAc and 1M H.Acz. In the latter case 0.5 - 1,5 column volumes of effluent contain all the beryllium, which may be recovered as Be(OH)2 by adding NH 4OH'?'. Anjon Exchange Resing: The use of anion exchange resins in the separation of metal cations implies the formation of negatively charged complex ions, either of the depired element to be separated, or of unwanted impurities. As an example of the latter, in hydrochloric acid solution beryllium does nof form a complex with chloride ion of sufficient strength to be absorbed on Dowex I resin. 45 A great many other metal ions do, however, form chloride complexes which are absorbedl by Dowex I resin, 40-42. Beryllium :fiay therefore be separated from these elements by simply passing the solution in hydrochloric acid of appropriate strength 20 through a Dowex I resin column. Unwanted ions will be adsorbed while beryllium will pass through unadsorbed. Even though beryllium shows negligible adsorption onto Dowex I resin from 12 M HCI solutions, it is interesting that there is adsorption of beryllium from 13 M LiCl -soluti'on. 43 With a distribution coefficient of 8 in this solution (Be adsorbed per Kg resin/Be remaining per liter of solution) beryllium could be separated by anion exchange from non- adsorbable elements such as alkali metals and magnesium by this technique. Anion exchange separations of beryllium based on the formation of negative complexes of beryllium do not appear to have been extensively used. Ehmann and Koh::nzmz'8 have used the oxalate complex of beryllium to effect radiochemical purification of beryllium. Beryllium chloride solution, after evaporation to dryness was taken up in 0.1 M HZ.CZ.O4 - 0.15 M HC1 (pH = 0. 9) solution and passed through a 4" x 1/2" column of Dowex I resin at a flow rate of 1 ml/min. Elution was by the same solution, which effected the eleution of beryllium in 5 resin volumes. Nelson and Kraus’® studied the peparation of the alkaline earth elements by anion exchange using citrate solutions and Dowex I resin. Beryllium is more sirongly absorbed than the other Imembers of the family at low citrate concentrations, although at citrate concentrations greater than about 0.1 M magnesium is more strongly absorbed than beryllium. Effective separation of beryllium from Ca, Sr, Ba and Ra may be accomplished by this technique, but the sepax.-at'ion from magnesgium is less satisfactory. Using 1 M (NH 4) 3Cit at pH 8 beryllium comes off first, but the last portion of beryllium will be contaminated with magnesium. Alternatively, using 0.2 M (NH 4)3Ci‘l: at pH 4. 3 magnesium comes off first but tdils badly and contaminates the beryllium as it is eluted from the column. IV. PROCEDURES FOR DISSOLVING SAMPLES CONTAINING COMPOUNDS OF BERYLLIUM Inasmuch as the common salts of beryllium, the chloride, fluoride, nitrate, sulfate etc., are freely soluble in water, the problem of 21 dissolving the sample is that of rendéring soluble the matrix material in which the beryllium is imbedded. For the gpecial case of beryllium . metal itself the best solvents are hydrochloric or sulfuric acid. The metal also dissolves in alkali hydroxide soluticns owing to the amphoteric character of the element. Nitric acid, either concentrated or dilute, is not a suitable solvent for it renders the metal passive. The radioberyllium content of meteorites and of varicus sediments and rocks is of considerable interest to the geochemist. F¥or iron meteorite material aqua regia is the solvent commonly employed. For siliceous materials HF is the appropriate solvent; the silica is volatilized, eliminating a bulky and otherwise troublesome component from the sample. At the same time the beryllium forms a complex with fluoride which should ensure good carrier-tracer exchange. However, care should be taken to decompose the fluorides, and the beryllium complex, before proceeding with the separation. The BeF 4= complex ion is similar in behavior to the SO, anion. The best method for destroying the BeF 4 complex is to trgat the sample with HBO 3 after the bulk of the fluorides have been decomposed by treatment with HZI\TO3 or HZSO 4 . | Because of the formation of BeF 4_ complex ion with fluorides, the use of a NaF fusion to render soluble the beryllium in siliceous samples has been reported by Ru.mlig. V. COUNTING TECHNIQUES FOR USE WITH ISOTOPES OF BERYLLIUM Counting of Be7 The only ohservable radiation from BeT is a y ray of 0. 477 Mev energy emitted in ~ 42% of the decays (see Part II). Scintillation counting is the obvious choice for detection of these y rays. Because of the possibility that other y-emitting species, or |3+—emi1:ting 'species which would give rise io 0.54 Mev annihilation quanta, might be present in the sample the counting of Be7 can be done with assurance only if a y ray spectrometer 1s available for exemining the y ray spectrum from the sample. In addition to the criterion of radiochemical purity, i.e. the beryllium sample for counting must show only a 0. 477 Mev ¥ ray, 22 one may also require that the sample emit no particle radiations, since Be7 emits none. In particular; this is a requirement when Be7 is produced in nuclear reactions in the laboratory. As discussed in Part 1I, production of §~emitting Beio in significant intensities in these instances is negligible. For the study of Be7 produced in nature by cosmic ray action, Beio is also known to be 1:>roc1uLceciié)—fi'8 S0 that a low intensity of § emission from Bei0 is to be expected. A third criterion of the radiochemical purity of a beryllium sample is the half-life for decay of the sample, which should be 54 day. Because of the long time lapse required to egtablish a half-life of this magnitude, particularly for samples of low activity, it is generally desirable to establish the radiochemical purity of the sample by other means. Where other means of establishing the identity of a radioactive species are lacking, the constancy of the specific activity {counting rate per mg of sample) of the sample when put through a number of radiochemical purification steps is usually sufficient to demonsirate that the activity is isotopic with the element of the sample. The most difficult situation for extablishing the presence of Be7 in a radiochemically pure condition in a counting sample arises when the intensity is very low, of the order of 30 ¢/m or less, in which case it may be very difficult to obtain an accurate 7 ray spectrum or to detect low intensities or particle-emitting impurities. One must then fall back on the constancy of the specific activity as a criterion for establishing the identity of the activity which is being counted. One must therefore have a very reliable and specific radiocchemical procedure for beryllium in order to minimize the possibility of having a radioactive contaminant in the counting sample. In this regard it is worth drawing attention tc the nuclide "1‘12029 which decays by K and L capture to HgZGZ with the emission of 0. 44 Mev y rays. Is y ray energy is so close io that of Be7 that the chance of producing this species by nuclear reactions on mercury and lead isofopes should not be ocverlooked. . The clogeness in energy of the ¢ ray of Be7 to 0. 51 Mev annihilation quantz makes rather easy the determination of absolute disintegration rates of Be7 samples. Solutions of the §5+—emitting species Naz which have been accurately standardized for their sbsolute specific 23 activities are commercially available for calibration purposes. Provided the source is sufficiently thick to stop all positrons, the rate of emission of 0.51 Mev annihilation quanta will be just twice the positron emission rate of the source. The éource may then be used to determine the detection efficiency of the scintillation detector for 0. 51 Mev quanta, which will be very close to the detection efficiency for 0.477 Mev quanta. N’a22 ‘has also a 1. 28 Mev y ray which complicates matters somewhat, since this y ray will also give rise to some pulses equivalent in energy to those arising from 0. 51 Mev quanta. In 6rder to get around this difficulfy it is necessary to determine the detection efficiency of the scintillator in the neighborhood of the 0. 51 Mev photo peak. This is best done using a ecintillation spectrometer with a window which can be opened to straddle the photopeak. Cdntributions to the observed counting rate within this window from the 1,28 Mev y ray of a Na>? source may be estimated in the following way. The counting rates in the energy region a little above and a little below the 0.5%1 Mev photopeak is first measured using a rather small window to obtain the counting rate per unit window width in these two regions. These counting rates will be aJinost entirely due to 1. 28 Mev quanta, and can be used to estimate the contribution to the counting rate in the region of the 0. 51 Mev photopeak by ihterpolation between them. In a typical 2 inch well-type scintillation detector the contribution from 1.28 Mev quanta to the counting rate in the 0. 54 Mev photopeak amounts to about 17% of the total. ' Having established the counting rate, R, of annihilation quanta which fall within the window of the spectrometer, the detection efficienty, E, of the spectrometer with the window straddling the 0. 54 Mev photopeak is given by ' R E—fif& D is the positron emiasion rate of the source and fa is a factor to correct for absorption of 0. 51 Mev quanta within the source. Provided the source is not too thick, fa is not a very significant factor, and can be made to cancel a similar correction factor for beryllium if the Naz'2 sample is about the same thickness as the beryllium samples. 24 Having determined the counting efficiency of the scintillator for 0.54 Mev quanta, the base line of the spectrometer is shifted downward an appropriate amount so that the window of the spectrometer straddles the 0.477 Mev photopeak of Be7. The same window width should be used as for the 0.54 Mev annihilation photopeak, in which case the detection efficiency of the spectrometer is very close to E. For a typical 2 inch Weil—type scintillation detector E has a value of about 6 percent for 0.5 Mev quanta. Restricting the energy interval in which pulses wili be counted o the photopeak resulis in an appreciable loss in counting rate of the source over that which could be obtained if a window were not used, With strong Be? source the disintegration rate of the source could be determined as outlined above and the sample used to determine the counting eificiency of a scinfillation counter which counts all pulses above a minimum threshold. This is satisfactory for sources with counting rates in excess of a few hundred counts per minute. With very weak sources, however, counting with a2 window is usually to be preferred because it resulis in a more favorable sample-to~-background counting ratio. | Counting of Be10 Because of the long half life of Beio, and the fact that this nuclide is likely to be of importance only in nuclear reactions produced through the action of cosmic rays, the disintegration rate of any sample containing Béio will be very small indeed. When the low B decay energy of 0.555 Mev is congidered also, the counting of Beio becomes a formidable task. Evidently Geiger or proportional counting of thin samples in some type of low level counter is called for. Since procedures are available for isolating beryllium in carrier- free amounts, counting samples which are very thin can be prepared. Presumably the thickness of the final sample is limited by the beryllium content of the starting material which is analysed. If such a carrier-free separation were attempted, the recovery efficiency of Beio could be obtained by measuring the recovery of a Be7 "spike" which was added at the beginning of the analysis. Of course the amount of B(—:f7 spike to be added should be chosen so that its counting rate does not overwhelm that due to Beio., The much lower counting efficiency 25 of Be'? v radiation in a Geiger or proportional counter means that roughly 100 times the disintegration rate of Be7 cofi:pared with Be10 may be present in the sample before the accuracy of counting of Be10 is impaired. The identity of Be10 in a sample from the carrier-free separation of beryllium could be determined in a manner similar io that which is 10 used when carrier is present. The constancy of the ratio of the Be counting rate to that of Be7 tracer, when repeated chemical separations are performed on the sample, should suffice to demonstrate that any p activity is due to Beio. Because of the complexity of the chemical separation which may be required in some instances for isolating beryllium in a pure condition, or in high yield, it may be necessary to add beryllium carrier. In this case tfie final sample for counting will have an appreciable thickness, and the counting efficiency will be somewhat impaired. | Two systems for counting moderately thick Beio samples have been described. The earlier of theseib uses a thin wall cylindrical counter of the type described by Sugihara, Wolfgang and Libby. 46 The beryllium counting sample is mounted on the inside walls of two hemi-cylinders by deposition from a slurry of the sample in alcohol. The hemicylinders are then placed In close contact with the thin wall counter. Under these conditions the geometry of the counter is about 40%. To reduce background the coumter is surrounded by a ring of anti-coincidence counters. Because the sample area can be quite large under these conditions the sample can be made quite thin. However, correction for gself-absorption of the radiations is necessary, and may be determined by the method of Suttle and Libby. 47 Figure 7 shows an absorption curve in polyethylene of the radiations from Be‘10 using such a counter. 16 The measurement of the absorption curve of the radiations from a beryllium sample serves as é check on the radioactive purity of the sample, and the data may be used' to calculate the self absorption of the radiations by the sample, Ehmann and Kohmanza have recenily described a counting procedure for measuring very low levels of Beio and other naturally-occurring ' radioactive species. They use a side-window counter having a window 26 = [ g 1.0 -_ j W a9 » g 08 - 5 or} { £ o.e o w - dJ 0.8 o t 2 0.4 E g 0.5 - 1 e el -l 2 1 t 0O W 20 30 40 60 60 70 - SAMPLE THICKNESS (mg/cm*) Fig. 8. Relative counting rate per unit weight of sample for samples of Bel0 in BeO of | O 10 200 30 40 5 € 70 ABSORBER THICKNESS (mg/tm’) e ———— e L fixed specific activity vs, the sample thicknesses. Fig. 7. Absorption curve of BelO in Data of Ehmann and Koh- olyethvlene in close cylin- potyethy Y man, reference 28. The drical geometry. Data of ' _ : extrapolation to zero - Arnold, reference 16. . _ thickness was made from data of Nervik and Steven- son, reference 47, area sglightly over 6 cmz, with a surrounding shield of anti-coincidence counters. The sample is placed in a dish close to the window of the _ counter in a geometry close to 40%. 'This system is inherelntly simpler to construct and operate, although counting samples will generally not be quite so thin as in the thin wall counter described above. However, self scattering in moderately thin samples helps to overcome the effects of self absorption as shown in Figure 8. 27 VI. COLLECTION OF DETAILED RADIOCHEMICAL PROCEDURES FOR BERYLLIUM ' PROCEDURE 1 Separation of beryllium from stone meteorite material Source - _W. 'D. Ehmann and T. P. Kohman, Geochim. et Cosmochim. Acta 14, 340 (1958). Procedure: Step 1, .Step 2, Step 3. Step 4. ' Rinse the specimen with acetone to remove any laquer which may have beén used to preserve it. Grind a 50-150 g sample of the Speci.’men to a find powder using an électrolytic iron sheet and iron roller. Transfer this fine powder to a 1 liter polyethylene beaker which is placed in a waterbath at room temperature. Dissolve the sé.mple in a hood by the cautious addition of 48% hydrdfluoric acid. (Note 1) ‘About 5 ml of hydrofluoric acid per gram of sample is used. Allow the mixture to | gtand at room temperature for 3-4 hours with occasional stirring. . _ : Heat the mixture on a water bath at 100° C, with occasional stirri.ng,-until the mixture goes just to dryness. Add 50 ml of HF to the residue and aé‘ain evaporate to dryness.' Add -' 50 ml conc. HN03 to oxidize iron and again reduce to dryness. Dissolve the residue in 100 ml of conc. HC1 and again evaporate to dryness tb femove.excess HF and HN_O3'. Repeat the evaporation with 100 ml of conc. HCI. Dissolve the residue from the evaporation in 1 1. of 9-10 M HCl. Filter through a funnel with fritted glass disk to remove ‘insoluble residfie which is usually found in trace amount. Add an accurately known amount of Be carrier to the solution and transfer the solution to a 2 1. separatory funnel. 28 SteE 8. . Step 9. . Step 10, Step 11. Step 12. SteE 13, SteB 14, PROCEDURE 1 (CONTINUED) Extract iron with consecutive 306 - 400 ml portions of isopropyl ether which has been saturated with 9 M HC1. Three of four extractions are usually sufficient. Wash the combined ether extracts three times with 50 ml portions of 9 M HCl, combining the washings with the extracted-aqueous phase. Reduce the volume of the solution to about 250 ml on a hot plate. To this solution add 500 ml of 12 N HC1, making the solution approiimately 10.M In HC1. Pass the solution through an ion exchange column approximately 2.5 cm in diameter containing 200 - 250 ml of Dowé_x 1, X-10, 100 - 200 mesh ion exchange resin. Adjust the flow rate 1o approiimately'i ml/min, (Note 2) Wash the column with 500 ml of 40 M HC1 and commbine the eluates. Reduce the volume of the solution to 300 ml on a hot plate. Add NH ,OH to pH 7 to precipitate Al and Be hydroxides. Filter through a Millipore HA filter in a 6.5 em Buchner funnel and wash with 25 m] of 5% NH ,C1 adjusted to pH 7. Dissolve the precipitate in dilute HC1 and reprecipitate and filter as in Step 9. Repeat the precipitation fithir_d time. Transfer the precipitated Al and Be hydroxides on the filter paper to a 250 ml beaker. Add 25 ml of 8 M NaOH and 10-20 mg of Fe (IM) carrier. Macerate the filj:er paper and heat the mixture to boiling. Filter the warm slurry through a funnel having a 6.5 cm fritted glass disk. | Wash the solids in the funnel with a small amount of hot water, combining the washings with the filtrate, Dilute the solution to 250 ml with distilled water and treat the solution with 6 M HC1 io precipitate Al(OH)3 and Bca-,(OH)z at the methyl red end poini;. Filter off the precipitated hydroxides and redissolve them in dilute HC1. Reprecipitate the hydroxides with NH ,OH at the 4 methyl red end point. Filter the precipitate and again repeat - the precipitation at the methyl red end point. Dissolve the precipitated Al and Be Bydroxides in the minimum - amount of 6 N HC] necessary to yielldh- complete solution. Dilute - the solution.to approximately 50 ml with distilled water and 29 Step 15. Step 16, Step 17. Step 18. - PROCEDURE 1 (CONTINUED) adjust the acidity to 1.4 M HC1 by dropwise addition of 6 M HCI, using a pH meter and standard 4.1 M HCI solution for comparison. Pass the solution through a 25 ml resin volume of Dowex 50, X-8, 50-100 mesh ion exchange column about 41/2 inch in diameter and 10 in. lo-ng.' Adjust the flow rate to 1 ml/min. After the solution has passed through the column elution is continued with 1.1 M HC1 until Be is completely eluted, usually in about 6 or 7 resin volumes. (Note 3) Evaporfite the effluent containing Be to dryness on a steam bath. Dissolve the residue in 25 ml of 2 M HCl, Pass the solution through a 5 ml Dowex 1 ion exchange column 2 in. long and 1/2 in. in diameter. After passage of the sample solution the column is washed with 10 ml of 2 M HC1 and the washing is added to the first eluate. Pb+2 is adsorbed in the column. Evaporate the eluate containing the beryllium to dryness. ~ Dissolve the residue in 25 ml of 0.4 M H,C,O, - 1.5 M HC1 S22 4 (pH = 0.9). Pass the resulting solution through a Dowex 1 column 4 in. in length and 1/2 in.- in diameter at a flow rate of 4 ml/min. Continue elution with 0.4 M H,CO, - 0.45 M HCI until 5 resin volumes (about 50 ml) of the eluting solution has passed through the column. Residual Al is "adsorbed on the column while beryllium passes through. Treat the eluate from the column with NH 4OH to pH~ 7 to precipitate Be(OH),. Filter the precipitate on Millipore HA filter paper in a 6.5 cm Buchner funnel. Ignite the precipitate at 1000°C, weigh the BeO to determine a chemical yield, and mount the sample for counting. (Note 4) Recycle Procedure: Step 1. Transfer the BeO from the counting tray to a beaker and treat it with a mixture of 15 ml conc. HNO, and 15-ml 9M HZSO 4+ Boil the mixture on a hot plate for 4 hour, or 30 Step 2. Step 3. Step 4. Step 5. Step 6. Step 7. PROCEDURE 1 (CONTINUED) until the solution is complete. Dilute the solution to 400 ml with distilled water. | Add about 10 mg Fe (III) carrier to the soluticn and precipi- tate Fe(OI—I}3 and Be(()H)2 with NH4OH at pH ~ 7. Filier the precipitate on Whatman No. 31 fiiter paper ina 6.5 cm Buchner funnel. _ . Transfer the filter paper and hydroxides to a 250 ml beaker and treat with 15 ml of § M NaOH solution. Heat the solution 1o boiling and filter the warm slurry through a funnel having a 6.5 cm fritted glass disk. Wash the residue with 40 ml of & M NaOH adding the washings to the filtrate. ' Dilute the combined solutions to 100 ml and add 6 M HC1 to precipitate Be(OH)2 at pH ~ 7. Filter this precipitate on Millipore HA filter paper in a 6.5 cm Buchner funnel. Dissolve the precipitate and r’ei)recipitate twice with NH 4OH at pH ~ 7 to assure removal of the Na+ present, Dissolve the final Be(()H)‘2 precipitate in 25 mi of conc, HC1 and pass the solution through a 410 ml Dowex 4 anion exchange column 4 in, long and 4/2 in. in diameter. Rinse the column with 20 ml of conc. HCI after introduction of the sample. _ Reduce the combined effluents from the column to 40 ml by evaporation on a hot plate. Add 20 mi of distilled water to make the resulting soiution about 2 M in HC1l. Pass this solution through a 10 ml Dowex 1 column and rinse the column with 20 ml of 2 M HCl,V Combine the effluents frém the column and evapcrate them to dryness, Disgolve the residue in 25 mlof 0.1 M H_ C_O 27274 0.45 M HCI and proceed as from Step 17 in the Procedure. (Note 5). _ NOTES 1. Violent effervescence is prevented by the use of the water bath for cooling and the slow addition of the hydrofluoric acid. 31 PROCEDURE 1 (CONTINUED) . . +6 44 4 _.+ : . Residual Fe+3, Co+2, Cr+ y U Pa.+5, Po+ , Bi 3 and about thirty : . +2 +3 other elements are held in the column (log D> 1); while Ni -, Al -, '_Ca+2, Th+‘.4, , Pb+2,' Ra+2, and Ac? of the elements of interest pass freel;)lr through- (no adsorption). The alkali elements and the other ' alkaline earth elements are also not absorbed. Al-l-3 is held on the column, but would start to elute at about 12 to 15 resin volumes of 1.1 M HC1. _ It is recommended that a dust mask be worn to prevent the inhalation ~ of very toxic BeO dust. ' | The chemical procedure as given is not completely satisfactory inas- much as the initia.l.radioacti'vity usually decreases on recyéling. _ The initial chemical yield someflmes exceeds 100 percent, indicating _incoi:nplete separat'ion from bulk consfituents, although a given - specimen of stoney meteorite might contain appreciable amounts of beryllium, It éppeara that at least three recyéles may be necessary - to get rid of all contaminating activities and inert impurifies. The introduction of an extractiofi step using acetylacetone, following thé . directions given in Section IIIJ:', would probably brove of value in eliminating these difficulties. Such an extraction step could be introduced after step 13, using an excess of EDTA to hold back Al, or the extraction could be carfied out following Step 17 after precipitating Be with NH 4OH. PROCEDURE 2 Separation of beryllium from iron meteorite material Source - W. D. Ehmann and T. P. Kohman,l Geochim et Cosmochim. Acta 14, 340 (1958). Procedure ‘Step 1. Wash the sample, which may weigh from 100 to 150 g, with distilled water and acetone to remove terrestrial dirt a.nd any lacquer which may have been used to preserve the gpecimen. 3z Step 2. Step 3. SteB 4, Step 5. Step 6, PROCEDURE 2 (CONTINUED) . Place the sample in a 2 1, beaker and treat with consecutive. 200 ml portions of aqua regia. Afier reaction has ceased pour off each portion into a separate beaker. Continue thig. - ifreatment until the specimen is completely dissolved. To the combined solutions add 25 ml of conc. HNO3 to ensure oxidation of iron (II). Evaporate the solution to near d‘ry'nes_s with several 500 ml portions of conc. HC1 to remove excess H_NO3. | o To the small volume from the last eVa_poration add sufficient 9 M HCI1 to brifig the volume up to 1 1. Filter the solution through a Whatman No. 50 filter paper in a Buchner funnei. A small residue, possibly graphite, may be discarded. Add beryllium carrier and carriers for other radioelements which it may be deeired to sepa.raté. Transfer the solution toadl. _s-ep'aratory funnel a.nd_exu'aét iron with consecutive 300-400 ml portiona of isopropyl ethelr s#turated with 9 M HCI. Three or four extractions are usually sufficient. Combine the ether layers and wash them three times with 50 ml portions of 9 M HCl. Add these washings to the aqueous phase. Proceed as from Step 8 of Procedure 1 for separating beryllium from stqfie meteorite material. (Notes 1, 2). _ - NOTES 1. The chemical yvield of heryllium sometimes appears to exceed 100 per - cent. However, the weight of BeO often decreases apbreciably on recycling, i.mplying that the appa.rént extra yield comes from 'J'.ncomplete separation from bulk constituents rather than from béryl]_ium present in the meteorite, - 2. See Note 5 of Procedure 1. 33 PROCEDURE 3 Separation of beryllium from deep-~sea sediments (I). Source - P. S. Goel, D. P. Kharkar, D. Lal, N. Narsappaya, B. Peters, and V. Yatirajam, Deep-sea Research 4, 202 (1957). Core samples of ocean-bottom sediments weighed between 66 and 139 grams when rdry. Beryllium was recovered from them without addition of beryllium carrier by the following procedure. The recovery efficienty was determined to be 80 & 10% by spiking some sample 7 sediments with Be {racer before the analysis. Procedure: Step 1. To the dry sample add 500 m] conc. HC1 and 250 ml conc. . HNO 3.‘ Heat to destroy organic matter and to drive off the acid. Destroy nitrates by repeated evaporation with conc. HCIL. - Step 2. Boil the semi-dry residue for 45-20 min. with conc. HCI, dilute with 300 ml water and heat the mixture to boiling. Allow the solids to settle and decant the solution. Wash the solid residue with 100 ml portions of 6 N HC1I until free of iron. Combine the solutions (Solution Li). ‘ Step 3. Boil the solid residue with 120 g NaOH in a glazed silica dish for 15 min and filter off any undissolved solid (Solution M). Fuse the solid residue with five times its weight of Na,CO, and dissolve the melt in 100-150 ml of water. Filter off and discard any insoluble residue (Solution N). Step 4. Combine solutions L; M and N and heat to drive off COZ' Add ammonia to pH 8 to precipitate insoluble hydroxides. Filter the mixture, discarding the filtrate. Dissolve the precipitate in 200 ml conc. HCI. Step 5. Evaporate the solution to dryness twice with additions of HCI1 to precipitate silica. Boil the precipitate with 400 m] of 6 N HC1 and filter (Solution O). Step 6. Moisten the silica residue with H,SO, and heat with 48% HF to remove SiOz. Fume any remaining residue with HZSO4, ignite it and then fuse it with NaZCOB' Dissolve the melt 34 Step 7 . Step 8. Step 9. Step 10. Step 14, Step 12. Step 13. PROCEDURE 3 (CONTINUED) in HCI1 and filter. Combme the filtrate wrr.h Solutlon O _ _ Add ammonia to Solution O to bring the pH to 8. Filter the precipitated hydroxides and discard the filtrate. Dissolve . ' the precipltate in 500 ml 6 N HCI. Extract Fe(IIl) from the solution by shakmg with 1 liter | of ether. Concentrate the aqueous phase to 150 ml, add 15 g NH,C1 and cool in an ice bath. Add 300 ml of ether and pass in HC1 gas. Filter off the precipitate of Al and Ti chlorides. Evaporate the filirate to 50 1l volume. Adci 8 g disodium EDTA to tfie solution é.nd adjust the pH to 4.5-5.0 by the addition of dilute NH OH. Add 2.5 ml _acetylacetone a.nd shake for 5 minutes. Extract beryllmm from solutlon with four 100 ml pOI“thIlS of benzene, shaking the 1_'_nn_rture for 10 minutes each time. : _ C._ombine the benzene layers and back-extract beryllium by shaking with four 175 ml portions of 6 N HCI. Combine the HCI extracts and evaporate the solution to dryness. Destroy any organic matter by evaporation with _afiua regia. Take up the residue from the evaporation in about 40 mlof 1 N HCl _ Cool the solutlon in an ice bath and add 10 ml of 6% cupferron solution. Extract the mixture with three 40-ml portions of CHCls; and discafd the Qrga.n_jlc:phase_. Evapo_rate the -agueous phase to dryness and decompose organic matter by evaporation wrth HNO _ . Decompose residual nitrates by bo:ling the residue with HC1l. Evaporate ’ghe golution to dryness and take up the residue in 5 ml of dilute HCl. Transfer the solution a little at a time to a plastic counting dish and evaporate to dryness under & heat-lamp. . PROCEDURE 4 Separation of beryllium from deep-sea sediments (II), Source. - P. S. Goel, D. P. Kharkar, D. Lal, N. Narsappaya; B. Peters, and V. Yatirajam, Deep-gea Research 4, 202 (1957). A simplified procedure for recovering Béio from samples of ocean- ' bottom sediments, assuming that the beryllium is adsdrbed on the surface of the clay particles. Procedure: - Step 1. ~Step 2. Step 3.. SteE 4 Step 5. Step 6. Add 5 mg of BeO to the dried sample and heat the sample to 500°C in a muffle furnace for 2 hours to destroy orga:uc matter Leach the_a igfii‘ted material 4 times with 190 mi of conc. HC1 and then wa.sh'the ins.oluble residue with 1:1 HC1 solution until the washirigsi are colorless. Combine the acid leach and washings and evaporate the solution to small volume. (N ote 1) Take up the residue in water and add 400 g of disodium EDTA. AdJust the pH of the solution to 4.5 - 5. ' _ Add 5 ml acetylacetone and shake for 5 minutes. Then extract the solution with four portions of benzene, shaking the mixture for 10 minutes each time. ‘Wash the combined benzene éxtracts with water at pH 5. Discard the washings and back extract beryllium with four portions of 6 N HCI. | ' | Transfer the solutlon a little at a time to a plastlc counting dish and evaporate to dryness u:;der a heat lamp. (Note 2) NOTES 1. The procedure as quoted in the original article states that an acetylacetone-benzene extraction is carried out directly on the HC1 solution after the .disodil.i_m EDTA has been added. Since the extraction with acetylacetone must be carried out from solutions of pH greater than 4,5, the éonsiderahie quantity of base which would be needed to bring the strongly acid solution to the proper 36 - PROCEDURE 4 (CONTINUED) pH would result in a very large volume of solution to be extracted. The details of the procedure from this point onward are not given in the original article. . Steps 3, 4 and 5 represent an attempt at giving epecific details of the procedure based upon information . given in the original article. 2.. It remains to be demonstrated to what extent this simplified procedure is capable of recovering Bd-:-10 from samples of sedimentary material. PROCEDURE 5 - Separation of beryllium from Clay by a solvent extraction procedure. Source - J. R. Merrill, M. Honda, and J. R. Arnold, (1o be published). . Procedure: Step 1. SteE 2. ‘Divide the clay sample into ca. 100 g units. Disperse each of them in a small amount of water in a 1 liter, heat- resistant polyethylene beaker. To the mixture slowly add 250 g of 48% HF followed by 80 ml of concentrated H,SO Add about 10 mg of beryllium carrier to the mixture. Tranefer the mixture to a 300 ml platinum dish and heat very 4 ' plowly over a small gas flame. Continue heating until the Step 3. Step 4. viscous solution which remains begins to solidify. Cool the mixture. | Heat the residue with 300 ml of water. Centrifuge any ‘undiesolved material, which should consist mainly of black organic matter and aluminum and calcium sulfates (Note 1). i much ma&acked _oi-iginal sample is present further bisulfate treatment is necessary. Combine the superpatant solutions from the several clay fi.n.it& {Note 2). To the combined solutions add EDTA in about 20% excess over the amount estimated for complexing the Fe and Al present. Add sufficient-water to bring the volume of the solution to about 3 liters. a7 Step 5. ~ Step 6. Step 7. SteE 8. Step 9. Step 10. PROCEDURE 5 (CONTINUED) Adjust the pH with ammonia to about 6,4 (Note 3).- When the solution becomes cool again add 25 ml of acetylacetone ‘and stir until it is dissolved. Transfer the solution to a large separatory funnel and extract the beryllium complex . with three 250 ml portions of benzene (Note 4). Combine the benzene sxtracts and wash them with 500 ml of water bufféered to pH 5-6 with dilute acetate. Discard the aqueous layer Back-extract bery]lium'from the benzene golution with two 4150 ml portlons of 6 M HCL. Combine the HC1 extiracts a.nd add 45 g of dlsodlum EDTA and enough ammonia to brmg the pH to 6 4. Allow the solution to cool, then add 40 mil of a.cetylacetone and stu‘ until it 13 dissolved Transfer the solution to a sepa.ratory fu.nnel a.nd extract with three 100 ml portions of benzene. Combine the benzene extracts, and after washing with 200 ml- of buffered water, back-extract beryllium with two 50 ml ‘portions of 6 N HCl. Combine the HCI1 extracts in a large beaker, add 10 ml of conc. Pm03_and heat the solution (caution!). Boil the solution nearly to dryness with - repeated additions of HNO 3 ‘Take up the residue from the evaporation in water and add ammonia to bring the pH to 8. Filter the precipitated Be(OH)Z- and ignite to BeO. . Weigh the BeO to determine chemical yleld and mount for counting (Note 5). | NOTES 1. Ina prel:.mmary experunent a Stockton shale sample was used as a:model and Be tracer was used to measure the recovery of bery]_lium. With about 10 mg of beryllium carrier it was found that the hot water .extracts of the sulfate cake contain almost all of the beryllium whereas 70-80% of total aluminum was left in solid form. 2. Sometimes the brown supernatant solution cbnta.ins some suspension (aluminum compound) <38 PROCEDURE 5 (CONTINUED) 3. The color of the iron - EDTA complex is useful as an indicator. 4. Occasional difficulties of separation -re'quire- centrifuging the organic layer at thie step. 5. The over-all yield of beryllium is about 60-70%. The procedure has been sufficient to remove all :adioiactive impurities from the clay samples which were analysed, but beryllium carrier is fiecessd’ry for good results. PROCEDURE 6 Separation of beryllium from clay by an ion exchange procedure, Source - J. R.. Merrill, M. Honda, and J. R, Arnold, (to be published). Procedure: Steps 1-3 Step 4. Sj:e.g 5. Step 8. - As in Procedure 5, using 20 mg of BeO carrier for a ' 200-300 g clay sample. Take 0.5 ml of the combined aqueous extracts of the sulf_fite cake and ana.‘l,ysé by EDTA complexiometric titration for Fe and Al (Note 1). | " | Addgraduallyamlxture of 2H 4 t 1Na »H Y-Z H O'+ 5 CaCO to the solution untfl about 0.1 mole of excess EDTA over that needed to complex Fe and Al, has been added. Adjust the pH to 3.5-4 with more CaCOB (usually about 100 g). (Note 2). Add 60 ml of glacial acetic acid as a bui'fer_(Note 3). Filter off the insoluble .CaSO 4" f.;'aCO3 and dilute the filtrate and washings to 10 liters. Pass the solution through ai li,ter" _D'owe:x 50 x 8 ion excha.ngé column in the sodifi:fi form. After this solution hae passed through, pass through 1 liter of 0.01 M EDTA + 0.1 M NaAc + 0.5 M HAc to remove any traces of Al and Mn ‘adsorbed on the column. {Note 4). Elute beryllium from the column with a solution of 0.5 M NaAc and 1 M HAc. About 0.5-1.5 column volumes of effluent contain all the berylllum. PROCEDURE 6 (CONTINUED) - Step 9. Precipitate Be(OH), from the effluent by the addition of ammonia. Filter the precipitate and ignite to BeO. Weigh to determine che_m.ical yield and mount for counting. ' NOTES For discussions of complexometric titration see G. Schwarzenbach, Analyst 80, 713 (1955); ''die Komplexometrische Titration", G. Schwarzenbach, F Enke, Stuttgart (1955); "Complexometric Titrations', G. Schwarz.enbach and H. Irvmg, Methuen and Co. Lid., London, Interscience Publishers, Inc., New York. (1957). Calcium carbonate is used to raise the pH 80 that the electiro- lyte concefitration will not be increased. Béry].liufn is not copercipitated with CaSO 4 | . If appreciable amounts of Mg or Ca are in solution they will replace Na+ from the ion exchange resin used in the succeeding step. In the presence of excess EDTA this increases the pH of ~ the solution, the most important variable in the process. To prevent . this enocugh HAc is added to the mixture to make the fina.l solution 0.1 M. . The completeness of removal can be checked by complexometric titration of the effluent. | PROCEDURE 7 Separation of berylllum from clay . Source - J. R. Arnold, Sc1ence 124 584 (1956). | Procedure: Step 1. . The sampl.e , consgisting of several hundred grams of wet clay, is treated with a mixture of 500 g of 48% HF and 500 g of 12 N HC1 in two 1 liter HH polythene beakers, after 10 ml of Be carrier (approximately 60 mg BeO equivalent) .- has been added. Evaporate to dryness in a hot-air jet. 40 Step 2. Step 3. Step 5. Step 6. 'SteB T. Step 8. Step 9. PROCEDURE 7 (CONTINUED) Add 150 g of each acld and again évaporate to dryness Evaporate to dry'ness twice more with a total of 500 g of HCI1 to remove most of the fluoride. Take up the sample in 1500 ml of 41 N HCI, boil, decant, and cent_rlfuge Heat the remaming golid with H SO until HF bubbles cease, Take up the cake with water and fuse any remaining solid with KHSO,. After dissolving the melt in water, discard any solid which remains and combine all solutions. - Add 650 g of tétrasodium EDTA and bring the solution to pH 6 to 6.5. Add 25 ml of acetylacetone, and after the solution has stood for 5 minutes_.exfract with three 250-ml - portions of reagent-grade benzene. Combine the benzene extracts and backwash them with acetate -buffered water at pH 5.5 to 6. ‘ Extract the benzene layer with two 150 ml portions of 6 N HCl-a.nd discard the orgehic phage. Add 45 g of disodium EDTA to the aqueous extracts and adjust the pH to 6 to 6.5. Add 10 ml of acetylacetone, and after the solution has stood extract it with three 75 ml portiens of benzene. Combine the benzene extracts, backwash them with acetate- | buffered water at pH 5.5 te 6, and then back-extract with two 50-ml porl:ion.e of 6 N HCi. Discard the or'ganic phase. Boil down the aqueous phase nearly to dryness with the addition of HNO to destroy organic matter, Take up in 50 ml of water a.nd preciplta.te Be(OH)Z with ammonia. Fflter the precipitate and ignite to BeO. Weigh the BeO to determine chemical recovery e.nd mount for counting. 41 PROCEDURE 8 Separation of beryllium from aluminum target material. Source - E. .Baker, G. Friedla.nder and J. Hudis, Phye Rev. 112, 1319 (1958). ' Bombarded aluminum targets contain Na.zz, which gives 0.51 Mev quanta that J'nterfere with the counting of the 0,48 Mev ¥ ray of Be. . Procedure: SteE 1. Step 2, SteE 3. ‘Dis_solve_ the aluminum in acid and add beryllium carrier. Prec'J'_.pitate beryllium and aluminum hydroxides with ammonia. Centrifuge and discard the aqueous phase. | Dissolve tlie mixed hydroxides in concentrated hydrochloric acid, add an equal volume of ether to the solution, cool in .. an ice bath, and saturate the solution with HCI gas. Step 4.. Step 5. . Step 6. SteE 8. Centrifuge and discard the precipitate of A_.Cl -6 H 50. Evaporate the 11quid phaee to small volume on a etea_m bath. Add dlstilled water and prec1p1tate Be(OH) w1th ammonia. C_ent_rlfuge and dl_s_card the aqueous phase. Dissolve the precipitate of Be(OH), in glacial acetic acid a_fid transfer the solution to a casserole. Evaporate to dryness on a steam bath. Repeet the evaporation to dryness with glac1a1 acetlc acid three more times. Take up the solld consisting of cryetals of baslc bery]lium - acetate, in (..'JHCI3 and transfer. the _CH_C13 sqlution to a separatory funnel. Wash the C_HC13 layer three times with ~an _equa.l volume of water. Discard the aqueous layer, Evaporate the CHCl layer to near d.ryneee Ta.ke up the resudue m a ema.ll amount of HINO Agam take the solution to drynese and them d:.lute with- water. Precipltate ZE’.e(OH)z 4OH Filter the Be(OH) prec1p1tate through a Whatman No. 42 filter paper. Transfer to a platinum crucible, char the paper, and ignite at 1000° for 4 hour. Grind the BeO to by addmg a slight exceas of I-]N 'a powder, glurry with 5 ml of ethanol and filter onto a- weighed filter paper disc. Dry in an oven and weigh to determine chemical yleld. Mount for counting. ‘42 PROCEDURE 9 Separation of beryllium from mixed figsion products and uranium, Source - J. D. Buchanan, J. Inorg. Nuc. Chem. 7, 140 (1958), Essentially the same procedure has been described by Baker, Friedlander, and Hudis, Phys. Rev. 112, 1349 (1958) for the separation of beryllium from cyclotron targets of copper, silver and gold. Two cycles of the procedure have resulted in a decontamination factor of 3 x 10° and a chemical yleld of 90%. Procedure; Step 1. Dissolve the sample in an appropriate acid and add beryllium (about 15 mg) to the sample contained in a centrifuge tube (50 ml). Stir well, then precipitate Be(OH)2 with a slight excess of NH 4OH. Centrifuge and discard the supernatant solution. Step 2. Dissolve the Be(OH)Z precipitate in 10 ml conc. HCl. Pass through a short column of Dowex 1X-10 resin which has been washed with conc. HC1 (Note 1). Wash the resin with 5 ml conc. HC1l. Collect the effluent in a centrifuge tube. Step 3. Reprecipitate Be(OH)Z with a slight excess of NH 4OH. Cen- trifuge and discard the supernatant solution. Wash the precipitate with 15 ml of water and discard the wash. Step 4. Dissolve the Be(OI-I)Z precipitate in min. of conc. HC1l. Add 3 mg Fe III carrier, dilute to 15 ml and heat on a water bath. Add 40 ml 8 N NaOH with stirring, and heat until Il?‘e(O]EI)3 coagulates. Centrifuge and decant the supernatant solution to a clean centrifuge tube, Step 5. Acidify the solution with HC1 and then precipitate Be(OH)Z with a slight excess of NH 4OH. Centrifuge and discard the supernatant solution, Step 6. Dissolve the precipitate in 3 ml glacial acetic acid and dilute the solution to 15 ml with water. Add 2 ml of 10% EDTA solution and then adjust the pH to 5 with NH 4C)H using indicator paper. Step 7. Add 2 ml of acetylacetone and stir the solution vigorously for a minute with a mechanical stirrer. Add 7 ml of benzene 43 Step 8. Step 9. . Step 10. Step 11. Step 12. Step 43. PROCEDURE 9 (CONTINUED) and extract berylliumm by stirring vigorously for a minute with the mechanical stirrer. Allow the two phases to sep- arate and transfer the benzene phase to a clean centrifuge tube by means of a transfer pipette. Check the pH of the aqueous phase and readjust to pH 5 if necessary. Repeat step 7 twice more, combining the benzene éxtracts with that from step 7. ' Back extract beryllium by adding 10 ml of 6 N HCI1 to the benzene solution and stirring vigorously for 4 min. Allow the phases to separate and transfer the HCl solutidn to a 150 ml beaker using a transfer pipette. Repeat step 9 once, combining the HCI extract with the first in the 150 ml beaker. Discard the benzene layer, | Evaporate the HCI solution just to drynese (do not bake). Add 5 ml of conc. H1§03 and evaporate just to dryness. (Note 2). ' Dissolve the residue from step 14 in 2 mi of conc. I-I.N'O3 and 10 ml of water. Add a slight excess of NH 4OH to precipitate Be(OH)Z. . Filter with suction on Whatman No. 42 paper. Transfer the paper and precipitate to a crucible and dry under ' a heat lamp or in a 100° oven. Ignite the precipitate to BeO at 1000°C for 1 hr or until precipitate is snow white. With the crucible inside a hood to avoid inhaling BeO dusit, grind the BeO to a powder with a stirring rod. Transfer the BeO to a tared filter paper by slurrying with alcohol. Wash with ethanol and dry at 90-400° for 10 min. Weigh the sample as quickly as possible as BeO 18 somewhat hj'gro- scopic. Mount BeO for counting. ' NOTES 1. The ion exchange column is made by sealing a tip 5 mm long by 2 mm diameter to the bottom of a 15 x 85 mm pyrex test tube, plugging the tip with glass wool, and filling the tube with resin to a height of about i inch. PROCEDURE 9 (CONTINUED) 2, If a higher degree of decontamination is needed, dissolve the residue in 10 ml conc. HCI1 and repeat the procedure from step 2. PROCEDURE 10 Separation of berylllum from cyclotron targets Source - J. B. Ball, G. H. Bouchard, Jr., A. W. Fairhall, and G. Mitra (unpublished). The following procedure is used where the target meterial is sandwiched between silver foils and bombarded with up to 44 Mev helium ions. Be7-which escapes from the target is caught in the silver foil. No Be7 is produced under these conditions in the silver foil iteelf. Because of activation of impurities in the silver foil several hold-back carriers are usgsed to improve the decontamination of the beryllium. The procedure is sufficiently general that a large number of target elements could be handled without much modification. The over-all chemical yield is in excess of 80%. | Procedure: Step 1. Diagolve the target and silver catcher foils in conc. HNO3. Evaporate most of the excess acid end add Be carrier (10 mg). Add hold-back carriers of Cu, Zn, Cd, In, Au, Hg and T1, where poseible as nitrates (Note 1). Step 2. Dflute the mixture to about 20 rfil with water and pass in ' HZS until the precipitated sulfides are well coagulated. Centrifuge the mixture and decant the supernatant solution 1o a clean centrifuge tube. Discard the precipitate. Step 3. Add conc. NH OH to the solution until the solution is faintly ammoniacal. Centrifuge the mixed precipitate of Be(O]E[)a and sulfides and discard the aqueous phase. Step 4. Add 6 N NaOH in sufficlent amount (about 1 ml) to dissolve the Be(OH) 2 from the precipitate. Dilute the mixture to about 20 ml with water. Centrifuge and discard any precipitate which may be present. 45 Step 5. Step 6. Step 7. Step 8. Step 9. PROCEDURE 10 (CONTINUED) To the supernatant solution add 3 to 4 drops of 10 mg/ml Fe III carrier, with swirling. Centrifuge and discard the precipitated Fe(OH)3. Add a drop or two of methyl red indicator and barely acidify the solution. Then add sufficient NH 4OH to turn the indicator yellow. Centrifuge the precipitate of Be(OH)Z. Dissolve the Be(OH)2 precipitate in a small amount of conc. HCl. Dilute the solution to 20 ml with water and add 2 ml of a saturated solution of the disodium salt of EDTA. Precipitate beryllium with NH 4OH. Centrifuge and discard the supernatant solution. Repeat the precipitation of Be(OH)z in the presence of EDTA twice more. Dissolve the Be{OH) 2 precipitate in a minimum of conec. HCl. Dilute to 20 ml with water, transfer the solution to a 50 ml plastic centrifuge tube and add 30 drops conc. HF. Heat the solution in a boiling water bath and slowly precipitate BaBeF, by dropwise addition of 5 ml of a saturated solution of Ba(NO Continue heating ), for 10 minutes and then centrifu;ezthe precipitate, Before discarding the supernatant solution check for completeness of precipitation by adding 1 drop more each of Ba solution and conc. HF. Take the precipitate up in a small amount of digtilled water and filter the suspension through a weighed RA -type millipore filter (Note 2). Wash with distilled water and dry in an oven. Weigh as BaBeF4. Mount for counting. NOTES 1. Gold carrier necessarily contains chloride ion which precipitates AgCl. A small amount of AgCl precipitate in the mixture makes no difference to the recovery of beryllium. 2. The precipitate is very fine-grained and next to imposasible to filter through ordinary filter paper. PROCEDURE 414 Radiochemical gseparation of beryllium Source - T. T. Shull, in "Cocllected Radiochemical Procedures', Los Alamos Scientific Laboratory Report Lia-41724, 2nd ed. {1958) 4. Imtroduction The determination of radicberyllium (BeT) is based upon the formation, after the appropriate decontamination steps, of basic beryllium scetate, Be 40 {OCOCH 3} 63 which is extractable by chloroform. The first decontamination step carried out on a solution of the sample is a ferric hydroxide precipitation by meang of an excess of sodium hydroxide solution. Beryllium, as a result of its amphoteric nature, remains in golution ag a beryllate, NaHBeOZ or NaZBeOZ‘ The beryllate is then converted fo beryllium ion and beryllium hydroxide precipitated with ammonia water. The hydroxide is purified by a series of acid gulfide precipitations in the presence of molybdenum, antimony, and tellurium carriers, respectively. Beryliium hydroxide is then changed to the basic acetate by acetic acid treatment. The basic acetate is extracied into chlorcoform, the chloroform is evaporated, and the basic acetate is dissolved in nitric acid solution. BRBeryllium is finally converted to the oxide, Be(Q, in which form it is weighed and counted. The procedure as outlined below requires approximately 18 hours and gives chemical yvields in the neighborhood of 35%. Although decontamination factors have not been determined, it appears that decontamination from gamms- emitting impurities is of a very high order. Z. Reagents Be carrier: 1.082 mg Be/mil {3.00 mg BeQ/ml)--(added as c.p. | BeSO, - 4H,0 in H,0) Fe carrier: 410 mg Fe/ml (added as FeCl3 s 6H20 in dilute HC1) Mo carrier: 40 mg Mo/ml {added as 1'\TI-I4)61\/&)7024 o 4:H20 in HZO} Sb carrier: .40 mg Sb/ml {added as SbC15 in 2M HCIL) Te carrier: 410 mg Te/ml (added as TeClAL in dilute HCI1) HCl: 6M HC1l: conc. HNOS: conc. 47 PROCEDURE 11 (CONTINUED) HC2H302: glacial NH 4OI-I: conc. NaOH: 20% by weight aqueous solution HZS: gas . Chloroform: anhydrous Ethanol: absolute. 3. Equipment Fisher burner Drying oven - Muffle furnace Centrifuge Block for holding centrifuge tubes Mounting plates Forceps Tongse for Erlenmeyer flasks 10-ml beakers (one per sample) 50-ml beakers (two per sample) Pipets: 1- and 10-mi 125-ml separatory funnels (two per sample) 125-ml Erlenmeyer flasks (one per sample) Ground-off Hirsch funnels: Coors 000A (one per sample) Filter chimneys (one per sample) Filter flasks (one per sample) No, 42 Whatman filter circles: 7/8" diameter--washed with ethanol, dried, and weighed _ No. 42 Whatman filter paper (9 cm) 2" 60° filter funnels (four per sample) 40-ml conical centrifuge tubes: Pyrex 8320 (14 per sample) Wash bottle ' Steam bath Hot plate .Stirring rods. 48 PROCEDURE 11 (CONTINUED) 4. Preparation of Standard Beryllium Carrier Dissolve 10. 62 gm of c.p. BeSO4- 4H20 -(Brush Beryllium Co.}, which has been dried overnight at 105°, in 500 ml of H,O. This gives a solution containing 1.082 mg Be /ml (equivalent to 3. 00 mg BeO/ml). Step 1. Step 2. Step 3. SteB 4, 3. Procedure Pipet exactly 10 ml of standard Be carrier.into a 40-ml conical centrifuge tube and add an aliquot of the sample and 1 ml of conc. HC1l. Heat to boiling and add 0.5 ml of Fe carrier. Bring the solution nearly to neutral by the dropwise addition of 20% NaOH. Transfer the solution to another 40-ml centrifuge tube which contains sufficient 20% NaOH to give the combined solution a 5% NaOH concentration. Stir vigorously during the transfer. Heat on a steam bath for 5 min, centrifuge, transfer the supernate to a clean centrifuge tube, and retain the Fe(OH)3 precipitate for Step 4. Add 0.5 ml of Fe carrier to the supernate with constant, vigorous stirring. Centrifuge, transfer the supernate to a clean centrifuge tube, and retain the Fe(O]E-I)3 precipitate for Step 4. Neutralize the supernate by the dropwise addition of conc. HCI. Make the solution ammoniacal with cone. NH 4O]E[. Heat for 5 min on a steam bath and then let the mixture stand for at least 10 min, proceeding in the meantime with Step 4. Combine the Fe(OH)3 preclpitates from Steps 41 and 2. Dissolve the combined precipitate in a minimum of conc. HCl1l. Transfer the solution into another centrifuge tube containing Buificienf 20% NaOH solution to givé to the combined solution a 5% NaOH concentration, Heat on a eteam bath for 5 min. Cenirifuge and transfer the supernate to a clean centrifuge tube, discarding the precipitate (Note 1). Neutralize the supernate with conc. HCIl and then make it ammoniacal with conc., NH40H. Heat on a steam bath for 10 min. 49 Step 5. Step 6. Step 7. Step 8. Step 9. SteB 10. PROCEDURE 11 (CONTINUED) Centrifuge the Be(OH)z precipitates formed in Steps 3 and 4. Combine both supernates in a 125-ml Erlenmeyer flask (Note 2}, Combine both precipitates by washing the smaller into the larger. Stir to break up the precipitate and then centrifuge. Transfer the wash liquor to the 125-ml flask above. Dissolve the Be(OH)Z precipitate in a slight excess of conc. HC1 and repeat Steps 1-5. Dissolve the Be(OH)z precipitate in a minimum of 6 M HCI, add ah additional milliliter of 6 M HCI1, and dilute to 10 ml with HZO' Add 0.5 ml of Mo carrier and bubble in HZS for 5 min. Centrifuge and decant the supernate into a clean centrifuge tube, discarding the precipitate. Heat the supernate for 10 min on a steam bath, pass in HZS for 2 to 3 min, and dilute to 20 ml with HZO' Centrifuge, transfer the supernate to the clean centrifuge tube and discard the precipitate. Heat the supernate to expel HZS' Add 0.5 ml of Sb carrier and saturate with HZS' Centrifuge and decant the supernate into a clean centrifuge tube, discarding the precipitate. Heat the supernate to expel HZS and add 0.5 ml of Te (IV) carrier. Boil and saturate with HZS’ centrifuge, and filter through a No. 42 Whatman filter paper using a 2", 60° funnel into another centrifuge tube (Note 3). Heat the filtrate to expel HZS and then make ammoniacal with conc., NH 4OH. Centrifuge and discard the supernate. Acidify the Be(OH)Z precipitate with 5 m} of glacial HC2H302 and evaporate the solution nearly to dryness, with constant gtirring over a low flame. Add 5 ml of glacial HCZH302 and evaporate to dryness over a flame, being careful not to let the temperature exceed 330°, the boiling point of basié beryllium acetate. Let the tube cool to room ternperature and extract the basic beryllium acetate with CHC13, using one 10- and three 5-ml portions of CHCl3 and centrifuging each time before decanting the supernate into a 125-ml separatory funnel. Retain the solid material in the céntrifuge tube. 60 Step 11. Step 12. Steg 13, Step 14, PROCEDURE 11 (CONTINUED) Wash the CHC1 3 extract four times with 4-m1 portions of I-IZO, transferring the wagh liquor to the centrifuge tube containing the material which was not extracted by CHCls. Filter the CHGI3 golution through dry No. 42 Whatman filter paper into a clean, dry 50-ml beaker, using a 2", 60° filter funnel. Evaporate the CHCl3 on a steam bath. While the CHCl3 is being evaporated, proceed with Step 11. Acidify the wash liquor and the CH_ClS-insoluble material from Step 10 with cone. HC1. Precipitate Be(OH)2 by the addition of conc. NH 4OI-I. Centrifuge. If an appreciable quantity of Be(OH)z is formed, convert it to the basic acetate as in Step 10 and repeat the CHC13 extraction, adding the bagic acetate extracted to that obtained in Step 10. Dissolve the basic acetate from the evaporated CHC1 3 extract by heating with a minimum of conc. HNO,. JIf 1t is felt that sufficient decontamination has been obtained, proceed immediately to Step 14. However, it is necessary ordinarily to proceed as in Step 13. , Transfer the solution to a clean centrifuge tube. Dilute the I-I'NO-3 solution to 15 ml with HZO and precipitate Bv.e(OH)2 by the addition of conc. NH 4OH. Centrifuge and discard the supernate. Repeat Steps 7-12, . Evaporate the I:INO3 golution to 1 to 2 ml and transfer to a 10-ml beaker. Carefully continue heating (on a hot plate) to dryness. Ignite for 1 hour at .250° in a muffle furnace. Cool, slurry the BeO with 3 to 5 ml of absolute ethanol, and pour onto a tared No. 42 Whatman filter circle in a filter chimney -ground-off Hirach funnel set up which contains 10 ml of absolute ethanol. Permit the solid to settle evenly on the filter circle (this requires about 10 min) before applying suction. Dry the precipitate by pulling air through the funnel for 2 to 5 min; then dry at 105° for 15 min. Cool and weigh. Mount and gamma ~count in gcintillation counter {Note 4). Be7 has only a 476-kev gamma ray. 51 PROCEDURE 11 (CONTINUED) NOTES An additional recovery of Be from the Fe(OH)'3 precipitated in Step 4 increases the chemical yield by about only 1 to 2%. The supernates from the Be(OH)2 precipitations in Steps 3 and 4 are saved as a precautionary measure. If much Be(OH)Z appears to have been lost at this stage, these supernates can be evaporated to a small volume and made ammoniacal for further recovery of Be. A small quantity of Be(OH) 2 is always formed by this treatment. Steps 8 and 9 probably could be combined with Step 7, i.e., all three carriers, Mo, Sb, and Te, could be added at the same time and precipitated as sulfides. Counting is begun immediately and is continued at intervals for a period of at-lea'.st 53 days (one half-life of Be7). It is well to check immediately for the presence of beta activity to determine whether any impurity which is both a beta and a gamma emitter is contaminating the Be7 and must be corrected far. Addendum to Beryllium Procedure If an appreciable amount of iron remains with the beryllium, i.e., enough to impart a yellow color to the Be(OH) 2 precipitate, just p.rior to the basic acetate step, it is advisable to make an ether extraction from 6 M HCI before proceeding. | The solids from the acetic acid evaporation are heated to a temperature of approximately 220° C to complete the formation of basic beryllium acetate. About 30% of the Be is converted to the basic acetate at 118 to 120°; however, 95 to 97% is converted at 220° C. Care must be exerdised to prevent the temperature from exceeding 330° and thus decomposing the basic acetate alfeady formed. The final heating is best accomplished in a constant temperature oil bath or under a heat lamp." ' The final, BeO, aftér ignition at 500° is transferred directly to an ‘aluminum éou.fiting plate rather than beifig slurried with alcohol and filtered. More reproducible results are obtained in this manner. 52 PROCEDURE 12 Separation of Beryllium from Fission Product Mixtures Source - G. M. Iddings, in "Radiochemical Procedures in Use at the University of California Radiation Laboratory (Livermore)', University of California Radiation Laboratory Report UCRL. -4377 (1954). Purification: From a 4-day old solution containing 1014 fissions and Yield: 9 7 about 10° beta counts per minute, a sample of Be was ' obtained which showed a beta activity of about 7 ¢ /m. About 70 per cent Separation time: About six hours exclusive of ignition. Step 1. Step 2. SteE 3. Step 4 SteE 5. Step 6. Step 7. | ‘To an acid solution of mixzed activities, add 410 mg Be carrier and about 5 mg of lanthanum carrier. Make the solution ammoniacal. Centrifuge and wash precipitate with dilute ammonia. Discard supernatant and wash. Add 10 ml 3 N NaOH to the precipitate. Digest for not more than five minutes in a not water bath. Centrifuge. Repeat leach with another 10 ml 3 N NaOH. Combine NaOH supernatants. Discard residual La(OH)3. Add ~ 5 mg Te+4 carrier to the NaOH solution. Add 5 drops of a saturated solution of NaZS. Add ~ 15 ml of a saturated solution of NH 4Cl. Centrifuge and wash Be(OH)z precipitate twice with water. Discard supernatants. Dissolve Be(OH)2 in 3 or 4 drops of c'bné. HCI, and add ~ 15'm] of a buffer solution of 0.5 N NaZSO3 and 1 N NaHSO3 (~pH 6). ' Transfer solution to a 60-m1, cylindrical, open-top, separatory funnel (with stem detached immediately below the stopcock). ' ' Add 30 ml of 0. 40 M TTA (thenoyltrifluoracetone) in benzene and equilibrate phases for ten minutes by rapid stirring with a motor-driven glass rod stirrer (paddle). b3 Step 8. Step 9. Step 10. Steg 11. Step 12. Step 13. Step 14. Step 15. Step 16. Step 17. Step 18. PROCEDURE 12 (CONTINUED) Wash organic phase twice with ~ 15 ml of water allowing three minutes for.each wash (to remove the sulfite). Wash organic phase twice with ~ 15 ml of 8 N ANO 3 for five minutes each wash (see Note 1). Wash organic phase six times with ~ 42 ml of a sclution whose composition is ~ 14 N HCl and 1 M H,SO, (11 ml conc. HCI with 0.7 ml conc. H,SO,) allowing ten minutes for each wash (see Note 2). Add ~ 415 ml of a solution consisting of two parts conc. formic acid and 4 part conc. HC1l. Agitate layers together for 15 minutes. Repeat and combine aqueocus layers. Make solution ammoniacal. Centrifuge the precipitate and wash with water. Add 10 ml of 3N NaOH and add Br, dropwise until solution becomes yellow., Stir. Add a saturated solution of N aZS dropwise until solution becomes colorless, then add 5 drops excess (to keep any Te in solution when the pH 18 lowered to 9 or 10 in the next step). Add 10 ml of a saturated solution of NH 4Cl. Centrifuge precipitate and wash with water. Acidify with HCI to pH 3-4 (by adding ~ 20 ml of 0.1 N HCI). Add ~ 5 mg Fe' 't carrier. Warm to ~ 60°C in water bath. Add 1.5 ml of 5% 8-quinolinol in 2 N HAc. Add 5-10 ml of 2 E" NH 4Ac to bring golution to ~ pH 5. Let stand for five minutes in 60°C bath, then cool to room temperature. Filter through No. 42 Whatman paper. Discard precipitate. (Separation of Be from Al, Pa, Zr, Nb and others.) Make filtrate basic with NH,OH. Filter through No. 42 Whatman paper. Wash with 1% solution qf NH 4Ac. Ignite to BeO for one hour at 1000°C. Transfer to tared aluminum hat and weigh rapidly (BeO is somewhat -h,ygroscopic.) Add a fe_w drops of Zapon (diluted fourfold with ethyl acetate). | 64 PROCEDURE 12 (CONTINUED) NOTES Té+4 is slowly reduced to Te metal by the sulfite, and it is carried along at the interface of the benzene-aqueous mixture. A 5-minute wash with 8 N HNO, will oxidize finely divided Te metal to Tet?, placing it in the acid layer. 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