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Determination of trace quantities of tin by neutron activation analysis
ANALYTICA
DETERMINATION
OF TRACE
CHIMICA
ACTA
QUANTI1’IES
VATION
OF TIN
335
BY
NEUTRON
ACTI-
ANALYSIS
Many conventional analytical methods have been proposed for the cletermination of traces of tin in a variety of samples. However, sufficiently sensitive methods for tin arc few. In addition, tlicre are serious rciLgcllt contamination problems for tile analytical methods. Special dctcrmination of traces of tin by the conventional attention has been paid to the radioactivation method in the Ii&l of trace ZMlillySiS during the past clccatlc, because of its great aclvanlxqyzs over otlier chemical or instrumental metliocls of analysis. As far as tlic rndioactivoti~)rl analysis of tin is concerned, several mctliods have been described for different materials, e.g. siliconl, germanium’, silicate”a3, beryllium*r, and iron and alloy steelsGe0. Thcsc mctllods, however, involve rather complicatccl radiochcmical procedures for tin, so that it is of interest to study more rapid and convcnicnt procedures having general applicability to a variety of samples. A method has also been explored for tlic activation analysis because of tin using x4-MeV fast ncutrons7; but it is only of limited applicability, of various competing nuclear reactions ant1 lack of sensitivity. In the present work, a rapicl proccclure was developed for the activation analysis of tin, down to the 0.1 pg level, in silicate rocks, sea waters, biological materials, and several kinds of iron alloys. There are no data available in the literature about the activation analysis of tin in biological materials and in sea water. We were also particularly interested in trace analysis of tin in silicate rocks, because there is still considerabledoubt aboutthe abundanccof tin insilicatematcrials of gcochemical interest H.U.In internationalcollaborative tests involving various analytical techniques for two standard rocks, the agreement in values for tin has not been very satisfactory, which implies that cvaluntiori of conventional trace methods for tin is rccluircd 10. Matrix effects in spectrochemistry, and contamination from reagents or incomplete decomposition of tin-bearing minerals in wet methods, are likely to affect the trace determination of tin.
The nuclear characteristics of tin rclcvant _.__... -..- .- ---. lkcult~ + Prcscnt atlclrc~s: Chcrnistry Laboratory, (Japan).
to activation of Eclucntion,
with tlicrmal l’:himc
University,
neutrons are Matsugamrr
H.
336
._.._.__.-
_.-._
HAMAGUCHI,
_-..-_.-----.. /~~Jlt,ldU,ZC,Y
IsVhpc
( ‘%J
’ “%I1
I .I .2 ‘I
1 I’Sn
7.57 2‘1.01
1 l”Sr1
.
I<. KAWARUCHI,
-. . .._..___-
.
N. ONUMA,
.
.
. -_---..
1~. KURODA
.
tfdf-lift of uclivuI iow prodllCf
Cross-scctio,r (hums)
-
-
.___
. . . .._-...__._--.......
Principd radi%ion
Principd Y ratlidion
8.9 31.97
lni!qn
4.71 5.9
_._.__..__._..._ ___.-____ .^_. .-.-_----_. ”
s =
1~M
=
.._.. . . ..-_- __._ __-._
_
____._.._
.
Htablc
nlulliplc
Karnrnan
listed in Table I. Tin-Izo is convenient as a target nuclidc for activation analysis, because of its grcatcr abundance, rclativcly high cross-section and the suitability of the half-life, radiation and energy of the activation product. Irrndintio?c
md
activity
mwswenwnt
solid sample was weighccl and sealed in a polyethylene tube. Tin in sea-water samples was collcctcd into 30 mg of iron hyclroxiclc through coprccipitation from IO 1 was then processed in the same of sea-water samples. The air-dried iron hydroxide way as solid samples. An aliqnot of standard tin SOlUhn (414 pg sn) was impregnated into a piccc of filter pnpcr plncccl in a polycthylcnc tube and sculcd. Samples and standard were tllcn positioned inside a polycthylcne capsule with aluminum packing foil and irracliatccl for 3 days (intermittently 5 11 a clay) at a power level of 50 kW and a neutron flux of about 3 1011 n/cm2/8ec, using the water-boiler type Japan Research Reactor JRR-I. After cooling for a day, the irradiated samples ‘were processed chemically to obtain racliochcmically pure tin(IV) oxide for /&counting. @Counting was performccl using a stnnclarcl-type mcthanc-flow proportional counter. Appropriate decay, gcomctry and self-absorption corrections were applied. The
l
Sensitivity If ;L counting cfficicncy of 35%, ancl an effective lower limit of detection of I0 counts/min are assumed for the proportional counter. and if the time required for cooling and chemical separation (totalling 45 Ii) arc taken into account, as well as the 50% chemical yield, then the clctcction sensitivity attainable can be estimated to be 2 . IO-’ g. This sensitivity should be good enough for most determinations of tin in a variety of samples. Amal.
Chinr.
clcla,
30 (I&+)
335-345
DETERMINATION
OF TRACES
OF
Sn
337
Reagents Standard tin sol&on. Dissolve 0.0528 g of pure tin metal in 5 ml of I : I nitric acid along with 3 g of tartaric acid and dilute to 25 ml with water. Standardize gravimetritally by taking an aliquot of the solution. Carrier sohtim. Tin. IO mg Sn/ml. Dissolve x.01 g of tin(I1) chloride in 17 ml of hydrochloric acid, and dilute to xoo ml with water. Standardize the solutiongravimetrically. Holdback cavriersohtion. Antimoq. 0.5 mg Sb/ml. Dissolve 0.05 g of pure antimony metal in 13 ml of sulfuric acid. Boil the solution with 0.2 Q of hydrazine sulfate, cool and dilute to IOO ml with water. Arse?ric. 2 mg As/ml. Dissolve 0.27 6 of arsenic trioxide in 4 ml of I N sodium hydroxide, dilute with water, acidify slightly with hydrochloric acid and dilute to I00 ml with water. Copper. 2 mg Cu/ml. Dissolve 0.78 6 ot copper sulfate in 100 ml of water. Iro?t. 2 mg Fe/ml. Dissolve x.0 g of iron(III) chloride in xoo ml of I N hydrochloric acid. Dissolve I 6 of the reagent in Diet~tylatrr?nolri.trnr dietkylditlliocarbavtnte soltrtiou. IOO ml of chloroform. Prepare just before use. Iso)robylacetom. (CH&CHCH&OCHa. Analytical grade. All the chemicals used wcrc of analytical-grade quality.
Decomjosition An outline Silicate
of irradiated
of the radiochcmical
samples
separation
and
firelinrinary
separation
of
tin
scheme is shown in Fig. I.
rocks
Silicate rocks arc obtained in solution either by digestion with sulfuric-hydrofluoric acid or by fusion with sodium peroxide. For the cligestion, transfer an irracliatcd silicate rock sample quantitatively to a so-ml platinum dish. Add 2 ml of tin carrier solution, 5 ml of 18 N sulfuric acid, I ml of nitric acid and IO ml of hydrofluoric acid. Evaporate to strong fumes of sulfur trioxidc, occasionally adding a few ml of Take up the residue in x.00 ml of hydrofluoric acid to complete the decomposition. water and 20 ml of 25% tartaric acid solution. Pass hydrogen sulfide through tllc solution to precipitate tin(W) sulfide. Proceed as described under RadiockcnticaZ sej5avation of ti7c below. For the fusion with sodium peroxide, add 2 ml of tin carrier solution to a so-ml nickel crucible, then add dilute ammonium hydroxide to precipitate tin(IV) hydroxide and evaporate to dryness. Put the irradiated silicate rock sample into the crucible and fuse for 5 to IO min with G g of sodium peroxide. Dissolve the melt in 20 ml of hydrochloric acid and dilute to 200 ml with water. Add 20 ml of 25% tartaric acid and pass hydrogen sulfide to precipitate tin(IV) sulfide. Continue as described under Radiochemical sefiaratiott of tin. Sea
water
To recover tin in sea-water samples, add 30 mg of iron(II1) to a 2-l portion of sea water containing 40 ml of hydrochloric acicl, heat and precipitate iron hydroxide by R7ral.
Chim.
Ada,
30 (19G4)
335-345
‘al
L
Y Ir,
u
w
;_
I
HIS.
Add Sna+ carrier. Fuse with Sa202. Dissolve in HCI. Dilute, add CIHeOs and pass
I-.-_-.-
Add SnJ; carrier. Decompose with H9,S04-HSOa-HF and evap. to fumes. Take up in H&, add &He06 and pass HZ’%
---
Silicate
SH:OH.
_-!-SnS2 ’ _.-.--._
HaBOakd pass HG.
I ; Aqueous
with isopropylacetone.
and add Feay carrier.
.-_ _.. .._..
..^ -..-
of
Fig. I. Chemical separation
Ignite add weigh.
hl%,!j
scheme for tin.
Dissolve in HXO~-HC~OJ and crap. to fumes. -- I
Add HaBOa and pass H&L I SnSl I .-
Back-extract Ato 2-5 _Y HF. I ._ -..--. Aqueous,
Dissolve in hot Hk0~: SeHaSOd. _-kid SbJ’, ;\sa~ and Cu”+ carriers. Diluteandestract with CHCl& (C?Hs)~SCSSSH~(C~Hj)~. _._-L_-\qucous I Add KI and estract with isopropylacetone. ._._I ---Organic !
Add
Estract
sps,
.F--!--
Dissolve in HCl-HF
__.’
Irradiate for 3 days. Dissolve in HCI. Add Sna+ carrier and C4H&. Pass H&k /
Fc(OH)s -/--
Dissolve in HCl and transfer to another 2-l portion sample. Repeat precipitation _I times. I
Fe(OH)ai -___
Sea water ------Add HCI, 30 rng 1% and then __- I -
I’usc with Sa:Oz. Dissolve in HCl, dilute, add C4H&~. and pass H&.
Add SnJ+ &ier. Decompose with HS03+ H&04. Add HClO( and cvap. to fumes. ---- I SnOz
-. _...--Biolo4cal material : _ .__” Add SnJ- carrier. Dissolve in HCIH2S04-HSO~. Dilute, add C4H60e and pass H$.
Jkroalloys -i -. -.-
..___.
!
DETBRMINATIOh’
OF TRACES
OF
sll
339
dropwise addition of x : I ammonia solution. Dissolve the precipitate in 40 ml of hyclrochloric acid and transfer to another z-1 portion of water sample. Precipitate iron hydroxide in the same way. Repeat the precipitation 5 times to recover tin from 10 1 of the sample water. Wash the final precipitate thoroughly with 2% ammonium nitrate solution, dry and irradiate as mentioned above. Dissolve the irradiated iron hydroxide in zo ml of G N hydrochloric acid containing 2 ml of tin carrier solution. Adjust the acidity to about I h! in hyclrochloric acid ancl precipitate tin(IV) sulfide as described above.
Decompose the irracliatcd biological sample with 3 ml of sulfuric acid and q-ml portions of nitric acid in the presence of 2 ml of tin carrier solution. When the dccomposition is complete, adcl 3 ml of perchloric acid and heat until white strong fumes begin to appear. Dilute and filter the precipitated tin(IV) oxide through a filter paper. Fuse the tin(IV) oxide with 5 g of sodium peroxide, fnllowing the procedure described for silicate rocks.
Transfer an irradiated sample of fcrroulloy to a so-ml beaker containing 2 ml of tin carrier solution, 20 ml of 6 N hydrochloric acid. 4 ml of 18 N sulfuric acid and 2 ml of nitric acid. Heat gently OXIa hot plate until the sample has dissolved. Filter off the residue consisting of graphite and dilute the filtrate to 150 ml with water. Add I to 2 g of tirrtatk wit1 zinc1 precipitate tin(IV) sulfitlc iIS before.
Dissolve the tin(IV) sulfitlc in 5 ml of hydrochloric acid. Add 2 mg of iron(lI1) carrier, 5 ml of 2.5 N hydrofluoric acid and 5 ml of water ancl shake for 30 see with 15 ml of iSol’rO~)yli~cctOlle. Drain the ilClLlC!CJUS pIliWe (lower) into a So-nil centrifuge tube containing IO ml of saturated boric acid solution. Pass hydrogen sulfide to prccipitntc tin(IV) sulfide. Centrifuge and discard the supernate. Dissolve the precipitate in 4 ml of sulfuric ncid in the presence of 0.2 g of hydrazinc sulfate, and 2 mg each of Sl++, A++ and Cu2+ carriers. Add 22 ml of water and extract foreign activities by shaking with zo-ml portions of dicthylammonium dicthyldithiocarbamate solution in chloroform until the color of the extract disappears. Add 5 Q of potassium iodide to the aqueous phase and extract tin(IV) iodide by shaking for 30 see with 20 ml of isopropylacetone. Wash the organic phase twice with ro-ml portions of 1.5 N potassium iodide in 3 N sulfuric acid. Strip tin(IV) iodide by shaking with IO ml of 2.5 N hydrofluoric acid; 20 set is enough for stripping. Add 15 ml of saturated boric acid solution to the aqueous phase ant1 pass hyclrogcn sulfide to precipitate tin(IV) sulfide. Dissolve the precipitate in a mixture of I ml of nitric acid and 2 ml of pcrchloric acid and cvaporatc to strong fumes. Dilute with water, filter the precipitate through a filter paper, dry and ash. Slurry the tin(IV) oxide with a few ml of water, transfer to a weighed small filter paper, and wash with water and then with acetone. Dry at 1x0” for 10 min, cool and weigh to determine the chemical yield. Mount for the activity measurement. Treat the comparative staxzclarcl in a similar way. .I ml. Chim. ncrn, 30 (1061) 335-345
340
H. HAMAGUCHI,
K. KAWABUCHI, RESULTS
AND
N. OSUMA,
R. KURODA
L)ISCUSSION
Separation of tin from arsenic, antimony, molybdenum and tellurium presents the most difficulties in thcradiochemistry of tin ll.The isopropylacetonehydrochloric acid extraction system has been found effective for tin(W) but it is not spccificl2. However, most of the intcrfcring elements in this system can be removed by extraction with a solution of diethylammonium diethyldithiocarbamate in chloroform from sulfuric acid medium; this leaves only tin(IV), antimony(V) and arsenic(V) in the aclucous phase l 3*14. Extraction of antimony and arsenic can be achicvcd by reducing to the lower oxidation (trivalent) state with, for example, hydrazine sulfate in sulfuric acid solution f.6, which leaves tin( IV) unchanged. In order to shorten the chemical separation, an attempt was made to extract foreign activities by isopropylacetone from a solution which was 6 N in hydrochloric acid and 0.8 N in hydrofluoric acid, the tin remaining in the aqueous phase. This extraction can be omitted in the radiochemical separation involving silicate rocks, materials, because the carbamate extraction sea-water samples and biological followed by the iodide extraction- stripping system provides a satisfactory separation irom molybdenum as well as from most other contaminants, including antimony and arsenic. However, the first isopropylacctonc extraction is an essential step for ferroallays, particularly if they contain appreciable amounts of molybdenum as an alloy constituent. For high-molybdenum alloys like SCS 14 steel in Table II, additional puri-
Ttme (days)
Fig. z. Ikcsry curve of inducctl 121% activity isoldccl from an irmtliatcd steel. (Ia) Gross tlccay of compnrativc stnntlnrcl: (Ib) lzlSn tlt!Cily obtninctl by subtraction of long-livccl frnction in compnrntivc standard: (IIn) gross tlccay of tin nctivitics isolatccl from the snmplc; (IIb) 121% decay oldaincd by suhtrrrction of long-lived activities in the sample. .*Irlcrl. Chiw.
rl c/n. 30 (rgG4)
335-345
DETERMISATION
341
OF TRACES OF %I
fication is necessary in order to obtain radiochemically pure tin(IV) oxide. For this purpose a single scavenge with molybdenum sulfide or a-benzoinoxime is effective. In Fig. z a typical decay curve is illustrated for induced tin activities obt’&.i%d from an irradiated ferroalloy sample. Analytical results for several kinds of ferroalloys are given in Table II along with the main constituents other than iron. In the same Table are listed results which have been obtained by the present authors using an activation method of analysis accompanied by chemical separation as reported by LEADER*~ (abb reviated to “precipitation procedure”).
0.45
3.23 0.50 0.32 0. I .j
0.M
12.17 ‘7.78 2.31
(J.5178
168~
o..?r3q
I f>S”
0.2513
101
0.3Mib
IIC>b
l
0.3030
53.5’
0.2007
s7..5h
There remain problems in the conventional analyticCal procedures for traces of tin in silicate rocks. Values for tin in the two internat,ional rock standards C-I and W-I provide the evidence for this point (Table III). It can bc seen that the agreement in values for tin is not very satisfactory between analysts. Further evidence may be found by literature surveys on the abundance of tin in materials of geochemical interest, in which markedly controversial results have been reported. For example, GOLDSCHMIDT AND I%*reI@S gave a spectrographic value of 40 p.p.m. Sn for a composite of 36 European Paleozoic sh‘ales, whilst ONISHI AND SANDELL~~ found calorimetrically the much lower value of 5 p.p.m. Sn on the same sample. A matrix effect in spectrochemistry or incomplete decomposition of silicate materials (or a reagent blank) in wet methods could be responsible for such controversial results. Activation analysis with a radiochemical procedure involves the assumption that the radioisotopes induced arc in an identical chemical form with the carrier which is to be added. In the development of the radiochemical procedure, we first tried to find a proper method of attack for silicate materials, because certain tin-bearing minerals Anal.
Clritn. Acla,
30 (19G4) 335-345
342
H. IiAhIAGUCHI,
K.
KAWARUCHI,
‘l’A131.15 VALUILS
-_
TIN
ONUMA,
It. KURODA
III
IN G-r
ASI)
IV-1
_.
G-r (p.p*Itl.) --_.-- -._...-...--’
r;OK
N.
‘2
IV- I (P.P.,rr. J
______.__ < ‘2
5
_--
2.3 (av.) 5. I (av.) 8.8 (nv.)
2.8 _--
C.5 .< 210 3.3 (at,.) 3.4 (xv.)
. . _._.._..._. _______ ___ _.. _. _.
(av.)
x.7
(xv.)
2.5
(ilv.)
‘:s <.,zo 3**1 (av.)
_____- ._._
.._._
. .._...--- ^____ -___-
__..__
Sl~cCtr~~ClIcIlliCilI
Sl’cctroclicriiir;il Clwmical Spcctroclicrnic;ll Sl’cctrocllclllic;iI Spcctrocl~crnical Spcctroclicmical C:hctnical Activ:rtion
like citssiterite in silicate rocks arc strongly resistant to hytlrofluc~ric acicl. In 'I'ablcIV tllc results obtninccl by digestion with hydrofluoric acid anal by sodium pcroxidc fAon ;trc given for G-r granite; tllcre is no significilnt diffcrcncc in results between the two proccdurcs. The s;imc is true for determinations of tin in a biotitc granite (‘l’ablc IV). So far as the usual types of igneous rocks arc concerned hot11 opening-up 1)roccdurcs seem to be satisf;M.ory. In order to dctcrminc tin in se;\ water it is not ackcluate to irradiate? scn. water itself, lxcause of tlw high activities induced by irradiation and of the small snmplc sixc which is limited by the irracliation.space. Accordingly, tin was concentrated from 10 1 of sea water by coprecipitation with iron(II1) llyclroxidc. In orclcr to cllcck the rccovcry of tin, a tin-rzr tracer was added to 2 1 of sea water along with il pg amount of inactive tin carrier (tin(IV) chloride form). Iron(II1) hyclroxicle was then prccipitatecl by tlropwisc addition of ammonium hyclroxide. liccovcry of tin was satisfnctory (Table V), proviclecl that sufficient iron(II1) was added as tlic collector. The overall yield for the collection of tin from I0 1 of sea water, in which tlic precipitation of iron(II1) hydroxide from 2-l portions of SC;1 wntcr was rcpcatccl 5 times, ilVt2IYlgC!Cl C)87/,; this figure was applied as a cor. rcction factor for the practical clctcrmination of tin in sea waters. Values for tin in scvcra.1 sea-water samples are Given in Table VI. The total rcagcnt blank from the iron collector (30 mg Fc:~+, ammonium hyclrosiclc and hydrochloric acid which are usccl to collect tin from IO 1 of water sample) was chcckccl each time; the figures are also given in ‘l’ablc VI. The use of cloublc amounts of hydrochloric acicl (runs I and 2) increased blank values by a factor of two. ‘I’hc blanks arc I~robnbly contributed mainly from hydrochloric ncitl or ammonium liydroxicle. Tlic results of determinations of tin in marine organisms arc summarized in Table VII. .*I ~~41. Chiw.
.4ckz,
30 (I@.+)
335-345
DETEI~NIMATION
OF TRACES
OP
sll
343
The proposed radiochemical procedure is reasonably rapid and gives a high degree of radiochcmical purity with rather uniform chemical yields running to about 50%. In most cases it takes less than 3 11 to complete the whole l>roceclure, because tedious precipitation steps have been replaced as far as possible by rapid and effective solvent extraction methods.
Correction for self-absorl)tion and back-scattering in sources for measuring flactivity is necessary because of the rather weak maximum p- cncrgy, 0.38 McV, of ‘“‘Sn. ‘Tlic correction curve indicates that the combined effect of self-absorption and scattering increases with increasing tllickncss of the tin(IV) oxide sources. In actual the correction was not always carried out because of the uniform practice, howcvcr, chemical yields obtained throughout tile work. Attention must also bc paid to the self-shielding effect of the sample against neutrons during irradiation, leading to a reduction of the cffectivc neutron flux through a sample and causing uncclual acti-
344
H. HAMAGUCHI,
K. KAWABUCHI,
X. ONUMA,
R. KURODA
vation of the sample. For practical purposes, weights up to 1.3 g of the usual types of silicate rocks and r.G g of iron meteorites can be tolerated for irradiationz0s27. To investigate this effect in comparative standards, varying amounts of tin (as nitrate) were irradiated and the induced specific activities were cletcrminecl. No significant cllangc in the specific activity was detcctablc over the testecl range of 104 to 620 pg Sn. ‘The possible competing nuclear reactions, 12fSb (n, p) 12lSn and 124Tc (n. dc) 1“‘Sn, seem unlikely to contribute to the final result unless these reactions have exceptionally high cross-sections. In addition, the elemental abundances of antimony and tellurium arc so low that interference at any significant level is unlikely to be serious. For samples containing an appreciable amount of uranium, the production of 121% through a fission reaction 23fiU (n, f) 12lSn must bc taken into consideration. Although the &ion yield for this reaction is only o.o14~~, I pg of natural uranium gives a lz*Sn activity corresponding to approximately 0.01 /~g Sn under the irradiation conditions stated above. In almost all cases the contribution of l2lSn from uranium fission is unlikely to bccomc serious so far as samples containing little uranium arc concerned. SUMMAI
1Jnc mL(thodc par activnlion au moycn dc neutrons cst appliqudc nu dosngc dc traces d’dtain dans tlivcrs L’chnntillons (Riliciltc%, ciwx dc mcr, substances biologiqucs ct acicrs). <‘c?ttc mdthodu cst rapidc ct pcrmct dc doscr jusqu’tr 0.1 pg d’btain, cn compnrent I’nctivitr! p induitc dc Ia*% (27.5 II) uvcc ccllc d’un dtnlon.
Es wurclc cinc allgcmcin unwcndbarc Mcthodc zur Ikzstimmung von Spurcn Zinn mit Ililfc dcr Ncutroncnaktivicrungsnnnlysc cntwicltclt. Die l’rolwn und VcrgIcichsstandartlR wurdcn insgcsamt 3 ‘I’agc lang bci cincm Ncutrorwnfluss von cu. 3 * 1011 n/cm3/scc bcstrahlt. Es folgtc cinc radiochcmischc Trcnnung mit Tr!igcr vorwicgcnd tlurch Fllissigcxtmktion. Noch o. I pg %inn kann lcicht durch Vcrglcich dcr P-hktivititt dcs la*Sn (27.5 h) mit dcr cincv Standards bcstimmt wcrdcn. IXc Mcthodc iut schncll und hat cinc chcmisclrc Ausbcutc von ctwn 5o’X. Es wcrdcn die Zinngchrrltc von cincr 1Ccihc Mutcrirrlicn wit Silikatgcstcin, Sccwasscr, biolo&schcs Material und Stahl sngcgcbcn.
1 J. 1’. GALI, in R. C.. tiocrr, /tc(ivrcliotl .4rwlysis MnndOoolr, Aciltlcmic Prcns, New York, 19’51, p. 17.2. 1 I-I. MAMAGUCHI, 17. KUROIM, 'T.SHIZIIIZU. I<.SUGISITA, 1.TSUICAHAHA AND R. YABIAMOTO, J. n 1. Emvgy sot. Japrln, 3 (19Gr) 800. 3 EI. ~~AMAGUCHI, I<. I
AND V. N. ZAMYA'TNINA, %/I. .I~nlit. f
London,
1954.
n nrcl. Clritr1. ncm, 30 (rgG4) 335-345
IXTERMINATIOX
OF TRACES OF Sn
1” M. FLI~XX~H AND R. E. STEVENS, Geochim. Cosnwchitn. Ada, 11 W. E. NEHWK, The Radioclremislry of Tilt, NAS-NS, No. 3023, 12 H. GOTO, Y. ICAKITA AND T. FURUXAWA, J. Cicem. Sot. Japan.
345
zc) (rgGa)
525.
1960.
79 (1958) 15x3. 13 P. P. WYATT, A,~ulysf, 80 (1955) 3G8. lj c. L. IdUKE, A7lUl. Che?PJ., 28 (1956) 1276. 1.5 W. F. HXLLEURAND, Applied I?torgatric Analysis, 2nd Ed., \Vilcy. New York, 1955, p 70. Itadiochemical Studies. The Fission 10 G. R. IAADI:R, in C. I>. COHYBLL AND N. SUGARMAN, Producfs, 13ook 2, Part V, McGraw-Hill, New York, 1951, p. 919. 1’ K. K. TUREKIAN, Science, XZG (1~57) 7.)5. 18 A. A. Cno~os. quoted in ref. g. 19 H. ONISHI AND 13. B. SANDELL, Geochim. Cosmachim. Acfn, I 2 (1957) 262. 10 N. HKRZ ANU C. V. DUTRA, Geochim. Cosnrochinz. Acla, 2 I (rgcjo) 81. AHICENS AND S. R. TAYLOR, GeociJinr. Cosntoclrirn. Ada, 18 (1960) 162. 21 R. R. IhOOKS, I,.1-I. 12 TH. I-iUcI, quoted in ref. IO, ss written communiczLtion. Cosmorhim. .4c/u, 20 (IgGz) 51 I. 23 M. C. CLAKK ASI) D. J. SWAINIS, Gcochim. zJ I. ~AKhlIcIIAISL AND 11. ,\rCI>ONALIJ. C’COCkit?Z. COSmUChi,,,. .4hZ, 22 (lgf>l)87. Ia \'. 31. (;OI.DSC~ISIIDT AND C. I’ETISRS, Nuclir. (;es. Lviss. Giilfi*JgeBJ, iTlath.-physih. kehSSC 111: 30; I I’: 37, 278 (1933). 23 H. HAMAGUCI-II, G. M’. REED AND A. TUHKKVICI;, Geoclritn. Cosrt~oclrint. Ada, 1;1 (1957) 337. D? I-1. I-iAnlAGUcHI, 1‘. NAKAI AND Y. l
.4 eta,
30 (ItJc,q) 335-345
DETERMINATION
OF TRACE
CHIMICA
ACTA
QUANTI1’IES
VATION
OF TIN
335
BY
NEUTRON
ACTI-
ANALYSIS
Many conventional analytical methods have been proposed for the cletermination of traces of tin in a variety of samples. However, sufficiently sensitive methods for tin arc few. In addition, tlicre are serious rciLgcllt contamination problems for tile analytical methods. Special dctcrmination of traces of tin by the conventional attention has been paid to the radioactivation method in the Ii&l of trace ZMlillySiS during the past clccatlc, because of its great aclvanlxqyzs over otlier chemical or instrumental metliocls of analysis. As far as tlic rndioactivoti~)rl analysis of tin is concerned, several mctliods have been described for different materials, e.g. siliconl, germanium’, silicate”a3, beryllium*r, and iron and alloy steelsGe0. Thcsc mctllods, however, involve rather complicatccl radiochcmical procedures for tin, so that it is of interest to study more rapid and convcnicnt procedures having general applicability to a variety of samples. A method has also been explored for tlic activation analysis because of tin using x4-MeV fast ncutrons7; but it is only of limited applicability, of various competing nuclear reactions ant1 lack of sensitivity. In the present work, a rapicl proccclure was developed for the activation analysis of tin, down to the 0.1 pg level, in silicate rocks, sea waters, biological materials, and several kinds of iron alloys. There are no data available in the literature about the activation analysis of tin in biological materials and in sea water. We were also particularly interested in trace analysis of tin in silicate rocks, because there is still considerabledoubt aboutthe abundanccof tin insilicatematcrials of gcochemical interest H.U.In internationalcollaborative tests involving various analytical techniques for two standard rocks, the agreement in values for tin has not been very satisfactory, which implies that cvaluntiori of conventional trace methods for tin is rccluircd 10. Matrix effects in spectrochemistry, and contamination from reagents or incomplete decomposition of tin-bearing minerals in wet methods, are likely to affect the trace determination of tin.
The nuclear characteristics of tin rclcvant _.__... -..- .- ---. lkcult~ + Prcscnt atlclrc~s: Chcrnistry Laboratory, (Japan).
to activation of Eclucntion,
with tlicrmal l’:himc
University,
neutrons are Matsugamrr
H.
336
._.._.__.-
_.-._
HAMAGUCHI,
_-..-_.-----.. /~~Jlt,ldU,ZC,Y
IsVhpc
( ‘%J
’ “%I1
I .I .2 ‘I
1 I’Sn
7.57 2‘1.01
1 l”Sr1
.
I<. KAWARUCHI,
-. . .._..___-
.
N. ONUMA,
.
.
. -_---..
1~. KURODA
.
tfdf-lift of uclivuI iow prodllCf
Cross-scctio,r (hums)
-
-
.___
. . . .._-...__._--.......
Principd radi%ion
Principd Y ratlidion
8.9 31.97
lni!qn
4.71 5.9
_._.__..__._..._ ___.-____ .^_. .-.-_----_. ”
s =
1~M
=
.._.. . . ..-_- __._ __-._
_
____._.._
.
Htablc
nlulliplc
Karnrnan
listed in Table I. Tin-Izo is convenient as a target nuclidc for activation analysis, because of its grcatcr abundance, rclativcly high cross-section and the suitability of the half-life, radiation and energy of the activation product. Irrndintio?c
md
activity
mwswenwnt
solid sample was weighccl and sealed in a polyethylene tube. Tin in sea-water samples was collcctcd into 30 mg of iron hyclroxiclc through coprccipitation from IO 1 was then processed in the same of sea-water samples. The air-dried iron hydroxide way as solid samples. An aliqnot of standard tin SOlUhn (414 pg sn) was impregnated into a piccc of filter pnpcr plncccl in a polycthylcnc tube and sculcd. Samples and standard were tllcn positioned inside a polycthylcne capsule with aluminum packing foil and irracliatccl for 3 days (intermittently 5 11 a clay) at a power level of 50 kW and a neutron flux of about 3 1011 n/cm2/8ec, using the water-boiler type Japan Research Reactor JRR-I. After cooling for a day, the irradiated samples ‘were processed chemically to obtain racliochcmically pure tin(IV) oxide for /&counting. @Counting was performccl using a stnnclarcl-type mcthanc-flow proportional counter. Appropriate decay, gcomctry and self-absorption corrections were applied. The
l
Sensitivity If ;L counting cfficicncy of 35%, ancl an effective lower limit of detection of I0 counts/min are assumed for the proportional counter. and if the time required for cooling and chemical separation (totalling 45 Ii) arc taken into account, as well as the 50% chemical yield, then the clctcction sensitivity attainable can be estimated to be 2 . IO-’ g. This sensitivity should be good enough for most determinations of tin in a variety of samples. Amal.
Chinr.
clcla,
30 (I&+)
335-345
DETERMINATION
OF TRACES
OF
Sn
337
Reagents Standard tin sol&on. Dissolve 0.0528 g of pure tin metal in 5 ml of I : I nitric acid along with 3 g of tartaric acid and dilute to 25 ml with water. Standardize gravimetritally by taking an aliquot of the solution. Carrier sohtim. Tin. IO mg Sn/ml. Dissolve x.01 g of tin(I1) chloride in 17 ml of hydrochloric acid, and dilute to xoo ml with water. Standardize the solutiongravimetrically. Holdback cavriersohtion. Antimoq. 0.5 mg Sb/ml. Dissolve 0.05 g of pure antimony metal in 13 ml of sulfuric acid. Boil the solution with 0.2 Q of hydrazine sulfate, cool and dilute to IOO ml with water. Arse?ric. 2 mg As/ml. Dissolve 0.27 6 of arsenic trioxide in 4 ml of I N sodium hydroxide, dilute with water, acidify slightly with hydrochloric acid and dilute to I00 ml with water. Copper. 2 mg Cu/ml. Dissolve 0.78 6 ot copper sulfate in 100 ml of water. Iro?t. 2 mg Fe/ml. Dissolve x.0 g of iron(III) chloride in xoo ml of I N hydrochloric acid. Dissolve I 6 of the reagent in Diet~tylatrr?nolri.trnr dietkylditlliocarbavtnte soltrtiou. IOO ml of chloroform. Prepare just before use. Iso)robylacetom. (CH&CHCH&OCHa. Analytical grade. All the chemicals used wcrc of analytical-grade quality.
Decomjosition An outline Silicate
of irradiated
of the radiochcmical
samples
separation
and
firelinrinary
separation
of
tin
scheme is shown in Fig. I.
rocks
Silicate rocks arc obtained in solution either by digestion with sulfuric-hydrofluoric acid or by fusion with sodium peroxide. For the cligestion, transfer an irracliatcd silicate rock sample quantitatively to a so-ml platinum dish. Add 2 ml of tin carrier solution, 5 ml of 18 N sulfuric acid, I ml of nitric acid and IO ml of hydrofluoric acid. Evaporate to strong fumes of sulfur trioxidc, occasionally adding a few ml of Take up the residue in x.00 ml of hydrofluoric acid to complete the decomposition. water and 20 ml of 25% tartaric acid solution. Pass hydrogen sulfide through tllc solution to precipitate tin(W) sulfide. Proceed as described under RadiockcnticaZ sej5avation of ti7c below. For the fusion with sodium peroxide, add 2 ml of tin carrier solution to a so-ml nickel crucible, then add dilute ammonium hydroxide to precipitate tin(IV) hydroxide and evaporate to dryness. Put the irradiated silicate rock sample into the crucible and fuse for 5 to IO min with G g of sodium peroxide. Dissolve the melt in 20 ml of hydrochloric acid and dilute to 200 ml with water. Add 20 ml of 25% tartaric acid and pass hydrogen sulfide to precipitate tin(IV) sulfide. Continue as described under Radiochemical sefiaratiott of tin. Sea
water
To recover tin in sea-water samples, add 30 mg of iron(II1) to a 2-l portion of sea water containing 40 ml of hydrochloric acicl, heat and precipitate iron hydroxide by R7ral.
Chim.
Ada,
30 (19G4)
335-345
‘al
L
Y Ir,
u
w
;_
I
HIS.
Add Sna+ carrier. Fuse with Sa202. Dissolve in HCI. Dilute, add CIHeOs and pass
I-.-_-.-
Add SnJ; carrier. Decompose with H9,S04-HSOa-HF and evap. to fumes. Take up in H&, add &He06 and pass HZ’%
---
Silicate
SH:OH.
_-!-SnS2 ’ _.-.--._
HaBOakd pass HG.
I ; Aqueous
with isopropylacetone.
and add Feay carrier.
.-_ _.. .._..
..^ -..-
of
Fig. I. Chemical separation
Ignite add weigh.
hl%,!j
scheme for tin.
Dissolve in HXO~-HC~OJ and crap. to fumes. -- I
Add HaBOa and pass H&L I SnSl I .-
Back-extract Ato 2-5 _Y HF. I ._ -..--. Aqueous,
Dissolve in hot Hk0~: SeHaSOd. _-kid SbJ’, ;\sa~ and Cu”+ carriers. Diluteandestract with CHCl& (C?Hs)~SCSSSH~(C~Hj)~. _._-L_-\qucous I Add KI and estract with isopropylacetone. ._._I ---Organic !
Add
Estract
sps,
.F--!--
Dissolve in HCl-HF
__.’
Irradiate for 3 days. Dissolve in HCI. Add Sna+ carrier and C4H&. Pass H&k /
Fc(OH)s -/--
Dissolve in HCl and transfer to another 2-l portion sample. Repeat precipitation _I times. I
Fe(OH)ai -___
Sea water ------Add HCI, 30 rng 1% and then __- I -
I’usc with Sa:Oz. Dissolve in HCl, dilute, add C4H&~. and pass H&.
Add SnJ+ &ier. Decompose with HS03+ H&04. Add HClO( and cvap. to fumes. ---- I SnOz
-. _...--Biolo4cal material : _ .__” Add SnJ- carrier. Dissolve in HCIH2S04-HSO~. Dilute, add C4H60e and pass H$.
Jkroalloys -i -. -.-
..___.
!
DETBRMINATIOh’
OF TRACES
OF
sll
339
dropwise addition of x : I ammonia solution. Dissolve the precipitate in 40 ml of hyclrochloric acid and transfer to another z-1 portion of water sample. Precipitate iron hydroxide in the same way. Repeat the precipitation 5 times to recover tin from 10 1 of the sample water. Wash the final precipitate thoroughly with 2% ammonium nitrate solution, dry and irradiate as mentioned above. Dissolve the irradiated iron hydroxide in zo ml of G N hydrochloric acid containing 2 ml of tin carrier solution. Adjust the acidity to about I h! in hyclrochloric acid ancl precipitate tin(IV) sulfide as described above.
Decompose the irracliatcd biological sample with 3 ml of sulfuric acid and q-ml portions of nitric acid in the presence of 2 ml of tin carrier solution. When the dccomposition is complete, adcl 3 ml of perchloric acid and heat until white strong fumes begin to appear. Dilute and filter the precipitated tin(IV) oxide through a filter paper. Fuse the tin(IV) oxide with 5 g of sodium peroxide, fnllowing the procedure described for silicate rocks.
Transfer an irradiated sample of fcrroulloy to a so-ml beaker containing 2 ml of tin carrier solution, 20 ml of 6 N hydrochloric acid. 4 ml of 18 N sulfuric acid and 2 ml of nitric acid. Heat gently OXIa hot plate until the sample has dissolved. Filter off the residue consisting of graphite and dilute the filtrate to 150 ml with water. Add I to 2 g of tirrtatk wit1 zinc1 precipitate tin(IV) sulfitlc iIS before.
Dissolve the tin(IV) sulfitlc in 5 ml of hydrochloric acid. Add 2 mg of iron(lI1) carrier, 5 ml of 2.5 N hydrofluoric acid and 5 ml of water ancl shake for 30 see with 15 ml of iSol’rO~)yli~cctOlle. Drain the ilClLlC!CJUS pIliWe (lower) into a So-nil centrifuge tube containing IO ml of saturated boric acid solution. Pass hydrogen sulfide to prccipitntc tin(IV) sulfide. Centrifuge and discard the supernate. Dissolve the precipitate in 4 ml of sulfuric ncid in the presence of 0.2 g of hydrazinc sulfate, and 2 mg each of Sl++, A++ and Cu2+ carriers. Add 22 ml of water and extract foreign activities by shaking with zo-ml portions of dicthylammonium dicthyldithiocarbamate solution in chloroform until the color of the extract disappears. Add 5 Q of potassium iodide to the aqueous phase and extract tin(IV) iodide by shaking for 30 see with 20 ml of isopropylacetone. Wash the organic phase twice with ro-ml portions of 1.5 N potassium iodide in 3 N sulfuric acid. Strip tin(IV) iodide by shaking with IO ml of 2.5 N hydrofluoric acid; 20 set is enough for stripping. Add 15 ml of saturated boric acid solution to the aqueous phase ant1 pass hyclrogcn sulfide to precipitate tin(IV) sulfide. Dissolve the precipitate in a mixture of I ml of nitric acid and 2 ml of pcrchloric acid and cvaporatc to strong fumes. Dilute with water, filter the precipitate through a filter paper, dry and ash. Slurry the tin(IV) oxide with a few ml of water, transfer to a weighed small filter paper, and wash with water and then with acetone. Dry at 1x0” for 10 min, cool and weigh to determine the chemical yield. Mount for the activity measurement. Treat the comparative staxzclarcl in a similar way. .I ml. Chim. ncrn, 30 (1061) 335-345
340
H. HAMAGUCHI,
K. KAWABUCHI, RESULTS
AND
N. OSUMA,
R. KURODA
L)ISCUSSION
Separation of tin from arsenic, antimony, molybdenum and tellurium presents the most difficulties in thcradiochemistry of tin ll.The isopropylacetonehydrochloric acid extraction system has been found effective for tin(W) but it is not spccificl2. However, most of the intcrfcring elements in this system can be removed by extraction with a solution of diethylammonium diethyldithiocarbamate in chloroform from sulfuric acid medium; this leaves only tin(IV), antimony(V) and arsenic(V) in the aclucous phase l 3*14. Extraction of antimony and arsenic can be achicvcd by reducing to the lower oxidation (trivalent) state with, for example, hydrazine sulfate in sulfuric acid solution f.6, which leaves tin( IV) unchanged. In order to shorten the chemical separation, an attempt was made to extract foreign activities by isopropylacetone from a solution which was 6 N in hydrochloric acid and 0.8 N in hydrofluoric acid, the tin remaining in the aqueous phase. This extraction can be omitted in the radiochemical separation involving silicate rocks, materials, because the carbamate extraction sea-water samples and biological followed by the iodide extraction- stripping system provides a satisfactory separation irom molybdenum as well as from most other contaminants, including antimony and arsenic. However, the first isopropylacctonc extraction is an essential step for ferroallays, particularly if they contain appreciable amounts of molybdenum as an alloy constituent. For high-molybdenum alloys like SCS 14 steel in Table II, additional puri-
Ttme (days)
Fig. z. Ikcsry curve of inducctl 121% activity isoldccl from an irmtliatcd steel. (Ia) Gross tlccay of compnrativc stnntlnrcl: (Ib) lzlSn tlt!Cily obtninctl by subtraction of long-livccl frnction in compnrntivc standard: (IIn) gross tlccay of tin nctivitics isolatccl from the snmplc; (IIb) 121% decay oldaincd by suhtrrrction of long-lived activities in the sample. .*Irlcrl. Chiw.
rl c/n. 30 (rgG4)
335-345
DETERMISATION
341
OF TRACES OF %I
fication is necessary in order to obtain radiochemically pure tin(IV) oxide. For this purpose a single scavenge with molybdenum sulfide or a-benzoinoxime is effective. In Fig. z a typical decay curve is illustrated for induced tin activities obt’&.i%d from an irradiated ferroalloy sample. Analytical results for several kinds of ferroalloys are given in Table II along with the main constituents other than iron. In the same Table are listed results which have been obtained by the present authors using an activation method of analysis accompanied by chemical separation as reported by LEADER*~ (abb reviated to “precipitation procedure”).
0.45
3.23 0.50 0.32 0. I .j
0.M
12.17 ‘7.78 2.31
(J.5178
168~
o..?r3q
I f>S”
0.2513
101
0.3Mib
IIC>b
l
0.3030
53.5’
0.2007
s7..5h
There remain problems in the conventional analyticCal procedures for traces of tin in silicate rocks. Values for tin in the two internat,ional rock standards C-I and W-I provide the evidence for this point (Table III). It can bc seen that the agreement in values for tin is not very satisfactory between analysts. Further evidence may be found by literature surveys on the abundance of tin in materials of geochemical interest, in which markedly controversial results have been reported. For example, GOLDSCHMIDT AND I%*reI@S gave a spectrographic value of 40 p.p.m. Sn for a composite of 36 European Paleozoic sh‘ales, whilst ONISHI AND SANDELL~~ found calorimetrically the much lower value of 5 p.p.m. Sn on the same sample. A matrix effect in spectrochemistry or incomplete decomposition of silicate materials (or a reagent blank) in wet methods could be responsible for such controversial results. Activation analysis with a radiochemical procedure involves the assumption that the radioisotopes induced arc in an identical chemical form with the carrier which is to be added. In the development of the radiochemical procedure, we first tried to find a proper method of attack for silicate materials, because certain tin-bearing minerals Anal.
Clritn. Acla,
30 (19G4) 335-345
342
H. IiAhIAGUCHI,
K.
KAWARUCHI,
‘l’A131.15 VALUILS
-_
TIN
ONUMA,
It. KURODA
III
IN G-r
ASI)
IV-1
_.
G-r (p.p*Itl.) --_.-- -._...-...--’
r;OK
N.
‘2
IV- I (P.P.,rr. J
______.__ < ‘2
5
_--
2.3 (av.) 5. I (av.) 8.8 (nv.)
2.8 _--
C.5 .< 210 3.3 (at,.) 3.4 (xv.)
. . _._.._..._. _______ ___ _.. _. _.
(av.)
x.7
(xv.)
2.5
(ilv.)
‘:s <.,zo 3**1 (av.)
_____- ._._
.._._
. .._...--- ^____ -___-
__..__
Sl~cCtr~~ClIcIlliCilI
Sl’cctroclicriiir;il Clwmical Spcctroclicrnic;ll Sl’cctrocllclllic;iI Spcctrocl~crnical Spcctroclicmical C:hctnical Activ:rtion
like citssiterite in silicate rocks arc strongly resistant to hytlrofluc~ric acicl. In 'I'ablcIV tllc results obtninccl by digestion with hydrofluoric acid anal by sodium pcroxidc fAon ;trc given for G-r granite; tllcre is no significilnt diffcrcncc in results between the two proccdurcs. The s;imc is true for determinations of tin in a biotitc granite (‘l’ablc IV). So far as the usual types of igneous rocks arc concerned hot11 opening-up 1)roccdurcs seem to be satisf;M.ory. In order to dctcrminc tin in se;\ water it is not ackcluate to irradiate? scn. water itself, lxcause of tlw high activities induced by irradiation and of the small snmplc sixc which is limited by the irracliation.space. Accordingly, tin was concentrated from 10 1 of sea water by coprecipitation with iron(II1) llyclroxidc. In orclcr to cllcck the rccovcry of tin, a tin-rzr tracer was added to 2 1 of sea water along with il pg amount of inactive tin carrier (tin(IV) chloride form). Iron(II1) hyclroxicle was then prccipitatecl by tlropwisc addition of ammonium hyclroxide. liccovcry of tin was satisfnctory (Table V), proviclecl that sufficient iron(II1) was added as tlic collector. The overall yield for the collection of tin from I0 1 of sea water, in which tlic precipitation of iron(II1) hydroxide from 2-l portions of SC;1 wntcr was rcpcatccl 5 times, ilVt2IYlgC!Cl C)87/,; this figure was applied as a cor. rcction factor for the practical clctcrmination of tin in sea waters. Values for tin in scvcra.1 sea-water samples are Given in Table VI. The total rcagcnt blank from the iron collector (30 mg Fc:~+, ammonium hyclrosiclc and hydrochloric acid which are usccl to collect tin from IO 1 of water sample) was chcckccl each time; the figures are also given in ‘l’ablc VI. The use of cloublc amounts of hydrochloric acicl (runs I and 2) increased blank values by a factor of two. ‘I’hc blanks arc I~robnbly contributed mainly from hydrochloric ncitl or ammonium liydroxicle. Tlic results of determinations of tin in marine organisms arc summarized in Table VII. .*I ~~41. Chiw.
.4ckz,
30 (I@.+)
335-345
DETEI~NIMATION
OF TRACES
OP
sll
343
The proposed radiochemical procedure is reasonably rapid and gives a high degree of radiochcmical purity with rather uniform chemical yields running to about 50%. In most cases it takes less than 3 11 to complete the whole l>roceclure, because tedious precipitation steps have been replaced as far as possible by rapid and effective solvent extraction methods.
Correction for self-absorl)tion and back-scattering in sources for measuring flactivity is necessary because of the rather weak maximum p- cncrgy, 0.38 McV, of ‘“‘Sn. ‘Tlic correction curve indicates that the combined effect of self-absorption and scattering increases with increasing tllickncss of the tin(IV) oxide sources. In actual the correction was not always carried out because of the uniform practice, howcvcr, chemical yields obtained throughout tile work. Attention must also bc paid to the self-shielding effect of the sample against neutrons during irradiation, leading to a reduction of the cffectivc neutron flux through a sample and causing uncclual acti-
344
H. HAMAGUCHI,
K. KAWABUCHI,
X. ONUMA,
R. KURODA
vation of the sample. For practical purposes, weights up to 1.3 g of the usual types of silicate rocks and r.G g of iron meteorites can be tolerated for irradiationz0s27. To investigate this effect in comparative standards, varying amounts of tin (as nitrate) were irradiated and the induced specific activities were cletcrminecl. No significant cllangc in the specific activity was detcctablc over the testecl range of 104 to 620 pg Sn. ‘The possible competing nuclear reactions, 12fSb (n, p) 12lSn and 124Tc (n. dc) 1“‘Sn, seem unlikely to contribute to the final result unless these reactions have exceptionally high cross-sections. In addition, the elemental abundances of antimony and tellurium arc so low that interference at any significant level is unlikely to be serious. For samples containing an appreciable amount of uranium, the production of 121% through a fission reaction 23fiU (n, f) 12lSn must bc taken into consideration. Although the &ion yield for this reaction is only o.o14~~, I pg of natural uranium gives a lz*Sn activity corresponding to approximately 0.01 /~g Sn under the irradiation conditions stated above. In almost all cases the contribution of l2lSn from uranium fission is unlikely to bccomc serious so far as samples containing little uranium arc concerned. SUMMAI
1Jnc mL(thodc par activnlion au moycn dc neutrons cst appliqudc nu dosngc dc traces d’dtain dans tlivcrs L’chnntillons (Riliciltc%, ciwx dc mcr, substances biologiqucs ct acicrs). <‘c?ttc mdthodu cst rapidc ct pcrmct dc doscr jusqu’tr 0.1 pg d’btain, cn compnrent I’nctivitr! p induitc dc Ia*% (27.5 II) uvcc ccllc d’un dtnlon.
Es wurclc cinc allgcmcin unwcndbarc Mcthodc zur Ikzstimmung von Spurcn Zinn mit Ililfc dcr Ncutroncnaktivicrungsnnnlysc cntwicltclt. Die l’rolwn und VcrgIcichsstandartlR wurdcn insgcsamt 3 ‘I’agc lang bci cincm Ncutrorwnfluss von cu. 3 * 1011 n/cm3/scc bcstrahlt. Es folgtc cinc radiochcmischc Trcnnung mit Tr!igcr vorwicgcnd tlurch Fllissigcxtmktion. Noch o. I pg %inn kann lcicht durch Vcrglcich dcr P-hktivititt dcs la*Sn (27.5 h) mit dcr cincv Standards bcstimmt wcrdcn. IXc Mcthodc iut schncll und hat cinc chcmisclrc Ausbcutc von ctwn 5o’X. Es wcrdcn die Zinngchrrltc von cincr 1Ccihc Mutcrirrlicn wit Silikatgcstcin, Sccwasscr, biolo&schcs Material und Stahl sngcgcbcn.
1 J. 1’. GALI, in R. C.. tiocrr, /tc(ivrcliotl .4rwlysis MnndOoolr, Aciltlcmic Prcns, New York, 19’51, p. 17.2. 1 I-I. MAMAGUCHI, 17. KUROIM, 'T.SHIZIIIZU. I<.SUGISITA, 1.TSUICAHAHA AND R. YABIAMOTO, J. n 1. Emvgy sot. Japrln, 3 (19Gr) 800. 3 EI. ~~AMAGUCHI, I<. I
AND V. N. ZAMYA'TNINA, %/I. .I~nlit. f
London,
1954.
n nrcl. Clritr1. ncm, 30 (rgG4) 335-345
IXTERMINATIOX
OF TRACES OF Sn
1” M. FLI~XX~H AND R. E. STEVENS, Geochim. Cosnwchitn. Ada, 11 W. E. NEHWK, The Radioclremislry of Tilt, NAS-NS, No. 3023, 12 H. GOTO, Y. ICAKITA AND T. FURUXAWA, J. Cicem. Sot. Japan.
345
zc) (rgGa)
525.
1960.
79 (1958) 15x3. 13 P. P. WYATT, A,~ulysf, 80 (1955) 3G8. lj c. L. IdUKE, A7lUl. Che?PJ., 28 (1956) 1276. 1.5 W. F. HXLLEURAND, Applied I?torgatric Analysis, 2nd Ed., \Vilcy. New York, 1955, p 70. Itadiochemical Studies. The Fission 10 G. R. IAADI:R, in C. I>. COHYBLL AND N. SUGARMAN, Producfs, 13ook 2, Part V, McGraw-Hill, New York, 1951, p. 919. 1’ K. K. TUREKIAN, Science, XZG (1~57) 7.)5. 18 A. A. Cno~os. quoted in ref. g. 19 H. ONISHI AND 13. B. SANDELL, Geochim. Cosmachim. Acfn, I 2 (1957) 262. 10 N. HKRZ ANU C. V. DUTRA, Geochim. Cosnrochinz. Acla, 2 I (rgcjo) 81. AHICENS AND S. R. TAYLOR, GeociJinr. Cosntoclrirn. Ada, 18 (1960) 162. 21 R. R. IhOOKS, I,.1-I. 12 TH. I-iUcI, quoted in ref. IO, ss written communiczLtion. Cosmorhim. .4c/u, 20 (IgGz) 51 I. 23 M. C. CLAKK ASI) D. J. SWAINIS, Gcochim. zJ I. ~AKhlIcIIAISL AND 11. ,\rCI>ONALIJ. C’COCkit?Z. COSmUChi,,,. .4hZ, 22 (lgf>l)87. Ia \'. 31. (;OI.DSC~ISIIDT AND C. I’ETISRS, Nuclir. (;es. Lviss. Giilfi*JgeBJ, iTlath.-physih. kehSSC 111: 30; I I’: 37, 278 (1933). 23 H. HAMAGUCI-II, G. M’. REED AND A. TUHKKVICI;, Geoclritn. Cosrt~oclrint. Ada, 1;1 (1957) 337. D? I-1. I-iAnlAGUcHI, 1‘. NAKAI AND Y. l
.4 eta,
30 (ItJc,q) 335-345