159
PREPARATION OF ISOTOP1 CAI.LY F.NRJCtiLD SAMPLES OF IRID1UM, OSMIUM, PALLADIUM, AND 1'LATINUM FOR RESEARCH USE
K. W. McDaniel, L. 0. Love, V. !'. Prater, R. L. Bailey
Oak Ridge National Laboratory Oak Ridge, Tennessee 37330
Abst me i
The .'\ ;:;'.' i fluorination technique, which is currently be ins; employed at Oak Piiire National Laboratory for enriching the stable isotopes of iridium, osmium, palla- dium, and platinum in electromagnetic isotope separators, is de-scribed.
Ion-source modifications and safe-handl i .nj.; procedures for usinj; chlorine trifluor- iue (the fluorinating agent), both necessary for successful separation, are given in some detail.
It is suggested that the internal fluorination method might be used in smaller lab- oratory separators for target making by depositional methods.
Simple chemical recovery and purification schemes are i'.iven for each of the four elements, along wi'\ some of the current uses of the nuclides in research and me d i c i n e .
-A Research sponsored by the U.S. Atomic Energy Commission under contract with the Union Carbide Corporation, Oak Ridge, Tennessee 37830. 100
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i\a' :.:i: •.' ' ..si's Liu ft1 has r>;isU:J a need I'M' separated .iscti 'pc.-^ o'. the p S it L; ,ui"
;. - s-._ > i i •. i ••! , indents, e,pedal ly I'or tiie study o! v.ii:ii-i;: inrit.ij- ;r porties. L'J.LIJ
. ;...•.-.' ti ;a:iicjuv du vv i u[)i.' J !"!.-'< t'I;/. !y a; i •]•:'.';., pat t''i':;i ..i a] L .. r tia. \'.\.-: -:. i .ia a ua'1 .^! i--11-:..<.•]; J a r .' i iLiorJiiL'" and iJiv.i.'.i i::-.'-- ij: v.Li ., ut i 1 i /..v; f. i i" . (..! i\ icl witii a;:d uraa^pi ia piatinui;; and p lal i luini-^r^ap niclais d i iv t 1', iat- tau i on i zaL Loii rL-'i'Mi •.'1 tin.- i .-.! lit. ri);: i uii suurcc. iaiD:parud Lu tin- •.- U c 1 ron-a<:%harU:-,ia: t ':; ,;a -Cfi:.peraL i:rc :::''liiod a 1 :u.'parat iai'.- p laL i nai;!-;!!*.1 La Is i L-L-L i>p<> , i.i-- -:-u r'tv-n t L--. '•; i: \/.] uu has r.. v j ] u- I i oiii Zi.'ci i.lu- saparat. i ens oi Liu- p 1 ;;t i i'.uir.-i'.v i. i! is.-Lipas (u:;pi.'c !.••'! Lv i r i d i una in ; • I'I • ail !ia t aad i s ; t • > p i c put: i Ly . (Ire a L ca" o '• • a'- : : ; 11!:> •-1 : r i a i nr , isri ur:, j\:: ; a a i m~., .•HI'.; p!ati;:nni .na- ,-•: i-r-.1 »t ly fcr SDI.II iili ;U') a.-.: i ! .I'.I I ^ it IIIV/HT ist't.pi.' parity ! :i-.iu L ia'ii^a t ! ^a.M ;: ]L i 'a.1-, i a ,i;:.;ri [ i ;:;L- ,I^;I> .
ia1 ; I i;a if L nat i ;a; :\L- t. aad in :a • i ii;' aSL- d in p raaiK L i L;II- t. vp./ s^: p ;rat > a ^. ; jr t iir rurov- ci'v i I /. r.in ipian t i 1-ias ui must, DI' Lin.- :su'i'[v-i; ;n)Wc\-L-;', ti'^iv appears [.;"•• bu no r ^ •.!,-•• = 3; '.vir: : iu- t t.'i:i; ni-qut' C.MJJ(] not i-u- a.-.t-d , ri :a:^a 1 1 S'.-pjr.itt.'rs v.:a.-r^ L-::;piia.sis is p:a.... V a-.t..'d !i'i tiu' ' raiisiii 1 .ss i on J t CC 1;, Lu L i: L c:iar;j.c iujLtiL' -.•.'.'is Vvp I aci-d v/iLh a nickel ! : in lur !iii-: L ranmia s>; i i n at" |_. I 1-', I're:. ,• cvlindar niuuntvd nn the ii i aa-vo] tage tcr- iiiia.ii bo:-: aiia.TLly inLo Liu- '.>.ii-k ui tin.- ar/ ciuiir.iio r wiiii-ii aoiiiaineJ the eJcncnt ( is iiiflal) ;.)i.-in>: p rinL'Ssod; iiccaasi.- <;l IIK1 1~COC L i on be LWI-IMI grap'nite ar.d Clr-j and p. ss i i.. 1<- n-ai.-t i oiis but'.-.'ei.-r. p 1 at i nun-aela J c .or:,;:aa:nds and j-,rapl> i 1 e , a. nirkel liner •-.I.-; i aii i" i ratt-d to cover tiie inside surfaces of the :n"t. chaniber; the nickel linei' •...is ]!i-r! iiiati:i! vitii l/3_!-in. iioJes every i/'-i-in. to providi- a more unilrrn f 1 ..-,<- ii[ ill. tiV'-r Liie netaJ.j tile oven heater was eiini naL.d; ti;ub the i on Lzat ion arc and i.u- < ititrorj drain supply 1 roiu tue sourco were couiitea CMI to- pro\-i(:e sufficient a---.il lor LIIL- iau-r.iicai reaction lietwcL-n tile kll-". .aid meL-.tl . ALuj\e tile vaporization Leiiiperal ure .1 tile metallic fluoride, tile rate of ia.ac.tioii vas , i.;i (. roJ 1 ed largely i.y tile : !. iv rate o! (.IF; which •.-.-, is regulated by a n.eterinj; vaivi outside the ion Al l;:.m,;:i C i F . is toy.ii: and ii az ardous , as a resnl! ef til-.- adu-p t i i in ui a very ri^ : set oi n.uidii n;.', procedu rus , no inei dents have been experienced in tile use of tilis ^ja.s . Figure .1 siiows Liie precautions t aive n durini; rvir. tern: nat i ons , lilese pro- cedures were instituted durin;.!, sliort du ve lopr.ent runs with tiie advice and approval • a tiie i'lant Industrial Hygieni (Iroup. As a further protective me ch,m is:?i as we]] a.-, .u; aid to reducing tank pressures, caiciun; metal was vaporized at tiie rate oi 1-3 :' Ca/br. into l.iie lar^e '.'acaiun sys tei;: vnie.n i'l}\ was beim; used. \ . V . liueiin, !i . V.. C.avr i I ov , ai\d V. :> . Zojotarev, :•'. i •. •': i roaiu^nc t i c Separation of tiie isotopes •:•;.' tiie !' 1 at j nun-!'.!! J adi ur.i Croup, 1 soti.penpra>: i « 7(b): 23d-5 (19 71); i ii loass i ;ii:. 161 HIGH-VOLTAGE TV TERMINAL PI METAL AND/OR SPONGE ION CHAMBER Fig. 1. Fluorination System for Calutron Ion Source. Fig. 2. Precautions Taken During Run Terminations. 162 Table 1 COMPARISON OF ASSAYS USING FJJ:CTRO.\' UUMHARDMJiNT SOURCE AND FLUORINATION WITH GIF, NA "Bombardm ent" "GIF/1 U) (%) C.) :•)• Pt 0.0127 0.76 4 .2 1 !; i't 0.78 n.s 57.3 •'•"•l-t. 32.90 65 .0 93 .9-97.4 i ."Tt 33.80 60.1 9 7.3 : !•• 1>t 2 5 . 30 65.9 9 7.5 - l:i\'t 7.21 60.9 95 .8 XUN DATA: Time 4,769 lir 4,400 hr Recovered 64.9 a 176 .3 !•, ::.!,,. 37.3 9 4.66 9 7.1-9 8.2 i ) .'. | r (.2.7 9 8.7 96.9-99 .4 IUN DATA: Time ..,471 h r 2,600 hr Recovered 2.7 g 151 .0 g i.cule 1 is .i Lable comparing the outputs and purities of the GIF-j system with the electron hiiir.bardment method. Chemical Recovery and Refinement of Enriched Platinum-Metal Isotopes Iridiuni, osmium, palladium, and platinum isotopes are all collected on fabricated, ii iyn-p-.iri Ly graphite receiver pockets (receiver is shown in Figures 3 and 4). The cnriihcd material is recovered in each case by the simple expedient of burning i mlj i' idu.'jl graphite pockets, in oxygen, after removal of any neutral or adjacent- iHoLupe material from the outer surfaces of the pockets. Iridium, palladium, and p 1 at i unuiii isotopes remain in the quartz ignition containers, along with any graph- ilc impurity, as relatively pure metals. Some oxide is usually associated with tiie iridium and palladium deposits. Osmium, however, forms a volatile oxide Vi>,[), u.p. 121.2°C) during the ignition step and consequently must be chemically trapped for further recovery. 163 Fijj;. 3. Osmium Receiver With Faceplate. Fig. 4. Osmium Receiver Without Faceplate .16-3 1 rid i uiv : r id i u:.. I .-. .'Hi1 i'! i;i> .:<>ie dillicult tlr-tnts t .-• reii;:<- !r ,, p,:re .-•'..;!.• ;> r i ::.•: r i ! y . ;ijr Li1 t;: i Vi r .' 11|[.-.' so! -Ui i i i t\ o i the mo L .11 (jr ' -x Kie ) in c i t_' K t :;; ii: ] v '.• r t'.ii :•:-.<; .:'-u.s. Ii: aduiLion, since there are no sclfctiw precijii l..-;i;l.s i.iiown ]i>r 1'L-;:.UV i r.i1 i r: uii n::. 1 • ~ '•.-. .i les'.iit v-'i tiie associated .soluiiility res t r i r t i i. ;:s, earii ol tiu1 l:.'<. isoteje.-, !.-/••'I .jiui -I'M) wa.s iioi:;:ji;e;>i zed by liieciian i r.il ly stirring tiie sai:ipleM i ii va'.ei :'• r uj' Le 7.1 ..LMII'.I L-.uii. liiis technique, although ordinarily uncies i rab 1 e, v:as .Ki^rt l.r tvo reasons: (,1) pru11 iir.inary mass analyses ol 15 individual sanijiles ..-in;.-, t i- tul ii:,,1 e.i;:ii i..iiUi|'iv lot diilered by less liian j t;r,is:-; jjerreiit, thereby es! ab i i s.. ii:.-; .. rear. • i:a:-1 e ii;:.)t. oJ i nhoir.ogeile i t\r, and {!) .ivaiia'jle dissolutiL'n r:e liiov:^ •.eie v-'iis i de i"e;i .. iLaei" teo hazardous or :nade'[uale !"or tiie larye sariMe sizes. i -le:..! •. .i 1 IVI'i ne'..;ei'.i. v:as ae coinp 1 i ;;ii ed by renioviiiK soluble in.purities by K-av.-., i;i>; 1 e, iiiii'jne.s r.iLinv tnan !)V Liie usual prut, ip i LaL ion methods. Foliuwirn; a ny drr>'.'-T. re due t K-n at til)0"L to entail", tiie most reacLive ion:! el as many i;..pur i. Lv ele::;ents pessiijle, eaca HI Lue i so Lopi ca 1 Ly enriched samples uas LreaLed first wit'n iiv! 1 iH •iil'.ile ( i : 1.) nitric acid and then i-.'ith Jilulcu hydroch 11 •y i c acid; t.ie n;e t a i was .i.isaed al U !' each step- wiLli a 1,'. solution o I" M-.,(;] . '1 ne liquid was separated iro iae ii. a. ned i^e L a ! by cen t r i t '.!j.;at ion , and the irceLa! v:as air-dried a i I ..• r vasi: l i-.i.1, .. i t a ,ii-i I one and etner. It vas Cinally re-:educed in hydrogen at 'JUl'cC to obtain :''ri>.at, si^inv, i.ieLaliie i r i d i urn. i he' metallic sai::pJe.s wei'e ccoleii in a 1 1 ew oi .ii";.o:; L.; j-re'.ef.'t ;>..' ->.s j ;:• J e adsorption ol hydrogen. Osmium i he chemistry ol osi'.u um is dominated bv one compound, tile Letroxide, Ost)^ , bec:iust.' il is both volatile and toxic - properties that have to be considered carefully in tiie recovery and refinement of the isotopes in order to prevent losses by volatil- ity and avoid exposure of personnel. The oxide, for example, can be formed even at ! ov (ei;;per;)t ure when finely divided metal is exposed to oxygen; it is also forme J .-.'hen Liie nie t a 1 or one of its compounds is boiled in nitric acid. Osmium tetroxide : as an appreciable vapur pressure even at room temperature and lias to be handled v. itii i . • prolerabjy in a closed system. Its vapors arc poisonous (maxiiTiim per- ::;i;Ud at inospiie r i c level 2 x l(_Tf:> g/niJ) . It attacks the eyes, causing blurring ui vision and, in severe cases, temporary blindness; it atso attacks and irritates tiie nose and throat linings and may aggravate bronchial conditions. As ::,eiitioned earlier, osmium isotopes are recovered initially from graphite collec- tor pockeLs lv ignition in oxygen, which oxidizes osmium to volatile 0s0L and tile graphite, to O), . The quartz combustion train (Figure 5), fitted with ground joints and .leaied wilii Kilieone grease (which does no_l_ reduce OsO ), includes three sequen- tial i.-jiei.i i ral traps which are partially filled, respectively, with, concentrated iiir + Nl!..!;r (u g/g of Us estimated), 1:1 lilir, and an alcoholic solution of KOH. An oxygen flow is begun and heat applied to the quartz Lube by means oi an electric lube lurnace. An appreciable quantity of 0s0:. appears just under 300°C as noted by i he dee.p ridden i ng of the first trap of concentrated liBr. 'Ihe ignition is continued until all she ;:raph.ite is consumed at ' 800 °C. 1G1 Fig. 5. Combustion Train foi Recovering Osmium. •-..• !M',r I rap scluLiuns are conbined and the solution is evaporated to near dryness •I; a steai:i ii.u;]. iJilute (1:1) 11C1 is added to ttie moist salts and the solution is )"'-ev.:;>i'r.iled to near dryness, (This conversion to chloride is made because Osti it". |'.i:'ed I )"ur,; liiloride solution is easier to wash and reduces to a cleaner metal.) .';•; ,n::,::i!ii i u!;; s;ij t i .s added during evaporaLion to )irevent loss o 1" osmium. i ...- a :;i::'>n i ui:; ch 1 oro-usma t e salts are dissolved in distilled water and the resulting .w'.mie;: is ireated dropwise with saturated NaliCO; to pli .'*, at which point a black jTri.-ip i lai e oi iiydrated OsO-. appears. The solution and precipitate are heated to '.)• • i 1 . u;.\ I., ensure complete precipitation. iin. ..it.-:-: i t], • is separated by cen t r i fuga t Lon, washed free from sodium ion with a 12 -.olui. ion ..I Mi.,Cl, and finally allowed to air-dry. The dry OsO- powder is trans- ;i-rr..-;i I" a quarts bo;:L covered with Nil.,t'. 1 and moistened, reduced with 11 at 900°C, a:: ••: tin:; a 1 I ov.''.d to cool in an atmosphere of CO • which appears to protect the metal i i\.<:. it ..;•: ic.it i"!i . 1'al ladi ura -.ii- JVI •••.'<. ry .i:d re) i ncr.cnt of palladium isotopes are primarily dependent on the ease- wit;: wiiuh i-Ki:iental palladium is reduced from solution with forraic acid. I'iu asa resultii!;-, froin the ignition of the pal ladi urn-bear ing graphite collector pui.i-.ets is moistened with formic acid and waraied to destroy the surface coating of ;ii'o\;:i palladium oxide. (The absence of 1M0 appears to enhance the solubility of palladium.) the residue is boiled with concentrated H.\'O-, until solution is essen- tially complete. iiie solution is then evaporated to near drynoss and taken up in y> v..\ •'! aqua rei'i.i. Alternate additions of concent rated lid and evaporations. 106 v.'itli formic acid, na::pk'tw Lin.- V 1 at i nun . .• :T,-;',vrv and re 1 i neir.en t of. platinum isotopes, like (hose ul pa 1 I .'.di uv., are ,- j . •:,( •t-.w! .wj the rt our ih i 1 i tv ot the element fro::i solution with forn.ie ,'ici-:. ..::<• r iv;.,i'va 1 iM so[u;>k' impurities Lrom platinum residues wilh diiute nvdr. <•:>!'::-'.• : • : i;i[)"ii- .ji:ids, wiiii appropriate water extractions alter each (. re a 1. me nt , v i .it ; •: u- i.. dissolved liy boiling with aqua rogia. The UNO-, is eliminated by success i \ * .••. : •i.;I ioiis \-.ril!i concentrated UC1, iollowed by small additions ol formic acid. i:n' :,. :i!f!i:v, sn] ill iun is neutralized (p[l - ' 4) with Nai)ll and platinum is ji ret' i \< \ i .:( -.- : . •. .nidiiif: lonaic acid and boiling- (Nalill is used instead oi Ml,,()l! in order [•- .i.-..ill pr.T i p i tuL I on of ammonium cliJ uropl at inat e .) : I at; mi::, ;:»•(.•]) is separated by ceil t ri fugat ion, is washed with a 2/ solution . .' '.::,i.'i [.i i'ei:i<)ve traces ol' sodium, is air-dried in the centrifuge tube, then re:.- .- - :•• -i -'.u-.i Lz oi" Vvcor disli wiie re the sample is i inal ly heated to 8')n°C, a». i-.h ic:i ,- int. n! uiiium assumes the characteristic metallic gray appearance. L'.si-s of liii.' iM at inum-Metal Isotopes in Research "-.,[..-ii.;i: .ill el I'uc isotopes ol the polynuclidic platinum-metal eler'-jnts .ire des i r-. in .-.I.:", ';u.ml ilies lor studies of miclear structure by the (n, :)reaction, os;ji:i::: .•-u! o'.ie:; are currently drawing the highest interest due to their invv 1 wr.ic-nt in .tiicj.-ar ..i i rono 1 o^.y studies proposed by U. 1). Clayton in Astrophys. J. 13^', b^7 I. >ii,.,j ,md Nature J24, 56 (196'J). Specifically there is an urgent need lor care- i • i i !y Ei-.isurcJ '"'Us and '" 7Os neutron-capture cross sections in the keV lo sev- • r.i i -liunureii-ke V range . :., .:.i-.i i L i on to nuc I car-meas uremeiit studies, highly enriched '*Vl is currL-iuiv i i:u .,'.,. u.-,e a.-, Larg.et material for the production of iJ-mPt which is being used in ::u:-le.ir i'.;eri i c i ne . The 4 .0-day 1''' ITil>L lias gamma emissions of 99 keV (11/'.) and 1J> • ••''.' (l.ti, ) that make it suitable Cor whole-body counting. Following Professor .'.. group com- ri-.iii!', cak Ridge National laboratory. Oak Ridge Associated Universities, I'n i vers i • i I'Miii'ssoi1 MemoriaJ Research Center, and the OR.\L Biology Division has been or,-,a "ii.-..id 1M study platinum chemotherapy. Our participation (i.e., ORNL Isotopes ! • i •. i •. i i jji") in this study program is lo supply the target material, provide ado<;u.!i. > ,'Ul :•'•;; irradiations, and systhesize and provide the radi opJ at inum-1 abe 1 ed cor.'pou.u i •-!.'•!-'•') 7 7 , "Nucle/ir Medicine and liiomedical Kadioisotope lecimo ] ogv ml iiil v -l.'ecci;iber 1973," i . K. I'oggenburg, May 1'I74.