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Determination of thallium in biological material1
h
tn
m
zi c:
9
i*’ h
l-i
A.
358
VOI,. 21 (ICJj5))
I~YFVEI
AS 11 1<0ss0*l-l7’ “. ‘I’lwir data also suggcstctl, that l~ytlrocldoric acid wry pcobal~ly could Ix rcplncctl II) ;L sulphric acid solution containing I .1f sodium cliloriclc. Rcestraction of tldlous cl&x-itlc into water is Cxsily xcoml~lislwcl. In tllc final cxtruction step tlitlrizonc is aclclccl in wnmonincal solution in or&r to rccluco intcrfcrcncc from cllloroform-soltIhlc impurities prcscnt in clitllizone. ‘l’ldlium ditllizonutc and some csccss free clitllizonc arc c_stractctl into chlorr~forrn. Most of tllc free dithizonc is rcnwvccl by two wasllings wit11 8 dilute ammoniacal solution; the mimnt rcrnuinirlg in tlw cliloroforrn phw clots not il.ffC!Ct tile tlcterrninntion of tll3lliIlJll. ‘1’1lC (3)rltcnt Of tll;llliUJll iS Ci~lcllliLtC~.l fro111 tllc iLl~S;orb~LllC~ il.t 510 Jll//.. AbSoI’ptiOll C111’\‘CS for ditllizom! ilnd t1liL11illJll ditlliZOlXit,c iLW StlOWll in I;ig. I.
550
600 ny
‘I’llc clctcrmination of tlliLl1illlll, iLS outlined il.lIOVC! (prou3lurc A), is sufficiently specific for most purposes illId iS lX~~~~lllll~tldC
Analyticd Statwl.
rite,
rcxrycnts antI Khss-clistillctl water arc risccl tllrouyl~out, Cxccpt wllcrc oLlwrwisc should bc csclutlctl tluring all work wit11 solutions cont;rininy: cliloriiic.lry~~ocl~l~~tlitliizonc illltl tliiillilliil tlitliizoiliitc. Coiwi?iLctit clcnnlincss is rnosl iiiiprtant in this type r~f Ikryli&t
work.
DigcslioJr
.%/2~~b’fdiQ’
fl~/Jtir’fllffs, JJdS,
/Ill,
:uxortling Gikoll
lllldt2\,
to
I
as
50”
, 250
125
;Lll(l
311.
0111~
in
il
filiE?i
SC~XlGltill~
fllllllClS.
RC~CWJUCS p, 3G5
chl
JJiJlg
O/ ,$USSfUlC,T.
iisc the tligcstim
pwvicms
Cotllllllllliciltiol~~~.
ilrc 1lSctl for ;rppnmtus IS lmilcrl
stcqqwrs
fI:Wl
with nitric ilCitl, am.1 lxfurc the iicst irll;LlySiS Imilctl with watci . Scpnriiting fuiincls, including grwnd surfaces, mltl other glirssw:rrc iwc clcanccl witli raw, pWfCril,l)ly cliloriiic-cont;rinill~, hytlrocllloric l citl and tlicn rinsctl wry Cil,rCfUllY with warm wrtcr nntl tlistillcrl wnlcr. I’iKJl/iJfJJJ SfflJJdflJ~~. I 1116 ‘l’l/llll. ‘l’lli\llOUS nitrate (65 1 .7 iii&) is tlissolvcrl in water irlld tnadc up to 500 ml.
IllId
AfLcr
dcscril~ctl
.
360
A. DYFVEI
VOL.
21 (Xcf~cj)
Flask anti filter are waslrcd wittl 50 ml of water (altogetller 100 ml of water arc ~ltlccl) a~~1 socliutn chloride (0.5 g) is adclccl and clissolvcd. I-Iypocltloritc solution (:! ml) is aclclccl in portions with swirling, followvcxl after mising, by cthcr (125 ml). A roam1 cylirttlor is put lxncatll onch scprrrating funnol to catch any drops escaping. ‘l’ltc prcssurc stlould always lx rchsctl bcforc shaking when ether is present. The fxtnrtol is t l~cn shaken vigcxrtusly for txo min. A moistcnccl potassium iodide-starch lxil)cr shows whit tlic val)our pl~se contains im cxccss of chlorine. After a minute tllc wa.tcr pliasc is run into 1 I. Clrlorinc solution (io ml) is A_Ictl to tllc cthcr in I, wliicll is sIdxtt for 15 sec. ‘1’1~ \ViltCX l>li;Lsc is coml~inetl wit11 the first water pllasc in I I. I, containing an ctllcr solution wit11 most of tltc thllium, is stqqxccl. (its stem ant1 tltc cylinclcr lxacuth it arc rinsd). I-fyIxxliIoritc solutiotl (2 ml) trncl cthct- (05 ~1) are acltlecl to 11, whic11 is sliukcn \~ig0tYNlSly for 1 mill. ‘I’hC W1t.W ])haSC k C~kXlrCk!C~. ChkJrim2 S(Jhhll (20 ml) k XkkCl md I I is shalicn for x.5 sec. ‘TIE water pltasc is again discnrclcd ant1 tllc etlxrr ])llilSC: cotnl~ittetl wit11 the first ctlicr whition in I. I I is rhsccl with iI_ small amount of ctltcr. ‘l’lic collectccl other cstracts are s1x~lccn vigorously for x tnin with sttll~l~~sr~Ils acid (15 ml). A ttdstctxd potassium iodictc-starch pupr, maclc blue dx0~c ttic chlnrittc solution, is hclcl in the vapour pltusc of I. Sulplntr cliosidc gas sl~oulcl lx present ~llost of tllc in csccss and l~lcacl~ tlw lxtpcr at uncc. ‘l’lie water pli;iSC, Cotltilittitlg tldlium, is nm illto ;L lxnxxlain dish (:h-M 7 x 3 cm). Sulplntrous acid (10 ltil) is n&id I_0 I, wlricli is SlIitliC!tlvigorously ffjr 130 Sec. ‘I’lic water pl~nsc is combinctl witli tllc schtiott in tllc Ixfrcclilitt tlislt. I is fi!liLlly Slli~kC_?tl for 15 See with \Virtcr (5 ml) is fXi~lKX:~t~Cl Ott tlte mid tlic water pltasc run into 11~: dish. ‘I’lic water soluth steam bat11 to dxntt one ml, (‘l’ltc t1ct~rnlitl;~tic.m may be intcrruptccl nt tllis point.) Water (5 ml) nncl l~rontocrcsol green (I drop) arc acltlcd, followccl by tlic dropwise nclclition of ;unmoniunt l~ytlro.sicl~ wit11 stirring until the dour cl1nnges ; usually about 0.7 ml is cotisuxifccl, SulIhuric acicl (I iv) is nclcled, also dropwisc, xintil the incticittor shows 11 tlCtltIXl ctr acid rcactitan. In alkaline solution tltallous ions arc osidixccl to tldlic hydrosiclc. ‘l’hc sample is now rcxly for cstractioth ~~xlvaclio?~ A spccid blat~l~ is prqxuecl at the lxgitlning of the cstraction. For tltis cstridhn hl~udc and for cacli snmplc a qjo-ml scpnrating funnel (I) and a r25-ml sclxira~itg funnel (I 1) arc rccluirccl. CItloroform (50.0 ml) is atlclccl to I. For the blank, water (20 ml) is ndclcct and for tltc sample tllc contents of the porcelain c&It. ‘Ih dish is rinsed with tlirce portions of water (dtogcthcr about 13 ml) and tlic insiclc walls arc rul~bccl with n glass rod. ‘I’llc volume of tile wutcr solution in I is now ahout 20 ml. Dithizonc misturc (40 ml) is acldccl to I, wltich is shnkctl vigorously for x min. ‘I’lic clrlorofor3n layers arc rtttl into II. The wntcr layers arc c1iscnrtlccl (arc : cyz~ticlc), ancl I is ritlsccl wit11 tlistillctl water. ‘To caclt of tltc chloroform solutions is nclclccl wash solution (25 nd), and 11 is sltnkcm for 15 sec. Tltc cldoroform layers arc rutt lmcl~ into I. (When nsing procccl~trc J3, stop at this point uric1 continue unclcr the ltcditig “l~roccditrc IS”.) ‘I’llc cldorofortn solutions arc slihx a second time for 15 see with wash solution (25 ml). A couple of ml of the cl~loroform layers arc withdrawn in or&x to remove water from tllc stopcocks. A wad of cotton is rinsed with a clilutc solution of clithiisonc in clhroform and wit11 eldorofortn and picccs are inscrtccl into tltc stems of I and pushd up against the stopcocks to scrvc as filters. A couple of ml of tltc chloroform layers are drawn off through tllc filters and cliscnrclccl. The cliloroform cstract from the lCcfcJw1ccs p. 365
VOL.
21
(Ig)5gj
DETERMIShTIOS
OF
361
1‘1
sample is read ‘I’hc absorbance
twws the cstraction blrZnk in I-CIII cells in tltc spcctt-ophotc)mctcr. at 5x0 nyc, .-I 610, is noted. Cdczrldion. Amount of thallium in the whole snmplc (or in an xliquot. SW below), in log = /tn. .4 Baa, whcrc /<,Iis obtained from ;L stanclard curve. Slamlard CZIYVC.‘I’hc standard curve is prcpnrcd by cstrnction of statttlnrcl tl~nlliunt S(JlUtiOIlS without previous combustion and separation. lTour 250-111~ scpi1r;Ltiflg funnels (I I) arc rcquircd. To 1 is iLCl
tllrec
for
I
II%.
‘rho!
~xOCCchirC
tlt~~llium-cotitaittitl~
extracts
is
ccm~hud
J,JJ’rJ:J(JJJs,\\‘I’Joss 25
g
of
Irulllnll
aS
CkSCribfX~
1lll~kX
arc wad zlcYs~s tllc csttxction
liver
wJ.rJJ wc’rc
_-_.. ..-- .._
J~~~~~J:L~~J~I~
Used
for
cncll
CStrXtiCJll.
I>li~llli
A
iLll;ll)?4iS
,rr,, .
. . -.-_
--
-__ 100
5” 5” I(10
50 50 I00 IO0 48 100 100
10
10
2
LOO 0 100
I 0 IO
205 229
100
IO
,)07
26
JO
I000
a Precipitirted Ir’c~cmtccs
fi#
A&l 365
W:LS Jwt
filtcrcd off.
IO
224
at
‘I’hC
510 lnyc.
A.
3112
DYFVERXAN
VOL.
21 (rg5g)
‘1’1~~values of .4 510 we plottccl against the amount of thallium in kq.& a straight line standard curve 1)&g obtainccl (Fig. 2). The amount of thallium, corresponding to A 610 = 1.000, is tlcnotccl by k,~. A mean value of /CA= 328 was obtained. Y/U*/JhZkS. 'I'hc Jwrl,osc of the cxtwction blank is to make the overall blank ins low and uniform as possible. ljlanlc ~letermi[laticJ~~ cm the wl~olc prttccdures have to be run frequently, and tlx blank values should Ix suhtractccl from the thallium values founcl. ‘I’lw blank clctcrminntions ;wc run on tissue samples wlGch xc free of thallium. If tissue samples ;Lrc not availalde, other organic matter such as sucrose or filter paper metals in the sample, may bc emplo~utl. ‘I’he blank values may bc due to interfering clicmicals or giuss wsscls; or it may lx caused by ar uneven distribution of free clitliixonr: in the chtorrtform phases or in oxidation products from the dithizonc, I3lenk WLILWS for llltmi~ll liver obtained by this proccclurc arc #*en in TELMC I.
‘I’lw cl~lorofw-m layers from blunlis XIX? fdntly grwn zcntl those from tldliumnbsorpt ion curves should hc positive samldcs red. Wticn red cstrwts arc obtnincd, prcp;Lrccf (cf. Fig. r) ntttl their mrwirna noted. ft is sornctimcs possihlc to dccidc from the position of tlw maximum on the nature of tltc nwtal present. hlcrcury clitliizonatc, from thut of thallium for instance, 1liU ;I pl%Lli at: 490 IlI~L, which is cluitc distinct cJitlGzon:Ltc, whew it is just below 5x0 m/l. When it is bclicvctl that tlic sample may contain more tlzan :{oo /tg of tliallium, tlx contents of xtlc lwrcdain clish xc, after nctltrdi~iltiotl, clu;mtitatisoly transferred to EL29ml volumctrit: flask uncl maclc ~tp to the ~wlltmc with wxtcr. An actcquatc amount of this solution is urltlcd to tlic separating fllnncl. W;rtcr is also atlclccl to lwing the VOhllllC of tllc ~1~lLlWLlS l~ll:LSC to 20 Id. Wiwi x0 g or less of wet tissue is wcighecl, tlic amounts of ;&Is, wstcr and otlicr chemicals usccl during comlnist ion ;~ncl s~~~~ir~itioll mrry lx reducctl by half; 250~tti1 sclxwating f7lnncls arc conw:niont for the ScpilIXti~lll, but I10 ClliLll@X+ arc necessary for the cstrnction. I+mc~hrc .I\ is follower1 to the point indicated d~ovc just after the first washing of the chlaroform cxtrztcts. The proccclurc is then as follows: ‘fhc aqueous ph;iscs arc tliscwclccl ancl I I is rinscct with crtistillccl WiktC!r. To cnch of tllc chloroform solutions arc dtlccl WiLtW (20 ml), lxomocresol green (I tlro~,) and wxtic wid (I :5; about x.0 ml). I is invcrtcd ;1, few times and the colours of the water plinscs obscrvcd. The amount of acetic acid is clictscn so iLS to give CL neutral inclicutor reaction, 1x1 ztlxxit +fi. ‘f’hc ncutrrtl green colour should persist after shaking. I is then shdccn ~$qxx-nisly for 150 sec. ‘I’lic chloroform layers we run into I I. Cliloroform (25 1111) is wldcd to 1, and water (1s ml) and ClCCtiLtc huffcr (I ml) to 11, Which is thcll slialw~ for 30 see. l’hc cllloroform layers arc cliscartlccl and the aqueous plixscs arc run into I. 11 is rinsccl with water (about 2.5 ml) which is also run into 1. “I’hc volumes of the wntcr plwxs in K will now lx about 40 ml. I I is rinscct with distilled wntcr. I is shaken for 15 xc , af;ct the chloroform laycrs are cliscarded. ‘l’hc water solutions arc washecl once qgGn by shaking for 15 see with chloroform (25 ml), :~~cl tlw chloroform layers i~rc cliscnrdcd. To cncli of the water solutions xre ndded chloroform (so.0 ml) nncl dithixonc misturc (so ml). ‘I’hcy arc then shaken vigorously for I min. 12c~eto1ccs
$4.
36.5
VOL.
21 (1959)
The dctcrmination is concluclccl w,ash solution as clcscribccl under rcncl Vcrstfs tlw cstrilction l~lallk.
Dl:TEI
OF
‘I’1
363
by two washings of tlic chlorofornl estracts with procedut-c A. “I’ltc absorption of tltc solution is then
tlw results of dctcrtnitintiotts of tlti~llilltll in liver I’PocC&lrc 11 . ‘l’al,lc I px2nts srunplcs to whicll diluted thnllium standard 1~s been ~~ltlcd. ‘I’hc thallium rccovcred after subtraction of the blml; v;~lucs is giveti in per cent of thnlliun~ added. ‘I’llC nictltod gives sliglltly tligfl rccoxxzrics of about xo_~“){,. ‘I’halliun~ scxms to lx extracted more complctcly from s,unl~lc solutions that1 from stmciard solutions. Tllc cffccts of various cations and nniotls on the yick~ of thallium ;Lrc also shown in Ti~blc 1. ‘I’hc cffccts of all known “dithizonc: nlctnls”, c.sccpt polonium, in amounts ItI most cases the added tnctals interfcrcd Up t0 50 OK- 100.111~ hVC bCCt1 tC?StCd. little or not at all, but four metals \vcrc found to interfcrc seriously with the thallium anal}-sis; thcsc arc mercury in iWIO\ttIts csccoding about f Jllg, and c~~dmium. bismuth and indium when ~norc thiltI alqmximatcly IO mg were prcscnt. In practice with l~iological simq~lcs, cadmium, bismuth or indiurn contcnts cscccding IO mg seldom occur. Mcrcary coutcnts cscccding I rug in 25 g of kiclncy occur in casts of lethal mercury poisoning. l-lalogcn, thiosulpl~atc and thiocyanatc ions had Iittle effect on the detcrllli~latiotl. Proccdwc
Table
I3. The msults of determinations according to procedure B arc shown in II. The yields were a little lower than for procedure A, being around or slightly
j Referewes
$. 365
VoI.. 21 (1959)
364
___.__._. __ _. __ ___.._ __. _. .._ .._-. ___._._
______.____._ - _.__. . ___. - -. ..- - -.-._..-.- - .-..- -----_-
/I llild
I.irvr
______.
‘1’1 I’#
__._
iwr
. __--__-...-.
8
Ii
IO0 200
1:
3”O 200
I Ig”
100
1:
(:d’*
IO0
1:
200
Cd”
1:
200
IZiIII
‘200
A ; 10 pg
ill
rcason;Ll>lc ‘I‘lw
influcncc that
samples
could
tlic
four
Jncrcury ;lffC!ct
intcrfcrccl
III&
c
a SllliL.llW tldliuJn
Of of
Clid IlOt
nlg)
(50
liver
tldlium
-.--_-_.
for
less
0
09
95.5
303 ‘137
0
I0 I
0
I 18.5
31x
0
IO<)
1 1 ‘J
0
1W.5
contctlt
--..
tlml
ClWdit:~tivcly
_-_
pg,
_....._ _.
tlic
__ ._._____
yicltls
samples,
liver
tlroppcd
made it pas-
IJ tllilll wit11 proccdurc
wit11 proccclurc
1x2 ;~Ii:tlysccl,
101.5
0
_ ._ _._.__-.
50
tliffcrcnt
txvo
87.5
rid
cl~l;~~~tit;~tivCI~~,
with
acclmLcy.
cspccinlly (100
luwcst
..--.
. .
80
0
CJ
203
I (JO
. ..-....-_ -.--..---_._
l~larlli VillUCS,
low
siblc to dctwniitw
IO0
1111”
lx~low x00’%,. At tlx ‘I’llc
SO
o
I ‘J 1
90
.--..____- ..__......._-
go-()0,x,.
-_--____.___
35
1:
...^_. -_--
HKOUCry ‘!:I
Iilunlk
._----___-__..-
_. .-...
,I0
ti
to
.
^--_-_._
Jtr:
f~‘orold
or<
IO
G G
__-.
?‘hullirrm,
metals
(‘l’ablc tllc
only
11)
wl~icli
; it
interfcrcd
\VilS foulld
C\~tWJllilmtiOll
tlliLt
in
procedure
mercury
\\*IlC!TTiE+ lIiSJllUtl1
A
(100 (100
Jllg)
\ViLS stiiclicd,
Jng)
utld
ilIld
indium
C;ldJllil.lJll
slij$tly.
‘L’v*o ViI.t’i~tilJIlS of n Inctlird for tllc dctcrlIliIlirtioI1 of inicrogrrim nmounts of LllillliIllll in I,iological trinLcri;rl lmvc 11ccn workctl uut. After wet ctJIilbIlSLiOl1 antI sclxw;LLioiI of thalliutn from most intcrfcring sir~l~stnnccs I>y cxLr;icLiml of Lh;Illic chloritlc wit11 ctlicr, the Inct;il is cstinmtctl absorplitmicLric;illy :Is its tliLlIi~oIlirtc, the yicltl Lwing slightly ~rc;itcr tlI;in Llicorcticd (proccdIIrc A). 111tlIc prcscncc of Iiicrcury (> I Illfi), cxl1i~iIIIIi, I~isnIiILlI iLll 10 rng) liigli results wcrc IlliOYlII~~I1ilt~ iitltl LliiwyiIi:rtc ions tlitl not intcrlcrc. \Vitli tlic ol.~Lainctl. OLlIcr 1llcL~rls, IliIlO~Oil, hllgcr
Slightly up
tu
50
M
IO
146
~~rMxc~llrc
riig. Of
For
13, ScriUllS
practical
~~l~~~~illlll
ill
25
illtcrhXI!llcc
purlmscs
lmxxilurc
g
CCJlllC\
Of
liVCl*
IIC
W'aS
1% can
IlOL
cIiC~JUIiLCrcd
IJC coiisidcrcd
fronl slzcific
tilly for
lllct:ll
tkdliuni.
in
anl~JIIlltS
As
little
t~~Lcrlllill~d.
1Xx1x wiriantcs sont Iwolwsbcs pmr Ic tlosngc tlii Llinlliuni clans tics sulwtnnccs I~iologiqucs. Aptis llliIlbKLliSiLtio1~ ct cxtrrrctioii, Ic LlialliI11n cst rlosd ~i~surl~tiom6Lrii~iIcIiicIit sous forrnc dc diLliizon:itc. l,‘IIn dc ccs pruc&lA csL 1iic:ins 1.ill)idc: clIIc I’ilIlLIX!; 1lliliS il pout Strc Consid& pratiqucnicrit
coninic
spkifiilucO
Es wcrilcn zwci Vnrirrntcn ciiicr ;\IctlIodc lmxliricbcn 2tIr 13cstiInrnung von Thnlliun~ in biologischcn~ Blatcrial. Nrrch ZcrstBrung tlcr orgiwiscllcn Substunz wircl tlas Tlrallidn~ ;Ils Chloricl cxtraDie cinc Vnriantc bcnOtigt ctwas nichr lsicrt und als IXtliitonnt nbsorptiomctriscl~ bcstinimt. Zcitaufwand, kiln11 abcr nls spcxifisch I>uLr;~cllLct wcrdcn. 12e/cvcirces
p.
365
VOL.
21 (xgsg)
DETISHMINATION
01’
‘I’]
3%
The basic quantities measured in clcctroanalyticnl cllcmislry arc: current, potential, of these quantities ant1 time. Xlcasurcnlcnt or rccorcling of various combinations ~CCOlllltS
for
JllOSt
ClCCtr(~atl:~lytiCil1
1llCthOtk:
at constant l)otcntial, (c.6. polarograCurrent vs. potclltii~l, (a) voltanunctry at continuously cllanging l)otcntial, (c) cLJrrcnt-electrotlc phy), (b) voltammetq potential curves with nlncro-clccttotlcs. 2. Potential ‘us. time, (a) chronol’fJtcntiomctry, (b) potcntiomctric titration curves, involving coulornctric gcncration or constant ntlclition of titrant. is. Current 13. time. (a) clironoampcromctry, (b) ampcromctric titration curves, coulomctric generation or constant atldition of titrant. Rccorcling of current or potential US. time is generaIl>* easily performcrl witli galvanornetcr or “colltilluous-balance” strip chart rccordcrs. ‘I’hc rccortling of current vs. potential, however, involves synchronizing the chart clrivc of the rccordcr with the is being polarizing unit drive. Since cell voltage, rather than electrode potential, rccordecl, the polarization curve inevitably includes the ii\’ drop of the circuit. Although this il\’ tlrop gcncrally does not cause serious error in the measurctl potentials when the cell rcsistancc and current are small (q. polarography), attempts to record large currents (up to KOOmA) VS. potential, for example for use in predicting current efficicncics in coulometric titrations, arc doomed to failure. The direct recording of current-potential curves, as pointed out by JANCANE’, could recording the c.m.f. be accomplished with an X-Y recorder (or “function plotter”), between the working electrode and a reference electrode on one axis, and the current I.
R_efercnces
fi. 369
tn
m
zi c:
9
i*’ h
l-i
A.
358
VOI,. 21 (ICJj5))
I~YFVEI
AS 11 1<0ss0*l-l7’ “. ‘I’lwir data also suggcstctl, that l~ytlrocldoric acid wry pcobal~ly could Ix rcplncctl II) ;L sulphric acid solution containing I .1f sodium cliloriclc. Rcestraction of tldlous cl&x-itlc into water is Cxsily xcoml~lislwcl. In tllc final cxtruction step tlitlrizonc is aclclccl in wnmonincal solution in or&r to rccluco intcrfcrcncc from cllloroform-soltIhlc impurities prcscnt in clitllizone. ‘l’ldlium ditllizonutc and some csccss free clitllizonc arc c_stractctl into chlorr~forrn. Most of tllc free dithizonc is rcnwvccl by two wasllings wit11 8 dilute ammoniacal solution; the mimnt rcrnuinirlg in tlw cliloroforrn phw clots not il.ffC!Ct tile tlcterrninntion of tll3lliIlJll. ‘1’1lC (3)rltcnt Of tll;llliUJll iS Ci~lcllliLtC~.l fro111 tllc iLl~S;orb~LllC~ il.t 510 Jll//.. AbSoI’ptiOll C111’\‘CS for ditllizom! ilnd t1liL11illJll ditlliZOlXit,c iLW StlOWll in I;ig. I.
550
600 ny
‘I’llc clctcrmination of tlliLl1illlll, iLS outlined il.lIOVC! (prou3lurc A), is sufficiently specific for most purposes illId iS lX~~~~lllll~tldC
Analyticd Statwl.
rite,
rcxrycnts antI Khss-clistillctl water arc risccl tllrouyl~out, Cxccpt wllcrc oLlwrwisc should bc csclutlctl tluring all work wit11 solutions cont;rininy: cliloriiic.lry~~ocl~l~~tlitliizonc illltl tliiillilliil tlitliizoiliitc. Coiwi?iLctit clcnnlincss is rnosl iiiiprtant in this type r~f Ikryli&t
work.
DigcslioJr
.%/2~~b’fdiQ’
fl~/Jtir’fllffs, JJdS,
/Ill,
:uxortling Gikoll
lllldt2\,
to
I
as
50”
, 250
125
;Lll(l
311.
0111~
in
il
filiE?i
SC~XlGltill~
fllllllClS.
RC~CWJUCS p, 3G5
chl
JJiJlg
O/ ,$USSfUlC,T.
iisc the tligcstim
pwvicms
Cotllllllllliciltiol~~~.
ilrc 1lSctl for ;rppnmtus IS lmilcrl
stcqqwrs
fI:Wl
with nitric ilCitl, am.1 lxfurc the iicst irll;LlySiS Imilctl with watci . Scpnriiting fuiincls, including grwnd surfaces, mltl other glirssw:rrc iwc clcanccl witli raw, pWfCril,l)ly cliloriiic-cont;rinill~, hytlrocllloric l citl and tlicn rinsctl wry Cil,rCfUllY with warm wrtcr nntl tlistillcrl wnlcr. I’iKJl/iJfJJJ SfflJJdflJ~~. I 1116 ‘l’l/llll. ‘l’lli\llOUS nitrate (65 1 .7 iii&) is tlissolvcrl in water irlld tnadc up to 500 ml.
IllId
AfLcr
dcscril~ctl
.
360
A. DYFVEI
VOL.
21 (Xcf~cj)
Flask anti filter are waslrcd wittl 50 ml of water (altogetller 100 ml of water arc ~ltlccl) a~~1 socliutn chloride (0.5 g) is adclccl and clissolvcd. I-Iypocltloritc solution (:! ml) is aclclccl in portions with swirling, followvcxl after mising, by cthcr (125 ml). A roam1 cylirttlor is put lxncatll onch scprrrating funnol to catch any drops escaping. ‘l’ltc prcssurc stlould always lx rchsctl bcforc shaking when ether is present. The fxtnrtol is t l~cn shaken vigcxrtusly for txo min. A moistcnccl potassium iodide-starch lxil)cr shows whit tlic val)our pl~se contains im cxccss of chlorine. After a minute tllc wa.tcr pliasc is run into 1 I. Clrlorinc solution (io ml) is A_Ictl to tllc cthcr in I, wliicll is sIdxtt for 15 sec. ‘1’1~ \ViltCX l>li;Lsc is coml~inetl wit11 the first water pllasc in I I. I, containing an ctllcr solution wit11 most of tltc thllium, is stqqxccl. (its stem ant1 tltc cylinclcr lxacuth it arc rinsd). I-fyIxxliIoritc solutiotl (2 ml) trncl cthct- (05 ~1) are acltlecl to 11, whic11 is sliukcn \~ig0tYNlSly for 1 mill. ‘I’hC W1t.W ])haSC k C~kXlrCk!C~. ChkJrim2 S(Jhhll (20 ml) k XkkCl md I I is shalicn for x.5 sec. ‘TIE water pltasc is again discnrclcd ant1 tllc etlxrr ])llilSC: cotnl~ittetl wit11 the first ctlicr whition in I. I I is rhsccl with iI_ small amount of ctltcr. ‘l’lic collectccl other cstracts are s1x~lccn vigorously for x tnin with sttll~l~~sr~Ils acid (15 ml). A ttdstctxd potassium iodictc-starch pupr, maclc blue dx0~c ttic chlnrittc solution, is hclcl in the vapour pltusc of I. Sulplntr cliosidc gas sl~oulcl lx present ~llost of tllc in csccss and l~lcacl~ tlw lxtpcr at uncc. ‘l’lie water pli;iSC, Cotltilittitlg tldlium, is nm illto ;L lxnxxlain dish (:h-M 7 x 3 cm). Sulplntrous acid (10 ltil) is n&id I_0 I, wlricli is SlIitliC!tlvigorously ffjr 130 Sec. ‘I’lic water pl~nsc is combinctl witli tllc schtiott in tllc Ixfrcclilitt tlislt. I is fi!liLlly Slli~kC_?tl for 15 See with \Virtcr (5 ml) is fXi~lKX:~t~Cl Ott tlte mid tlic water pltasc run into 11~: dish. ‘I’lic water soluth steam bat11 to dxntt one ml, (‘l’ltc t1ct~rnlitl;~tic.m may be intcrruptccl nt tllis point.) Water (5 ml) nncl l~rontocrcsol green (I drop) arc acltlcd, followccl by tlic dropwise nclclition of ;unmoniunt l~ytlro.sicl~ wit11 stirring until the dour cl1nnges ; usually about 0.7 ml is cotisuxifccl, SulIhuric acicl (I iv) is nclcled, also dropwisc, xintil the incticittor shows 11 tlCtltIXl ctr acid rcactitan. In alkaline solution tltallous ions arc osidixccl to tldlic hydrosiclc. ‘l’hc sample is now rcxly for cstractioth ~~xlvaclio?~ A spccid blat~l~ is prqxuecl at the lxgitlning of the cstraction. For tltis cstridhn hl~udc and for cacli snmplc a qjo-ml scpnrating funnel (I) and a r25-ml sclxira~itg funnel (I 1) arc rccluirccl. CItloroform (50.0 ml) is atlclccl to I. For the blank, water (20 ml) is ndclcct and for tltc sample tllc contents of the porcelain c&It. ‘Ih dish is rinsed with tlirce portions of water (dtogcthcr about 13 ml) and tlic insiclc walls arc rul~bccl with n glass rod. ‘I’llc volume of tile wutcr solution in I is now ahout 20 ml. Dithizonc misturc (40 ml) is acldccl to I, wltich is shnkctl vigorously for x min. ‘I’lic clrlorofor3n layers arc rtttl into II. The wntcr layers arc c1iscnrtlccl (arc : cyz~ticlc), ancl I is ritlsccl wit11 tlistillctl water. ‘To caclt of tltc chloroform solutions is nclclccl wash solution (25 nd), and 11 is sltnkcm for 15 sec. Tltc cldoroform layers arc rutt lmcl~ into I. (When nsing procccl~trc J3, stop at this point uric1 continue unclcr the ltcditig “l~roccditrc IS”.) ‘I’llc cldorofortn solutions arc slihx a second time for 15 see with wash solution (25 ml). A couple of ml of the cl~loroform layers arc withdrawn in or&x to remove water from tllc stopcocks. A wad of cotton is rinsed with a clilutc solution of clithiisonc in clhroform and wit11 eldorofortn and picccs are inscrtccl into tltc stems of I and pushd up against the stopcocks to scrvc as filters. A couple of ml of tltc chloroform layers are drawn off through tllc filters and cliscnrclccl. The cliloroform cstract from the lCcfcJw1ccs p. 365
VOL.
21
(Ig)5gj
DETERMIShTIOS
OF
361
1‘1
sample is read ‘I’hc absorbance
twws the cstraction blrZnk in I-CIII cells in tltc spcctt-ophotc)mctcr. at 5x0 nyc, .-I 610, is noted. Cdczrldion. Amount of thallium in the whole snmplc (or in an xliquot. SW below), in log = /tn. .4 Baa, whcrc /<,Iis obtained from ;L stanclard curve. Slamlard CZIYVC.‘I’hc standard curve is prcpnrcd by cstrnction of statttlnrcl tl~nlliunt S(JlUtiOIlS without previous combustion and separation. lTour 250-111~ scpi1r;Ltiflg funnels (I I) arc rcquircd. To 1 is iLCl
tllrec
for
I
II%.
‘rho!
~xOCCchirC
tlt~~llium-cotitaittitl~
extracts
is
ccm~hud
J,JJ’rJ:J(JJJs,\\‘I’Joss 25
g
of
Irulllnll
aS
CkSCribfX~
1lll~kX
arc wad zlcYs~s tllc csttxction
liver
wJ.rJJ wc’rc
_-_.. ..-- .._
J~~~~~J:L~~J~I~
Used
for
cncll
CStrXtiCJll.
I>li~llli
A
iLll;ll)?4iS
,rr,, .
. . -.-_
--
-__ 100
5” 5” I(10
50 50 I00 IO0 48 100 100
10
10
2
LOO 0 100
I 0 IO
205 229
100
IO
,)07
26
JO
I000
a Precipitirted Ir’c~cmtccs
fi#
A&l 365
W:LS Jwt
filtcrcd off.
IO
224
at
‘I’hC
510 lnyc.
A.
3112
DYFVERXAN
VOL.
21 (rg5g)
‘1’1~~values of .4 510 we plottccl against the amount of thallium in kq.& a straight line standard curve 1)&g obtainccl (Fig. 2). The amount of thallium, corresponding to A 610 = 1.000, is tlcnotccl by k,~. A mean value of /CA= 328 was obtained. Y/U*/JhZkS. 'I'hc Jwrl,osc of the cxtwction blank is to make the overall blank ins low and uniform as possible. ljlanlc ~letermi[laticJ~~ cm the wl~olc prttccdures have to be run frequently, and tlx blank values should Ix suhtractccl from the thallium values founcl. ‘I’lw blank clctcrminntions ;wc run on tissue samples wlGch xc free of thallium. If tissue samples ;Lrc not availalde, other organic matter such as sucrose or filter paper metals in the sample, may bc emplo~utl. ‘I’he blank values may bc due to interfering clicmicals or giuss wsscls; or it may lx caused by ar uneven distribution of free clitliixonr: in the chtorrtform phases or in oxidation products from the dithizonc, I3lenk WLILWS for llltmi~ll liver obtained by this proccclurc arc #*en in TELMC I.
‘I’lw cl~lorofw-m layers from blunlis XIX? fdntly grwn zcntl those from tldliumnbsorpt ion curves should hc positive samldcs red. Wticn red cstrwts arc obtnincd, prcp;Lrccf (cf. Fig. r) ntttl their mrwirna noted. ft is sornctimcs possihlc to dccidc from the position of tlw maximum on the nature of tltc nwtal present. hlcrcury clitliizonatc, from thut of thallium for instance, 1liU ;I pl%Lli at: 490 IlI~L, which is cluitc distinct cJitlGzon:Ltc, whew it is just below 5x0 m/l. When it is bclicvctl that tlic sample may contain more tlzan :{oo /tg of tliallium, tlx contents of xtlc lwrcdain clish xc, after nctltrdi~iltiotl, clu;mtitatisoly transferred to EL29ml volumctrit: flask uncl maclc ~tp to the ~wlltmc with wxtcr. An actcquatc amount of this solution is urltlcd to tlic separating fllnncl. W;rtcr is also atlclccl to lwing the VOhllllC of tllc ~1~lLlWLlS l~ll:LSC to 20 Id. Wiwi x0 g or less of wet tissue is wcighecl, tlic amounts of ;&Is, wstcr and otlicr chemicals usccl during comlnist ion ;~ncl s~~~~ir~itioll mrry lx reducctl by half; 250~tti1 sclxwating f7lnncls arc conw:niont for the ScpilIXti~lll, but I10 ClliLll@X+ arc necessary for the cstrnction. I+mc~hrc .I\ is follower1 to the point indicated d~ovc just after the first washing of the chlaroform cxtrztcts. The proccclurc is then as follows: ‘fhc aqueous ph;iscs arc tliscwclccl ancl I I is rinscct with crtistillccl WiktC!r. To cnch of tllc chloroform solutions arc dtlccl WiLtW (20 ml), lxomocresol green (I tlro~,) and wxtic wid (I :5; about x.0 ml). I is invcrtcd ;1, few times and the colours of the water plinscs obscrvcd. The amount of acetic acid is clictscn so iLS to give CL neutral inclicutor reaction, 1x1 ztlxxit +fi. ‘f’hc ncutrrtl green colour should persist after shaking. I is then shdccn ~$qxx-nisly for 150 sec. ‘I’lic chloroform layers we run into I I. Cliloroform (25 1111) is wldcd to 1, and water (1s ml) and ClCCtiLtc huffcr (I ml) to 11, Which is thcll slialw~ for 30 see. l’hc cllloroform layers arc cliscartlccl and the aqueous plixscs arc run into I. 11 is rinsccl with water (about 2.5 ml) which is also run into 1. “I’hc volumes of the wntcr plwxs in K will now lx about 40 ml. I I is rinscct with distilled wntcr. I is shaken for 15 xc , af;ct the chloroform laycrs are cliscarded. ‘l’hc water solutions arc washecl once qgGn by shaking for 15 see with chloroform (25 ml), :~~cl tlw chloroform layers i~rc cliscnrdcd. To cncli of the water solutions xre ndded chloroform (so.0 ml) nncl dithixonc misturc (so ml). ‘I’hcy arc then shaken vigorously for I min. 12c~eto1ccs
$4.
36.5
VOL.
21 (1959)
The dctcrmination is concluclccl w,ash solution as clcscribccl under rcncl Vcrstfs tlw cstrilction l~lallk.
Dl:TEI
OF
‘I’1
363
by two washings of tlic chlorofornl estracts with procedut-c A. “I’ltc absorption of tltc solution is then
tlw results of dctcrtnitintiotts of tlti~llilltll in liver I’PocC&lrc 11 . ‘l’al,lc I px2nts srunplcs to whicll diluted thnllium standard 1~s been ~~ltlcd. ‘I’hc thallium rccovcred after subtraction of the blml; v;~lucs is giveti in per cent of thnlliun~ added. ‘I’llC nictltod gives sliglltly tligfl rccoxxzrics of about xo_~“){,. ‘I’halliun~ scxms to lx extracted more complctcly from s,unl~lc solutions that1 from stmciard solutions. Tllc cffccts of various cations and nniotls on the yick~ of thallium ;Lrc also shown in Ti~blc 1. ‘I’hc cffccts of all known “dithizonc: nlctnls”, c.sccpt polonium, in amounts ItI most cases the added tnctals interfcrcd Up t0 50 OK- 100.111~ hVC bCCt1 tC?StCd. little or not at all, but four metals \vcrc found to interfcrc seriously with the thallium anal}-sis; thcsc arc mercury in iWIO\ttIts csccoding about f Jllg, and c~~dmium. bismuth and indium when ~norc thiltI alqmximatcly IO mg were prcscnt. In practice with l~iological simq~lcs, cadmium, bismuth or indiurn contcnts cscccding IO mg seldom occur. Mcrcary coutcnts cscccding I rug in 25 g of kiclncy occur in casts of lethal mercury poisoning. l-lalogcn, thiosulpl~atc and thiocyanatc ions had Iittle effect on the detcrllli~latiotl. Proccdwc
Table
I3. The msults of determinations according to procedure B arc shown in II. The yields were a little lower than for procedure A, being around or slightly
j Referewes
$. 365
VoI.. 21 (1959)
364
___.__._. __ _. __ ___.._ __. _. .._ .._-. ___._._
______.____._ - _.__. . ___. - -. ..- - -.-._..-.- - .-..- -----_-
/I llild
I.irvr
______.
‘1’1 I’#
__._
iwr
. __--__-...-.
8
Ii
IO0 200
1:
3”O 200
I Ig”
100
1:
(:d’*
IO0
1:
200
Cd”
1:
200
IZiIII
‘200
A ; 10 pg
ill
rcason;Ll>lc ‘I‘lw
influcncc that
samples
could
tlic
four
Jncrcury ;lffC!ct
intcrfcrccl
III&
c
a SllliL.llW tldliuJn
Of of
Clid IlOt
nlg)
(50
liver
tldlium
-.--_-_.
for
less
0
09
95.5
303 ‘137
0
I0 I
0
I 18.5
31x
0
IO<)
1 1 ‘J
0
1W.5
contctlt
--..
tlml
ClWdit:~tivcly
_-_
pg,
_....._ _.
tlic
__ ._._____
yicltls
samples,
liver
tlroppcd
made it pas-
IJ tllilll wit11 proccdurc
wit11 proccclurc
1x2 ;~Ii:tlysccl,
101.5
0
_ ._ _._.__-.
50
tliffcrcnt
txvo
87.5
rid
cl~l;~~~tit;~tivCI~~,
with
acclmLcy.
cspccinlly (100
luwcst
..--.
. .
80
0
CJ
203
I (JO
. ..-....-_ -.--..---_._
l~larlli VillUCS,
low
siblc to dctwniitw
IO0
1111”
lx~low x00’%,. At tlx ‘I’llc
SO
o
I ‘J 1
90
.--..____- ..__......._-
go-()0,x,.
-_--____.___
35
1:
...^_. -_--
HKOUCry ‘!:I
Iilunlk
._----___-__..-
_. .-...
,I0
ti
to
.
^--_-_._
Jtr:
f~‘orold
or<
IO
G G
__-.
?‘hullirrm,
metals
(‘l’ablc tllc
only
11)
wl~icli
; it
interfcrcd
\VilS foulld
C\~tWJllilmtiOll
tlliLt
in
procedure
mercury
\\*IlC!TTiE+ lIiSJllUtl1
A
(100 (100
Jllg)
\ViLS stiiclicd,
Jng)
utld
ilIld
indium
C;ldJllil.lJll
slij$tly.
‘L’v*o ViI.t’i~tilJIlS of n Inctlird for tllc dctcrlIliIlirtioI1 of inicrogrrim nmounts of LllillliIllll in I,iological trinLcri;rl lmvc 11ccn workctl uut. After wet ctJIilbIlSLiOl1 antI sclxw;LLioiI of thalliutn from most intcrfcring sir~l~stnnccs I>y cxLr;icLiml of Lh;Illic chloritlc wit11 ctlicr, the Inct;il is cstinmtctl absorplitmicLric;illy :Is its tliLlIi~oIlirtc, the yicltl Lwing slightly ~rc;itcr tlI;in Llicorcticd (proccdIIrc A). 111tlIc prcscncc of Iiicrcury (> I Illfi), cxl1i~iIIIIi, I~isnIiILlI iLll
Slightly up
tu
50
M
IO
146
~~rMxc~llrc
riig. Of
For
13, ScriUllS
practical
~~l~~~~illlll
ill
25
illtcrhXI!llcc
purlmscs
lmxxilurc
g
CCJlllC\
Of
liVCl*
IIC
W'aS
1% can
IlOL
cIiC~JUIiLCrcd
IJC coiisidcrcd
fronl slzcific
tilly for
lllct:ll
tkdliuni.
in
anl~JIIlltS
As
little
t~~Lcrlllill~d.
1Xx1x wiriantcs sont Iwolwsbcs pmr Ic tlosngc tlii Llinlliuni clans tics sulwtnnccs I~iologiqucs. Aptis llliIlbKLliSiLtio1~ ct cxtrrrctioii, Ic LlialliI11n cst rlosd ~i~surl~tiom6Lrii~iIcIiicIit sous forrnc dc diLliizon:itc. l,‘IIn dc ccs pruc&lA csL 1iic:ins 1.ill)idc: clIIc I’ilIlLIX!; 1lliliS il pout Strc Consid& pratiqucnicrit
coninic
spkifiilucO
Es wcrilcn zwci Vnrirrntcn ciiicr ;\IctlIodc lmxliricbcn 2tIr 13cstiInrnung von Thnlliun~ in biologischcn~ Blatcrial. Nrrch ZcrstBrung tlcr orgiwiscllcn Substunz wircl tlas Tlrallidn~ ;Ils Chloricl cxtraDie cinc Vnriantc bcnOtigt ctwas nichr lsicrt und als IXtliitonnt nbsorptiomctriscl~ bcstinimt. Zcitaufwand, kiln11 abcr nls spcxifisch I>uLr;~cllLct wcrdcn. 12e/cvcirces
p.
365
VOL.
21 (xgsg)
DETISHMINATION
01’
‘I’]
3%
The basic quantities measured in clcctroanalyticnl cllcmislry arc: current, potential, of these quantities ant1 time. Xlcasurcnlcnt or rccorcling of various combinations ~CCOlllltS
for
JllOSt
ClCCtr(~atl:~lytiCil1
1llCthOtk:
at constant l)otcntial, (c.6. polarograCurrent vs. potclltii~l, (a) voltanunctry at continuously cllanging l)otcntial, (c) cLJrrcnt-electrotlc phy), (b) voltammetq potential curves with nlncro-clccttotlcs. 2. Potential ‘us. time, (a) chronol’fJtcntiomctry, (b) potcntiomctric titration curves, involving coulornctric gcncration or constant ntlclition of titrant. is. Current 13. time. (a) clironoampcromctry, (b) ampcromctric titration curves, coulomctric generation or constant atldition of titrant. Rccorcling of current or potential US. time is generaIl>* easily performcrl witli galvanornetcr or “colltilluous-balance” strip chart rccordcrs. ‘I’hc rccortling of current vs. potential, however, involves synchronizing the chart clrivc of the rccordcr with the is being polarizing unit drive. Since cell voltage, rather than electrode potential, rccordecl, the polarization curve inevitably includes the ii\’ drop of the circuit. Although this il\’ tlrop gcncrally does not cause serious error in the measurctl potentials when the cell rcsistancc and current are small (q. polarography), attempts to record large currents (up to KOOmA) VS. potential, for example for use in predicting current efficicncics in coulometric titrations, arc doomed to failure. The direct recording of current-potential curves, as pointed out by JANCANE’, could recording the c.m.f. be accomplished with an X-Y recorder (or “function plotter”), between the working electrode and a reference electrode on one axis, and the current I.
R_efercnces
fi. 369