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CCJLCRH‘AETREC DETERMINATICN
OF CADMEUM
3H” MEANS OF DETHIZONE

Thesis for the Degree 01 M. S.
MlCHiGAN STATE, CCLLEGE
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m GOLOWIO DETENIHATION
0? mm
BY mm 01’ mmzon

by
Georg. Illhra ”trons

A mm
Bubnittod to tho Gradusto School at Michigan
Stat. 0011030 or Agriculturo and Appliod
Scion“ in prtiu fulfillment of the
maimentc for the decree 0:

MASTER OF 801m}!

Department of Chemistry

1 939

amyvflflr'" " ""‘
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WOW!
2h. tritor with“ to an this opportunity to ox-
” hi. oinoorut appreciation to Ir. 3. Laminar
for hit our helpful tugs-ouch: uni oritioim mioh

have no. pouiblo tho work which oppooro in thin pupa.

126?18

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MIDDIBTION
nmmmw. Simon

immanen-

monma. mm, 33403933
momma m M
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(1:0ng

1‘

INTEDUCTION

In recent yeere the inoreeeing importance of the de-
tection of trece metele end the eetineticn of their enonnte
hee denuded e eeneitive method for their determineticno he
control of leed left upon fruit ee eprey recidne end the de-
tection of trece netele preeent in cree, ellcye, etc.. ee
impuritiee he etinnleted reeeerch into the me of dithiscne
(diphenyl thiccerhucne) ee enelyticel reeaent in ench pro-
cednree.

Beeldee lead, zinc hee perhepe received the meet etten-
ticn cc to the poeeihilitiee of tin dithiscne nethcde in
trece detection.

lhe eulyeie of trecee of cocaine in one of the eppli-
cetione vhioh. elthcnah the pceeibilitiee hove been reclined.
hee no little done tcnrd ite edvenoelent. fhe field of
reeeerch in admin then ie etlll Open. It will be the ct-
tonpt of thie peper to introduce nee proceduree in the di-
thiecne methods for ocdniun end. if pceeible. to improve
upon any clreedy exietinc.

Inch my be learned of velne to the detection of ced-

niun from c perneel of the literetnre for leed, cine. end

the other heavy metele. Since the cunt of cork done in

(1)

connection with cedninn he been cull, thie will be
neceuery, for it is beyond the eccpe of thie peper to

give e complete digeet of ell exietinc literature.

(2)

HIB'IORIOAL SKIN!

In Germ in 1883 Dell Piecher (l) in hie work
upon the prcpertiee end reecticne cf phewl hydreeine
'firet cene upen dithiecne. it thie tine he recomieed
the feet tint it found e colored complex with line.
It m neerly fifty yeere leter, however, thet enyone
thoualt cf the pceeibility of the use of dithiecne ee .
en enelyticel reemto

Hell-ht Fiecher. elec working in Gernny. firet
etudied the pceeibilitiee cf the dithieone compleeee
in the qmlitetive detection of w heevy mtele,
encng which were lend. copper. gold, eilver. mercury,
end oedniun. mic wee in 192‘. A yeer leter he pub-
liched hie findinp in 'iee. Veroff. Sienna-Kenn. (2)
Very little intereet wee ercueed however end except
for e few ecettered pepere by tieoher hineelf, end e
for euthcre in Melend. little no published of velue
upon the nee of dithiecne. in 1984 in Angew. Ohenie
(a) Piecher publiehed encther peper upon the nee of
dithiecne in enelyeie, both in quelitetive end quen-
titetive nicrcohemietry. Since tbt time more then
fifty pepere heve been publiehed decline with the uee

of dithieone in enelyeie. root of which heve deelt
(3)

with.leediend sheen

In the tine eince 1935 eeverel nethcde heve been
developed for'the uee of dithieone. Direct end indi-
rect titreticn nethcde heve been developed, ee well ee
leverel colorimetric proceduree which.will be die-
cueeed leter. Due to the inlolubility of the dithieene
complex“ in nter. en etteqpt wee nude to develOp e
grevimetric procedure. However, it wee found thet et
tempereturee cufficiently high.tc remove the enter ne-
chenieelly held, the dithiecne complexee begen to de-
conpoee neceeeiteting finel weighing en the oxide,
eulfidb. or eulfete. Under certein condition! nix:
turee of eny two or ell of theee emit occur. Since
thie wee true end mince the edventeee of the hid; nel-
eculer weight of the dithiecnete wee lcet, the ettenpt
wee diecerded.

A complete bibliogrephy of the work with dithi.
none up to 1957 wee publilhed in.Aneewendte Gheeie (e)
by Piecher elcng with the methane then in nee, A per-
tiel liet including pepere publiehed eince 1937 my be

found et the end of thie report.

(4)

 

 

THEORET 10.“.

All the dithiecne methode depend upon the feet
tint certein of the heevy netele fore colcnd con-
plenee with dithiecne. niece oomplexee ere inecluble
in weter, but eoluble in chloroforn end other arsenic
eclvente. Piecher in hie erticle in Angewendte Ohenie

(a) ave the following form enietins for dithieoneg

incl Kete
U Eel-l5- 9H5-
/ :1. ”=0
H—S—C\ sag/
\M‘?~H \pyu-n’
/ I

end poetuleted the following poeeibilitiee for the

heevy motel oomplexee:

m1 9 w; ’0: Se 14‘;
+ /’U = U / “. H
M 5“c.\\ 5.0+ C\\-5—x;o
M—A) “*1?
l
KOtO
/ -
S: C ’7‘"
\M— A)
/ /
44- (6”

lith the divelent netele the come linkege tekee plece,
but enother molecule of dithiecne in need. Of the
three velent metele reecting only the keto fore hee
been found to exiet et thie writing. lith theee the
bend type ie the me. but the formule tehee three
moleculee of dithiecne.

According to Pincher (8) the ketc fcme ere gen-
erelly exietent in neutrel or ecid ecluticn with e few
exceptione of which cedeiun ie one, while the encl fou
exiete in beeic eclut ion.

nor the cedmium complex the following form hee
been chown to exiet in neutrel tc etrcngly elkeline

C’ ,
eolutione: C 6 5/;- .‘ "Le

’ 1"—
/’U‘:/\/\ ,"N N\ _
C ‘00! (3‘5

I
M. {F}; can“;
hie hee been oontrected for convenience to 06.132. i’he
exietence of en emcl complex of cadmium hee on yet not
been proved.

According to cliffcrd end Iichmenn (5) the moot
complete oomplexing of oedmium tekee plece ebcve the
pH velue of twelve, with the complex firet forming et
e pH of ereund nine.

(6)

Fieoher in hie work found that en end concentreticn of
five per cent ecdiun hydroxide ave the beet reeulte.
lt no noticed by thie obeerver in ccrrcbcreticn cf
theee workere thet the extrecticn cf cedniue with e
twenty-five per cent exceee of dithiecne begen et e pl!
between eight end nine end wee eoet complete ebcve e
velue of twelve. From thie point to e concentreticn
of eppreximetely ten per cent ecdium hydroxide there
eeeeed to be no eppreoieble difference in the coloring
of the dithiecne-chlorofcrm extrect. However, ebcve
thie ccnccntreticn the colcre eain eeemd to decreeee
in inteneity.

Thie method ie by no meene epeoific for cedmiue.
Fischer end Loopcldi (6) cleie, however, thet only the
following netele interfere: copper. eilver. aid,
mercury, pellediun. nickel, cobelt, end zinc in lerge
emounte. Alec eny ion precipiteting in the elkeline
eolution will ceuee incomplete extrecticn cf cedniue.
Such lone ere phcephetc, ferric, chronic. eluminiun,
etencue, etc. Sendell in e recent peper (7) hee eeid
tint menaneee elec interferee end, eince‘the method
ee given by Piecher will not teke cere cf thie, givee
e method for ite elimineticn in emell emounte.

(7)

1.

2.

3e

4e

MATERIALS, Arum. REAGWTS

Beperetcry funnele
100 ml. eiee Kimbell hex funnele were need.
All pyrex gleee etill
Calorimeter
Klett-Bic inetrument no need with the ertificiel
light ettechlnent.
rhctelcmeter
Genoa-Shaman! Phctelcmeter ueing the

Oencc he. 3 green filter.

Bolut icne end Reegwnte. ,

1.
3e
3e
4e
5e
6e
7.

8.
9.

Btenderd codeine eolution
Chlorofcn (redietilled from pyrex)
Gerbcn tetrechlcride (redietilled fron pyrex)
Dithieone in chloroform (26 ng./ml.)
Dithieene in Oerbcn tetreehlcride (25 mg./ml.)
Edietilled weter (redietilled from pyrex)
sodium hydroxide .251 (c. r. chemicel 4...“...
in redietilled weter)
Hydrochloric ecid eolution - l 15.
Sodium cum. . 25% (c. r. chemicel in redid-
tilled enter)

(8)

10. Poteeeium ecdiun tertrete . 25% eolution (c. P.
chemicel in redietilled weter)

ll. Scluticne of vericue foreip icne.

(9)

To prepere e otenderd cedmiun eolution the fol-
lowing methcd no found to be convenient. e eolution
cf cedniun nitrete wee mede up oo thet fifty milli-
litero of eolution were epprcxinetely equel to one-
tenth gree of cedmiun. rm. eolution woo otenderd-
ioed by oeverel “no.

Fifty-milliliter pcrticno of the eolution were
eveporeted to dryneee with e milliliter of oulfuric
ecid (dilute) in pletinum dieheo. The exceee ecid woo
thee fumed off end the codeine oulfete thus formed ig-
nited ot five hundred degreeo in e mffle furnece. lt
no found thet treeeo cf eulfuric ecid might be left;
thie wee, therefore, removed by noiotening the reeidue with
woter end egein fuming off eny reniuing oulfuric ecid.
thie proceeo wee repeoted until ccnotent weighto were
cbteincd on the reeidue. fhio procedure io givn in
detoil in Hillebrend end Lundell (8). A eeriee cf ouch

deteuinetiono ave the following reeulte.

Sample 1. 2. 3. 4. 5e
Codeine/5O nl. .1012 .1013 .101. .101: .101.
Since the reeulte obteined from the codmium eul-
fete method ere likely to be in error due to the in-
(10)

complete remcvel of the eulfuric ecid or due to lcoe
by opettering, e eecoml oerieo no run by none of the
electrolytic depceiticn of cedmium on e platinum geueo
cethode from on elheline complex cyenide eolution.
(‘l'reedwell-hll (9); Eillebrend end Lunaoll (10)). on.
reeulte cbteined on four oempleo were: - A
”pie 1. 2. 5. 4..
g. Codeine/50 ml. .101: .101: .1013 .101:
on. velue .1013 g./ml. we. then token eo tn. cedmitlo
ccntnt of the etcclr. eolution. A otenderd codeine
eolution wee preporcd by diluting fifty nillilitere of
thie eolution to one liter in e volumetric floor.
Twenty millilitero cf the reoulting eolution were
nude up to e liter in another fleck. The reeulting
oolut ion conteined two-nillicntho of e gree cedmiue
per milliliter or two eicrcgreme of cadmium.

An odditicnel oerieo wee run where the cadmium
no preoipiteted eo the cedmium emcniue phoophete.
Since thie method, due to inedequete pH control, ie
prone to give low reeulte. theoe reeulto were not in.-
cluded in the everege, but were merely need to give

(11)

further evidence of the unreliebility met with in thie
method. The following reeulto were cbteined with five

ouploot

Sample 1. 2. 3. d. 5.
3. 01/50 ml. .1000 .0999 .1001 .1003 .0997
Thin procedure followed thet given by freedwell-Hell (ll)
It woo found by teoto upon the cerbcn tctrechlcride
end chloroform cbteined from etoch that they were un-
ouited for deteainetlono with dithieone, eince thq
ocnteined eppreoieble enounto of neterielo giving color
with dithieone. Hence ell chlorofcne end cerbcn tetre-
chloride need were redietilled fru en ell-pyrex gleee
etill. Similer rcoulto were cbteined in teeto upon
dietilled weter cbteined free the tepe due to the
copper end leed token up from the pipeo. the diotilled
uter mt eloo be redietilled previouo to one.
Solutiono cf oodiun hydroxide, eodiun citrete,
poteoeiun oodiue tertrete end hydrochloric ecid were
uede by diluting c. P. reegento with rediotilled
weter. on. ecdiun pcteoeiulo tertrete end eodiue cit-
fete oolutione were found to be eufficiently pure for

(1a)

me if melon with euoceoeive mll portioue cf dithi-
eone until the pure green of the dithizone ie unnodi-
fied upon choking. The oodium hydroxide end hydro-
chloric ecid oclutiono could not be purified in thie
ny; however, they were found to be eufficiently pure.
Since e etrungly elheline eolution io need in the
extraction of codeine, it will be found thet etching of
the glue hey tehe plece olowly with ouboequeut depo-
oiticn of trecoo of oedmium; hence, it will be neceooery
to cleen the oeperetcry funnelo frequently with o
otrong ecid eolution. Ordinery cleoning eolution no
need for thie purpcoe originelly, but it no found thet
eny elight treceo of the chronte which my be left
will oxidize the dithixcne; ccnoequeutly, e eolution of

nitric ecid no need efter thie.

(1o)

PROCEDURE

For the colorimtrio determinetion of cedmium ee
the complex dithieomte only one mthod ind been de-
veloped until the epring of 1959. in 1937 Piocher end
lecpcldi (6) firet worked with dithizcne in connection
with cedmium end need the following procedure.

To five to ten millilitero of epprcximetely neu-
trel oedmium eolution en equel volume of ten per cent
ecdium hydroxide eolution no edded. Any iono which
might preoipitete with ecdium hydroxide were held
book by meene of mchelle oelt. thie eolution no
extrected repeetedly with dithiecne in e oeperetcry
funnel until the cerbcn tetrechloride no no longer
colored red. the combined extrecto were then nohed
with three per cent ocdium hydroxide twice end weter
once. on. red cadmium dithieonete no decompcoed by
meeno cf ncml hydrochloric ecid end the green color
of the dithiecne ccepercd. An eccurecy of within
five per cent no oleimed with thie method.

Since the work with the ebove method, one other
method for cedmium heo been recorded in the publiohed
litereture by B. B. Sendell (7). The procedure need

(14)

by Sendell io no followo: The oemple wee extrected with
dithizcne in cerbcn tetrechloride end the cerbcn tetre-
chloride leyer drown off. Thie extreot no oheken
with one-hundredth ncrnl hydrochloric ecid to remove
the cedmium leeving the meJcr portion of the other
metelo preeent behind. The nter eolution no then
trenoferred to e flet bottomed tube. Two end five-
tentho millilitero of twenty-five normel ocdium hydrox-
ide no then edded out the eolution choken with dithi-
ecne. l.lhe cerbcn tetrechloride leyer no then ccmpered
to otenderdo prepored by diluting otenderd omounto of
cedmium to the one volume eo the unknown, edding the
oeme emcunt of ecdium hydroxide end then choking with
dithieone. '
However, working with lead in connection with
eprey reeidue control on fruito, O. B. Iinter, E. J.
killer, end cthero (13) et Ilichigen State College in
1935 developed e method ueing chloroform eo oolvent
rothcr then cerbcn tetrechloride, which followed the
procedure of Fiecher end Leopoldi rethcr clooely ex-
cept in minor deteilo until the finel extraction of
the dithiecnete of iced. Ether then decompceing the
red complex end oompering the green dithizone, they
(16)

canpered the extncted dithizonnte. The reoulte ob-
tained were claimed to be et least as accurate no theoe
cbteined by Piocher end Lecpcldi end the procedure wao
oho rtened coneiderebly. Chlorcfozm no oubotitutcd
for cerbcn tetrechloride becauoe of the greeter eolu-
bility of the complex“ in chloroform.

in 1936 Clifford end Viohnen (5) of the United
Steteo Department of Agriculture publiehed in the
J. Off. Ag. Chem. an erticle deeling with the methcdo
for lead end oubmittod a new method whereby the oepere-
tion of the exceee dithizono no eliminated, hence
ohortening the procedure etill further. The accuracy
no increeeed, they cleimed, due to the lock of nececeity
of repeated extrecticne to remove the exceee dithieone.
The optimum pH no choeen end a oingle extreoticn cf
the eolution mode with exceee dithieone. Thie exceee
no ellcwed to diotribute between the equecue end the
chloroform piece. The mixed dithizone-dithizcrmte
no then compared with etendnrdo prepored in the come
ny.

The pooeibility of applying theoe laot too meth-
cdo to the determinetion of cadmium hao given rioe to

(16)

to the work in thie report.

It no found by experiment however that at the
ellmlinity beet ouited for the greateet extraction of
cadmium an the dithieonete, the exceee dithizono went
over into the aqueoue phaee too readily to permit the
uee cf the mixed color method. At a lower pH it one
found that the cadmium no not extracted quantitative-
ly. The work in thie paper lo ccnoequently limited to
a review of the method of Fiocher and Leopoldi, and to
the development of an acceptable procedure for the uee
of the red cadmium dithieonote.

The procedure adapted for the work in thie paper
on the determination of cadmium differe oligitly from
that prcpcoed by Piocher and Leopoldi. It no foumi
by reoulto in the laboratory that differencee in vol-
ume of the aqueoue eolution when a ccnetent volume of
cadmium found in the chloroform extract. The effecte
of verioue amounto of nter eolution to twenty-milli-
litero of chloroform solution are ohcn below. Each

oample contained a oonetent omount of cedmimn.

(l?)

Volume of Amount of Amount of

aqueoue eolution cadmium preoent cadmium found
10 ml. 2.0 microgr. 19.5 microgr.
15 ml. 20 " 19.8 "
20 ml. 20 .. _20.o .
25 ml. 20 T 19.6 r
30 ml. 20 " 19.3 "

Taking thie feet into ccnoideration the following pro-
cedure wee develcpedr

To an approximtely neutral aliquot of cadmium
eolution five millilitero of twenty per cent eodium
hydroxide no added and the aqueouo eolution no mdo
up to twenty millilitero with rediotilled nter. Suf-
ficient dithiecno in chloroform (25 mg./liter 0111313)
no added from o buret in one-milliliter portioue with
choking after each addition to cauee a dietinct exceee
to be preoent. Tim preeence of the exceee dithieone
may be noticed by the yellow color imparted to the
aqueoue phaee and a alight purplioh color to the chloro-
form leyer. Sufficient chloroform no then added from
another buret to make the total chlorofcn-dithiecnete
extract up to twenty millilitero. The chloroform loy-
er no then removed to a oeccm oeperetcry funnel con-

(18)

tainins twenty millilitero of three per cent oodiun hy-
droxide. ohaken up and allmd to oeparate. The chloro—
form layer io again drawn off and waahed with twenty
millilitero of rediatilled water. One Inching with
ocdium hydroxide wao found to be ac effect ive aa two
waohingo. The waehod dithioonate wao then drawn off
and compared agaimt a otandard in a calorimeter. If
foreign iono were mount the procedure waa carried out
with the addition of oodiul citrate or potaooium aoditlo
tartrate. The amount of cadmium preoent in the eolution
io read off of a calibrotion curve obtained by plotting
the reading on the calorimeter auinot the concentra-
tion of known oolutiono. he following concentration
were taken to plot the curve:

.001 mm, .0025 mg” .0050 013., .0100 me" .0160 103.,

.0200 mg., .0250 mg.. .0300 mg.. .0350 mg.
it no noticed that concentrationo higher than than
lioted above when uoing a otandnrd of .0200 me. were
out of the convenient working range of the colorimeter.

Thie calibration curve according to Piocher and
Leopoldi (13) 1o a linear curve while Winter, liiller.
and othero (12) working with lead found the calibra-
(l9)

tion curve to be a hyperbolic function. It wao found
by thio obeerver that if the otandard wao oet at a
conatant reading and the tangle varied that a curve
to obtained oimilar to that obtained by Iinter and
Miller for lead, which woo diotinotly hyperbolic in
character. The comparioon of the complete range, how-
ever. wao not poooible without a change of otandard
oetting and interpolation from that oettine to the ori.
ginal oetting which wao taken ae twenty. we eliminate
thio difficulty it wao found sufficient to oet the
oample rather than the otandard at a conatant oetting
and vary the atandard until catching io obtained. In
thio manner, choooing a oetting of twenty-five for the
omnple, it wao found pooeible to compare directly
without interpolation mpleo between acre and thirty-
five micmgrano of cadmium. 1t wao aloe found that by
thio: meal a linear graph wao obtained, therefore facili-
tating reading and increaoing the accuracy of reading

the graph. The data obtained for plotting the curve io

given below:

(20)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

 

  

 

    

 

 

 

11m.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

.....

 

 

 

 

 

 

 

 

 

 
   

 

W1. .. 11.. 17.4- .. . . .2... . 21W .1 W
.. . . .. .1 a 1 .

W. W 1W W. W ..... H. . W me W W
W . WW ...... W 1W. . W
.. ........ . 1.... . . _. .W 1 ... W
. 1 .. .1 ... . . .4. 11111 1 . 1
. _ . 1W.. I‘lfhl.-+1 1.. . 1 111W I 11.1.1111 11W; III 111
1. 1.11. .1. . ..... .... W W . W
... 4W 11 . n 1 u . W W W . .

i ..... ._ .. 4W ....... _~ W. .. ... W W w W
...“..WWW . W .W WW1 H ... .W . 1 W W .W
.1 W .. ... .W . . .. . . W .. 1.

.- W W W W... . . T W _ _ W . _
1 7.1-1.1111 .W .1. .... . .W. .. . W W 1 . .11W111 .1 ,. ._

.......... . 1.... ... +11v.tw. ’11 .1.. _ . . . 1 11 t .. . w _

W ..... . W. . ..... W. . .1 .1.—. .. in. n .1. 11. W . W . . .... ...W 1
. ..... . .. .. 1;. .W1 ,,,,,, . 1. . 1 ... . . _ . .. _

_. . 1W .1 . ... 1. .W .. .1 . W . . _ W1 1
. ..1W . .4. W ..... ._ o . W . .— 1. . . W . W . . ..... ..W W
7. 1 ...... . . .1 W . V

... ...... . .. . 1 ..a __ i i . .1 1 ... .. 1 . 1 . W .

i . . .H _ r..1.1..111L-.11.11.11...11.W- . . 111.1 . k . .W 1. 1 _ 1. .

.1. . .1. .1 .W ..W. 11,. W. . _ 1 +1 1 . . . W- .W .1. i W
W ...... . .. .. 1... .1 . . 1 .11 -1 1-1 W. 1 W. W .

1 . .1.. TWA . 1... .._. . .1 .

11%....WW1. .. W; ..... ..W __ 1 . W W
.........W .... m ... _ .

1. . ..W .._. 1... .. . _ WW
.... .... . 1 n _

.1 .._ .1-.-.1 W _. W
....... W. ”.1.“. ..

...... n 4. y

W. W .. n

.. L W1. W. 1
W ... 1. ; . W

W .. .11 1 _

1 1.. .111 . . . W 1. .-W1
...... ..W 1., .... . 1:11.41.
1. . ... W 1.. .1.... 1.. 11.1.1...“
....... 1 . W . 41W

1. W . W .. .W1
....W11LWW .W . . ..ff

. ... _. 1 1. WHJI
. 9 w i '

11-1. _. . W . -.«J 1..

_ _ .1i.1 1. .111

. WW . _. . . ..p1l11

...... . ... 1. ..T1vL
.. ...... _ . . .1. 1 KDJWWq
... .. .W. . . 11- .. ..-
.1 W 1111 W J. ....1olmldni
1 .. WWW. . 1.”...4

.. . .1 1. . . ...lwl
.. ... .11 . . ......L
.. 1.1 . . . 1
. . .W ...... . W1 1+..W w ...:
. ..... ..W .W... ....11

.. .. . 1 . .. ..11..1..
. ..W. . 1mm ..... — I L1.
4. .W 1. . .1 ...
W 1 1%.”.-.
. ._ ._ _ 1.1.. .....l
. .W .1. 1.1.1.3 ... .W ._. 311.11
. W. ....... .31. . W. . .1 .gWi
. .. . 11W 1 111.1

1. 1.1.. .. 1+.1Illlll1W1111111111111 11 i. 1.1 .

n1 . ._ 1 .1 W 1. 4er1...
. . .. .1 .

W . .1 . W W 1 .1. W1.
. W W W .. _ 1. .W. 111 1.1
. W W .W W. W . W. ..11
. W .1 W W .. Z W...
1 I W W . .1 1
. . .W- 1111.11

— .11 ...... 1 . ..I. {1..-16:1 1‘1 1| 1 .111101I‘J J i +1 W11 '1‘!- iol‘l ti .1 W1 _ :1... .1 I115] .uiiRLI 1.! Iq.|.t!illl I14. -1. .

_. . . . , . . _

. ..... . _ _ . . 1 _ .

. 1. W . W. W .. -r W W . W W _ _ W1 .W

F . . .n . 1.1.. W . ._ W. v1W . . 1

. . . W ..- _ . 1. . W W W W W . ..

W _ _ W. . . . .._ 1 . . . .

W W W1 ........ W1 W 11. .W W .. i W. W .. i. W 1.
1_ .1. . . — . _ . . _. _. _ 111i

. W . _ . . . . W- .1 .....1111111 1111.11.11..1.W1.1-.1.111-.:.111 1-1-1.11 ., 1.1.- .-.-..1,1111111-1.11-11 1.; . - .11“;
r o 1 4 1.1.11.1 1141141141 141 .1_.111l.|.|.1..|fil.1|tlilolfvi1..v1 ..1 . 1W . W. ... W _ ._ .

. W. W. .n W . ...... W .. WW. W1.» . n 11

. . . . 1.. ..... ... 1 . 1 . .. i n
..... W _ W W .. W. . 1 e W- ... W . ...

._.. 1. .1 ..W ........ 1 ..... . W. ... ..... . W _ ... . ..

... .. .1 W .. . ...... , _ . MW .. . .

_ _ a . 1 i .u n — W
...... W, W.W.. .WW . .. ..W . .W _ 1. _ . .

. .1w11l.4alt..lolaIvL.l + w . h a m .Oleler ill] '11 i1... ..... 0.! {.01 elatilll
7.x... 1? W. . W W. W W 1 W W. . 1 .W ..W .W, . 1
....... W ... ... . .W ... W.. . W . . . W W.1 .. . u . .. .1 .

. . ....... . _ .... W. . . . W . .. 1. ... . W . W . _ u ..

71 ...... . . .. . .1 .. . 1 .. .. . . _. ... ..1._ 1

W1. ...... . . W . . W . . . . .. . . 1 . ...1 .1. .....
... . W .179. . W .. W W __ .. . . _. _ .1 . W . .W. --
Wm W _. .. _ 1. W. . ..... . M _ .. .. .. W.

W111--- . .1 1- W . W . 1 ..... 1i . 1. 1 W. 11.1 .1 1-1-..W- 1 1.111111 111111111111W114111111. ..4111 11...1.1111111..111.1.1.1

..... W . W 1. W. W. ... W .. .1 . _ W . _ . W .. . _ W W.

_H. W. ...... . ._ . . . . . .. . .. i . i. 1 I
.. .. .. . W. W W. W i W 1. W1 ... .1“ W .. .W _.
. .1. . . ... W .. ..

cadmium Calorimeter Readingo

IToIont
m8. 1. 2. 5. 4. averagp
.0010 2.4 2.3 2.5 2.5 2.4
.0025 3.8 3.9 4.0 3.9 3.9
.0050 7.3 7.1 7.0 7.4 7.2
.0100 13.0 12.8 12.6 12.5 12.7
.0150 18.5 18.8 18.5 18.6 18.4
.0200 25.0 25.0 25.0 25.0 25.0
.0250 30.0 30.5 30.8 30.5 30.6
.0300 56.2 56.8 35.9 36.4 36.8

Each at tho oorioo obovo no run on o. dittoront oot or
oamploo,

to o check up on tho accuracy and reproducibility
of the method oovoro]. oerioo of unknown oar-plot 11:

inch tho aporotor no unonro of tho cadmium content

(21)

woro run. Eho toblo hollow givoo tho rooulto of thou
oorion
Cadmium Found Cadmium Prooent Error

7/ 7/ 704 $6.

7.8 8.0 -.2 ~2.5
14.0 14.0 .0 .0
10.0 10.0 .0 ,0
21.8 22.0 -.a -1.0

6.8 6.0 h3 05.0
13.2 12.0 +1.2. 44.0.0

Cadmium Found

1,
20.3
87.9

2.0

9.7
16.1
88.1
10.1

3.9
26.3

5.0
18.0
. 3.9
16.1
20.0
11.9
30.0

8.8

3.5
17.8
19.5
24.9

21.?

0001011110 Pullout
'7’

20.0
28.0
3.0
0.0
16.0
23.0
10.0
4.0
26.0
4.0
11.0
3.0
15.0
30.0
10.0
21.0
8.0
3.5
17.0
19.0
25.0

22.0

(22)

Error

700. $00
..a +1.5
..1 u..
.0 .0
1.7 21.0
..1 4.1
4.1 ..0
..1 +1.0
-.1 4.0
ha (-08
+1.0 +40.0
IWho +28.5
..9 +00.0
+.1 ..7
.0 .0
+1.9 419.0
+1.0 -0.0
+.2 +10.0
.0 .0
..z +1.0
... +1.5
...1 - .0
-.a -1.5

Gad-dunxlbund

8.0
9.8
15.6
8.0
14.0
8.8
6.1
8.7
4.0

18.6

Cadmium Pnunt

7/

7.5
10.0
16.0

8.0
14.0

3.0

6.0
10.0

4.0

18.0

(33)

Error
'YCd
+.5 4.0
..3 -a.0
-.4 -3.3
.0 .0
.0 .0
+.2 10.0
+.1 1.6
-1.3 -15.0
.0 .0
+.6 5.5

Sinoo tho pnoonoo of an appreciable color in tho
blank dotomiuation I111 oauoo a variation in tho amount
of cadmium “and. tho ortoot of tho aging at roagonto
upon tho blank color I... .tudiod along with th. dovol-
omout or a auitablo proooduro. Tho roageut undor toot
no alloood to ago in ordinary glaao contaiuon uhilo
all othor roageuta ooro mad. up troah on tho day 0:
Mo. Tho folloring rooulta woro obtainods

1. 8041‘! hatroxido allovod to ago; dithiaono.
chloroform, and rodiatillod uator from our: day.
lot day . no porooptiblo color
and day - ho porooptiblo 00101-
30. day - no porooptlblo oolor
ono took .- oliat 00101-
too tom - blank or loo. than too-toutha nioro-
gran of cadmium.
2. Dithiaono alloood t0 ago other "agent. froah
oaoh day (dithiaoao but in hm bottla in dark.
at room tonparatura.)
lat day - no perceptiblo oolor
8nd day - no porooptiblo color
30 day - olight pinhiob oolor about .2 niorogran
on. not .- blank or about on. niorogron

(24)

too nook- - roagent oxidiaoo to the yolloo
diaaono upon ohaking.

Tho chloroform and rodiotillod Iator could bo uood at
long ao two to throo wooko with no perceptiblo color
boing notiood in tho blank. Tho dithioono lay bo uaod
tor a longer poriod than found abcvo if it in kept in
tho in. box. Dithioono pro-mod in a brown bottlo at
ioo box touporaturoo oaa round to giro only a olight
blank aftor otanding too rooko.

n. ungnitudo of tho blank obtainod from tho ro-
agonta my bo tairly-acouratoly moaaurod by plotting
tho roadingo obtainod from tho conpariaon at tho blank
with docroaoingly mall amounto of cadmium. For thio
pnrpooo oamploo containing 1.0, 0.7, 0.4, 0.1 micro-
gnano 0: cadniun pluo tho blank in oach 0a.. woro con-
nrod to tho blank. 1h. comparioono 9v. tho rooulto
liatod boloo inch Ihon plottod in tho armor for tho
main graph and oxtnapolatod to nor. rooding can a
valuo of approximtoly 0.8 nicrogrola tor tho blank.

1 otonaard. ootting 0: ton no uaod for tho unploo

fill. tho blank Ina variod.

(25)

Cadmiu- Prooont

1.0
0.7
0.0

0.1

Colorimtor Reading.

1.
50.0
56.1
86.7
18.1

(26)

2.
49.9
36.0
86.8

13.0

3.
50.0
56.0
86.9

13.3

hriouo worker. 13'. done their reoearch into the
detection of traco metal. with dithizono uoing both,
carbon totrochlorido and chlorofona. Thereforo, a dio-
cuooion of the moist iv. merit. of the two no a oolvent
for cadmium dithizonato 1o pertinent. It no noticed
with carbontetrachlorido that emuloiono foam! 1...
readily due to tho lower eclubility of carbon tetra-.-
chlcrido in water. The motor difforonc. in the huo
of color. of tho dirforent dithioonatoo i. o footor
giving a groator dotection pooaibility in carbon tot-
rachlorido, but at tho eon. tin. thio advantag. 1a
offoot by the foot that at hiehor concentration. any
of the motallic conploxoo or. 1... 00111111. than in
ohlcrofom. m. 1. true of tho oadniun conplox. it
woo noticod that abov. about twenty-fir. nicrogrann of
oodninn the roedingo obtainod with the calorimeter
were very noarly conotant indicating oaturotiou of the
carbon totrachlorido. Ihio difficulty 1. not onccunt-
orod with chloroform.

Becauoo of the fact that the diotribution ratio
of dithiocn. botweon the water and corbcntetraohlor-
id. phaee. i. more favorable for tho one... to go over
into the water phat. than with chlorofo'm, the one...

(27)

dithioon. can be nor. oaoily waohed out when noing
carbon t.trachlorido than when uoing chloroform. Thio,
howewor, aloc eliminated the poooibility of uaing tho
oenoitivo mixed color mthod for the comporioon of tho
oamploo, oince thio method dopendo upon the diotribu—
tion of the exceee dithioono between the water and the
oranic phaooo. By the no. of chloroform for the ex-
traction, tho pH range of stability of the metal con-
plemoo of dithixon. io inoroaoed, at timoo aiding tho
oeparat ion of certain foreign iono from the dooirod
metal. The dociding factor for the no. of chloroform
for the work in thio paper we. the fact of tho greater
oolubility of the cadmium dithiocnato in chloroform,

heno. incroaoing the working range.

(28)

u \ ‘i
\\b. \t 1

ft \\ W....\ v

5 ‘\ Pwlto \ .udo.1l\i all“ 4.1. 0“ 01.1‘1‘

 

 

Due to the fact that many opentora are incapable
of linking accurate optical comparieono. a mthod ueing
tho 0enoo-3hoard-8anford photoelectric calorimeter wee
developed. The came procoduro ao need for the optical
colorimoter we. found to be oatiofactoxy for no. with
the photolomotor. Howovor, extra care not he need to
aecertain that no dropleto of water are lot into the
chloroform layer inch would cane. .rronoouo reoulto
men reed on the phoelometer. Several oerioa of eamploo
wore run on the photolometer with tho reeulte which fol-
low lator. The greon Conco Ho. 2 filter wee nood with
the greatoet opined of reading. for the range in 011..-
tion. on. nximum tranemiooion of the filter 1. given
ao 525 millimicrone, i111. preliminary rune upon the
dithizonat. in chlorofom chow a maximum aboorption
at 520 millimicrono. 9h. data which followe below

givo. the reoulto of toot upon the four cenco filtoro.

Filter Ending.
5 1’ 0.011101. 20 Venom... 5p...
1 03.5 53.0 20.5
a 71.5 40.0 51.5
5 99.0 98.0 1.0
4 97.5 95.0 1.5

(39)

.e
......
......oo.

18-. 7" 6 one 0

.o—oweeoee
......o.
0 0“.

O

... a.
o .t..
...1'

0-0
'.
0

...-~00“ .
.eoooovO-
....

.
t a

...-0‘0‘
....ooe-
..-....

' I
1....
- I

....o o-

o

‘0.

.
......oe
.....e.‘

3,699
...-0...
...—.0000

ea.—
9

I;
r

I‘-
0
.
7
:.
...";
0
I
'0

..
c

 

 

 

The photelometer roadingo wore calibrated in termo
of micrograme of cadmium by plotting reading on the
photelometer againet the concentration of cadmium. 1h.

reenlte of the calibration are given immediately below.

cadmiumLPraaont

0,9 1. z. 5. 4. Average
1.0 89.5 89.8 81.0 89.4 89.4
4.0 76.7 78.0 77.3 76.6 76.7
8.0 66.9 66.9 66.7 67.0 66.8
12.0 58.0 58.3 58.1 58.0 58.1
16.0 50.0 50.0 50.0 51.0 50.0
20.0 45.0 45.0 45.0 45.0 45.0
84.0 59.7 59.8 59.5 59.9 59.8
28.0 56.0 55.9 59.8 56.5 56.8
52.0 53.6 55.0 55.0 52.7 52.8
56.0 50.0 50.0 50.0 50.0 50.0

Photolometer Reading.

1h. reading. which or. crceood out were not inclndod in
the average reading. becauoo of tho great differencee.
Uoing the calibration curve obtainod fro. plotting the
above data, the following reoulto were obtained on

eevoral eerieo of unknown oamploe.

(30)

Cadmium Prooont
0’

10.0
80.0
8.0
4.0
8.0
6.0
50.0
16.0
80.0
80.0
10.0
10.0
6.0
8.0
16.0
83.0
6.0
10.0
18.0
16.0
8.0

8.0

Cadmium Pound
4V'

10.5
19.5
5.1
4.5
5.0
5.0
29.0
11.5
52.0
20.0
10.1
10.1
5.0
11.5
17.0
22.0
5.0
10.5
15.5
15..
2.5
5.5

(51)

v/cdflrrcrficd
+.e +5.0
-.2 .1.0
+.1 +5.0
+.a +5.0
.0 .0
.0 .0
..1.0 -5.5
.1.. -5.0
+5.0 +10.0
.0 .0
+.1 +1.0
+.1 +1.0
.0 .0
+5.5 «5.0
+1.0 +5.5
.0 .0
.0 .0
+.5 +5.0
+.5 +1.1
+.4 +5.5
+.o +10.0
+.5 +5.5

CadmiumsPreeent

9/

4.0
4.1
20.0
8.0
16.0
18.0
6.0
10.0
8.0
14.0
7.0

Cadmium.iound Error
9/ 1/00 400
4.0 .0 .0
4.0 -.l -2.5

19.8 -.3 -l.0
5.2 +.a +2.5
15.5 +.5 +1.5
18.0 .0 .0
5.8 -.2 -5.5
10.0 .0 .0
2.1 +.1 +5.0
14.5 +.5 +5.6
6.7 -.5 -4.5

(32)

do mentioned before in thio report, Piocher and
Loopoldi av. the following iono a. interfering with'
the extraction of cadmium a. the dithiocrmte. oilver.
gold, palladium. copper, mercury, nickel. cobalt. and
nine in large amonnto, ae well no any iono which would
pocipitate in the alkaline eolution need for the ox-
troction cf the cadmium. Theo. metal. which were found
to procipitato were held back by tho no. of Rochello
oelt. Sondoll (7) found that thio mothod woe not eat-
iofactory in holding up man... which interfered
with the complete precipitation of the cadmium dithi-
oonato. Chromium ao chronic ion woo found to give tho
eon difficulty in addition to giving a alight pinkioh—
purplo color to tb extract.

in the work that followe tho follwing iono were
.mma for their effect on the extraction of cadmium
and. more method. wor. not given by the litoratnro for
tho removal of any interference. attonpte wore and. at
developing euitablo proceduroe.

Th. iono were. calcium. phcophato, ferric, cupric.
biomuth. load. cobalt, nickel, sine. etrontium, barium.
chronic. areenioue. and oilver.

It woe found that calcium did not give difficultiee

(53)

with the procedure a. develOped originally in thia

paper. a oerieo of determination. ave the following

reeulte.

Cadmium Cadmium Interfering Error

112.395. 953/55 139 you , $05
20.0 20.0 101/ Ca .0 .0
20.0 20.0 501/ Ca .0 .0
20.0 20.0 1009’ o. .o .0
20.0 20.5 1509’ 0.. .6 2.6
20.0 19.8 8007/ Ca -.2 wl.0
30.0 19.8 8509’ 0a ..2 -l.0
20.0 19.9 5009’ 0. -.1 - .5
80.0 19.9 5504’ Ca -.1 - .5
20.0 20.0 4009/ 0a .0 .0
20.0 19.7 5000/ Ca -.5 -l.5

who reoult. abcvo are all corrected for a blank on the
calcium oolution and reagent. of two microgramI. All
comparioono above were mad. on tho photelcmeter. No
additional procaution. appear to b. noceeeary than
thoee noceooary in tho ordinary procedure.

rho pnoenc. of the phcaphato ion aloc appeared
to cauc. no difficulty. 1 oerieo of doterminaticn made

in tho preocnc. of phcophato ion av. good rooulto with

no additional precaut iono.
(54)

Cadmium Cadmium Interfering Error.

Proeent Pound Ion 705 504
V 0/
10.0 9.5 100-y 204'3 -.2 -2.0
20.0 19.9 200‘1' - -.1 - .5
10.0 10.0 5001/ i .0 .0
14.0 14.0 400 0/ .. .0 .0
10.0 10.2 500 1’ . .5 2.0
4.0 4.0 400-5/ 5 .0 .0
15.0 15.9 500 v . -.1 ..5
10.0 10.2 200 0/ i .2 2.0

7.0 (oompl. off color - no reading. pooeible)
To aocertain the effocte of larger amount. of phoe-
phate ion upon tho accuracy of the reoulto the follow-

ing oorioo we. run.

(35)

Cadmium Cadmium Int orf. ring Error.
Prooont Pound Ion «Cd fled
./ .x .
10.0 9.8 1.0 gro. P04 -.8 4.0
20.0 20.0 1.0 gro. '- .0 .0
10.0 19.2 1.0 gre. . .2 1.1
2.0 5.0 1.0 gre. . 1.0 50.0
5.0 5.5 1.0 gro. . .5 5.0
22.0 22.5 1.0 are. . .5 1..
11.0 15.9 1.0 gre. 9 ... -1..
50.0 29.4 1.0 gro. 4 -.5 -2.0
25.0 25.5 1.0 g... . -.2 - .5

 

Ferric iron, one of tho iono precipitating in
ouch alhlino oolutiono. canoe. great difficultio. be.
came of tho fact that part of the cadmium dithioonato
ia abocrbod 0n the .urfac. 0f the ferric hydroxide
fcnnod. the folloeing dato give. reoulto obtained

when nothing i. added to hold up the iron.

Cadmium Cadmium Interfering Error.
Preoent round Ion 10d
v v
20.0 11.5 .5 mg 1. *3 -5.5 .42.5
15.0 0.0 .5 ma " 37.3 “5.0
5.0 4.0 .5 mg 9 ...0 .50.0
4.0 1.5 .0 l8 ' -3e5 I53o0
2.0 .5 .5 mg 5' +1.5 415.0

By trying vnrioue concentretion. of pctaeoium ocdium
tortroto and ooditun citrate. tho boot ooncontration
... found to In five 1.1111115." of 25% may... of
oitrat. in tho twonty milliliter. of eotor eolution.
Doing potaooium aodium tartrot. the following reeulto
for the determination of cadmium in the preconce of

a lull amount of iron.

(56)

Cadmium Cadmium Interfering Error.
Preeont Found Ion yCd
Y ’Y
2.0 2.2 .5 mg r. *3 .2 10.0
5.0 5.1 .5 mg - .1 1.5
10.0 10.0 .5 mg a .0 .0
14.0 15.5 .5 mg 5' -.2 -1.5
15.0 17.7 .5 mg 5' -.5 -2.0
22.0 22.5 .5 mg i .5 1.5
20.0 20.1 .5 mg a .1 .5
15.0 15.5 .5 mg 5' -.4 -2.5
12.0 12.1 .5 mg - .1 .9

nth larger concentration. of iron running a. high a.
four milligram. per twenty milliliter. of aqueouo oolu-
tion, tho following rooulto were obtained ueing fiv.

milliliter. of 26% pctaooium ecdium tartrat. to tie up

(37)

the iron:

Cadmium Cadmium Intorforing Error.

Prooent Pound ion «Cd 10d
1’ ’Y

.5

10.0 9.0 1.0 mg n ..2 -8.0
10.0 9.5 1.5 m . -05 -6.0
10.0 10.2 o.0 mg 3 .2 2.0
10.0 10.1 2.5 mg 5' .1 1.0
10.0 10.5 5.0 mg . .5 5.0
10.0 10.4 4.0 mg '5. .4 4.0

.1... tbs citrate. have 59.5 used with great

.1105... in tying up iron in th. determination or

nichl .. th. dimothyl glyoxiu. .alt, .odiun citrate

I. trial in thi. dotonninnt ion with tho 1'01le

".111".

uled.

0.5mm

Pruont
Y

10.0
10.0
10.0
10.0
10.0
10.0
10.0

10.0

admin
round

4/
10.0
10.3
10.2

9.7

9.8

10.3-

10.0

9.7

Interfering
Ion

.5 I8'Pb*3

1.0 mg
1.5 mg
2.0 mg
2.5 mg
3.0 mg
3.5 mg

‘00 mg

..

--.

..

ll‘ror.

v0.

.0
.3
.3
.8
.3
.2
.0

Five milliliter. of 25% .odium oitnt. nor.

7155

.0
3.0
2.0
3.0
3.0
2.0

.0

3.0

In .11 .ttcmpt to find it other poly-hydroxy

cranic compound. oonld b. 11.00 to tie up the iron,

. .erio. of dot-mimtion were run nning glycerino.

2h. tolloring table .1101. tho nonlt. obtnined vith

nrion. conocntration. or iron.

(38)

cadmium Cadmium Inte uterine ' Error.

Pr..ent Ponni Ion yea, $00
4/ 4/
2.0 2.1 .1 mg n+3 .1 5.0
5.0 4.5 . .2 mg ~ .2 ...0
7.0 5.7 .5 mg 9 .5 .5.2
10.0 9.5 .2 mg 9 .2 . -2.0
20.0 20.5 .4 mg . .5 1.5
50.0 29.5 .5 mg i .4 -1.5
10.0 9.1 .5 mg n .5 -5.o
10.0 9.5 1.0 mg 9 .5 .5.0
10.0 9.5 1.5 mg 5 .1 . .7.0
10.0 9.5 2.0 mg 4 .5 -5.0
10.0 9.2 2.5 mg 5' .5 -5.0
10.0 10.0 5.0 mg '3 .0 .0
10.0 10.0 5.5 mg i .0 .0
10.0 9.5 4.0 mg 5 .5 -5.0

One 1.1111115» of glycerin. moi. 55.51.515.11: 1.
many tin. that actually neoded to tie .119 the iron
preeent Ia. used. in each can. In both the table.
above it can be can that the predomimnt tendency

i. to be .ligxtly 10.. However. no precipitate c:
terric hydroxide .a. note... The 11.. or . h1g5” con-
centration of glycerin. ea. not tried in. to the fact
that a very large men. over that theoretically need.-

(39)

.d ... uaed. it i. etident from th..e noult. that
glycerin. i. not a. .atiefectory a. either p0ta..ium
.odium tartrate or .odium citrate.

Iith cuprio copper and .ilver reeul t. were ob-
tained .imil.r to then found by H.011” and Leopoldi
(6) who .xtuoted .nall amount. of thece ion. by a
previou. extraction in .n acid .olution. 1h. eolution
u.ed for thi. extinction had .n .pproxinate pH value
of 4.0. a .ubuquent extraction by the 11.11.). method
for cadmium are ..ti.f.otory ncultc. Hanover, with
large amount. of .ilver and cuprio capper. it v... in-
poceibl. to extract then interfering ion. completely
oeuai to get comparicon. on th. cadmium without
10.ing the bulk of the cadmium along with them. Th.
following rccult. were obtained with a our» content
up to one hundred micrograms
admin Error.

cadmium Interfering

(40 I

Pnlcnt round ‘ ion 70d 106.
‘V v
10.0 9.8 .01 mg Ag ..3 1.2.0
10.0 10.0 .04 mg 13 .0 .0
10.0 9.7 .06 me A; -.3 “.0
10.0 10.4 .08 me As .4 4.0
10.0 9.9 .09 me As ..1 -1.0
10.0 10.5 .05 mg Ag .3 3.0

Iithcut thio previou. extraction of eilver. the
yellow of the .ilver dithizonct. i. prcferentially on-
trcctcd and ob.cur.. the ccdmium color. The eerie.
run with cepper pre.ent .hond the .am. cffcct. - Five
who ..r. run without the .eid extrcction, .nd no
compcrieon. wer. ponibl. beceun th. yellc. cuprio
dithilcnete eb.cured the red cadmium color. The r.-
.ult. of fit. .emple. proviouny .cid extracted

.homcd the following recultu

Cadmium Cadmium Interfering Error.

Prnent Found Ion 70d 10d
’y o/ .
10.0 10.3 .03 mg “*2 .3 3.0
10.0 9.8 .0‘ mg '. -.2 -3.0
10.0 10.0 .05 mg .. .0 .0
10.0 10.5 .05 mg i- .5 5.0
10.0 9.9 .10 mg i ..1 -1.0

i 1.. mph. with larger amount. of ceppcr var. run
u.ing hypophocphoreu. .cid to rcduc. th. cuprio ion to
mctcllie copper much I... filtered off. neuter, due
to com. influence, then .amplcc tere found to b. .uf-
ficintly off color to parent .courat. comparieon.

BiImth and but are both extrceted in 81.131111.
.olution. but th. dithizomtn are theoreticclly decom-
poaed at the .lhlinity necenary for mo.t complct.

' 141)

.xtraction of the cndmium. Then two metal. were run
in a ...-1.. ucing five millilitcr. of 25% potenium
.odium tartrat. in the .trongly alkaline .olution.

i'he folloming rnult. were obtained:

Cadmium Cadmium intcrfering Error.

Prelent Pound Ion VOd ' 3105
4/ 4/
10.0 10.1 .5 mg Pb .1 1.0
10.0 10.3 1.0 mg Pb .3 3.0
10.0 9.9 1.5 mg Pb -.l ~l.0
10.0 9.7 3.0 mg Pl) -.3 -3.0
10.0 10.0 2.6 113 Pb .0 .0
10.0 10.5 .5 mg Bi .5 5.0
10.0 9.8 1.0 mg 31 -.2 -2.0
10.0 10.3 1.5 mg Bi .3 3.0
10.0 9.7 8.0 mg Bi -.3 -3.0
10.0 10.0 8.5 mg Bi .0 .0

Zinc in not too large amount., .trontium, bnrium.
and arnnic (ioucl .cemcd to give no difficulty in the
.xtraction cf the cndmium dithisoncte in the pre.ence
of either .odium citrat. or pot...ium .odium tartrate.
Zinc in large amount., honour, caund .n incre... in
th. intee. ity of color due to the .xtraotien of com.
.111. along with th. cadmium

For relatively .11-.11 .mount. of zinc. the follow-

(43)

ing relult. wet. obtained u.ing five milliliter. of

85,1 potanium .odium tartrat. or 25% eodium citrate

.. indicated.
Cadmium Cadmium Int erfe ring Error.
Precent Pound Ion o/Cd 520d
7 v
7.0 7.2 .10 mg Zn(cit) .2 2.0
10.0 9.5 .20 mg Zn 5 -.2 -2.o
20.0 20.4 .50 mg 5n 3 .4 2.0
15.0 14.9 .50 mg Zn '3 -.1 -1.o
2.0 2.5 .10 mg 55 3 .5 15.0
10.0 10.0 .20 mg m...) .0 .0
5.0 4.5 .50 mg Zn 5 -.2 10.0
25.0 25.5 .50 mg 2.1 .. .5 2.0

'ith larger amount. of zinc the following rnult. mere

obtained:

Cadmium cadmium interfering Error.

Prcnnt Found Ion 40d %Gd
0’ ’Y
10.0 30.8 1.0 mg Zn 10.8 103.0
10.0 39.5 1.5 mg Zn 19.5 195.0
10.0 39.8 3.0 mg Zn 19.8 193.0
10.0 30.8 3.5 mg Zn 30.8 802.0

Acecniing to Pinhcr and Leopoldi (6). the cadmium my
be precipitated a. th. mind. and. after filtering off
and redicolving. the cadmium my be extrectcd a.

(45) 0

previenuy. 'l‘hie, homever, ma. not attemted in th. work
of thie p.per.

a few additional .ample. are run with .trontium.
barium. and arcenic (ioue) vith the reeult. given in the
follodng “51.. Five 1.1111115." 55 25% .odium cit-

rate were added in .ach can.

cadmium Cadmium Int erfering flrror.
Pracent round Ion 705. 7.05
’Y ’Y
20.0 20.4 5.0 mg 8r .4 2.0
15.0 15.. 5.0 mg 55 .2 1.5
10.0 9.9 5.0 mg 55 -.1 -1.0
5.0 4.5 5.0 mg 5;- ..2 -4.0
20.0 20.0 5.0 mg 5. .0 .0
15.0 14.5 5.0 mg 5. -.2 -1.5
10.0 9.7 5.0 mg 5. ..5 -5.o
5.0 5.5 5.0 mg a. .5 5.0
20.0 19.7 5.0 mg 5.03 -.5 .1..
15.0 15.0 5.0 mg 1.03 .0 .0
10.0 10.2 5.0 mg 1.03 .. 2.0
5.0 5.0 5.0 mg 1.03 .0 .0

Since no method in. .. yet bcen devind for accur.
atcly accounting for wall .mount. of cadmium in the
prnence of large amount. of nichl. an attempt Ia.

i“)

and. to coin nu. difficulty. 51555.5 (5) uaed .tan-
nou. chloride to aid in the qualitativ. detection of
cadmium in th. pr...nc. of nickel and cobnlt. i‘hi. I.
tried with the qmntitativ. determination, but u. found
to b. uneuoc...ful, .inoe .ppreciehl. .mount of nickel
and cobalt wer. .xtracted .leng with the cadmium giving
. purpli.h color to th. eolution of cadmium dithinmtc.
the we... tin allc cannd a change in the color of
th. .xtraotz hcncc. thie id.a n. dilcardcd. 1h. pr.-
oipitation of nioh.l a. the dile glyoximcnlt n.
alec .ttenpted. it .a. found that .n .xcen of di-
methyl dyoxim. cau.ed varintion. in color. much var-
ied with the amount of di-mcthyl glyoxim. prncnt.
ihercforw. th. .xcen dimethyl glyoxime mt be moved
by treating with nitric acid. Eva after thi. a. den...
it w.. noticcd that email amount. of nickel nre left
which caund an off coloring of the axtract. Band.1l
in hi. p.per (7) .liminated the difficulty attendant
upon .nall ...... 5: nickel by extracting th. cadmium
in a .liatly amninal .olution. Hewevcr. h. dcalt
with .xtr.m.ly ..ll amount. of cadmium, about .3 micro-
grun. it wa. found. that with larger amount. of cadmium
complctccxtraction a. th. 415111.55». wa. not ponible.
011. following table exprenn remit. obtained by thie
(45)

eligitly amoniccal extraction of cadmium. No nickel

n. prennt in th... .amplec.

Cadmium Cadmium Error.
Prennt ibund 70d $Cd
”V A ’V
20.0 16.0 .nInonia oolution 4.0 30.0
15.0 12.2 r 7 2.5 21.0
50.0 25.5 9 - 4.4 14.0
5.0 4.2 5! . .5 15.0

The above rnult. indicate about .ighty pcr c.nt extrac-
tion .t the pH obtained. However. the per cent extraction
1. not content.

Binc. th. prccipitation of nickel dimthyl glyom-
in. i. not compl.t. .nough to nmov. the int trcce. of
nickel. and al.o that nickel i. extracted under the In.
condition. .. cadmium, thi. mcthod cannot give reeult.
for th. cadmium deteminetion.

An attempt n. mad. to prccipitat. th. cndmium a.
cadmium mlfide. having the nickel in eolution ueing
lead a. a carrier for th. .mll amount. of cadmium pr...
.ent. However, it n. found imponibl. to g.t compl.t.
pneipitation of cadmium without prccipitcting a
portion of the nick.1( hen“. the cam. difficulty i. en-
countered here .. in the precipitation of nickel a. the
dimthyl glyoxim “It.

(45)

Cobalt. inch along with cadmium and nickel 1. ex-
traot.d in th. alkaline .olution. could not b. rumov.d
by any of the method. attempted. ilethod. for the pre-
cipitation.of cobalt by hydroxylcmin. (14), and .nthra-
nilic .cid (15) er. given in the abetractc. but naither
of th... proved .ucc...fnl whcn tried. Cobalt then
could not be rnoved from the .xtract and a purpli.h-
bretm color n. alway. obtained. .

Chromium a. the chronic ion even in the pre.enc.
of citrate or tartrcte gin. a purpli.h tint to th. ex-
tract of cadmium dithiaormte, preventing .ny com-
pariccn with tim .t.ndard all}. give. erron.ou. rweult.
nth th. photelomcter. If pre.ent .. the diohronmt. the
dithicone i. oxidind almoat inmedintely to the dia.one.
Lara. amount. of nitrat. .111 all. oxidia. th. dithizon.
.lowly a. will pcntavalent areenic. Since thi. diffi-
culty c.nnot be .topped by nce of citrate or tartrntc.
cleaning eolution mnat not b. naed to clcan apparatu.
du. to the dunger of chromnt. being pre.ent. Lerge
amount. of nitrat. and .rnnic though probably .eldom

encounter.d mu.t be remov.d.

(47)

CONCLUSIONS

a mothod for the «termination of cadmium a. th.
cadmium dithisonate in which the rcd color of th. dithi-
acnate is compared directly ha. bnn developed both for
the optical .nd th. photclectric colorimtere. The
following ion. wer. found not to interfere under th.
condition. of th. experiment: calcium, phocphatc.
fcrric. barium, .trontium, arcenic (lone). unganoue,
biemuth. 1nd, zinc in not too large .mounte, and
cuprio .nd .ilver in .mall amountc. Nickel .nd cobclt in-
terfcre. cad no method w... found which elimimted thie

difficulty.

(48)

 

1.
3.

a.
4.

5.

6.

7.

BIBLIOGRAPHY
Piecher. 3. Ann. 212. 316-24 (1882)

Ii.ch.r, H. Ii... Veroff. Siemene-éonn.
4. 158, (1925)
r.print.d in '
Angcnndte Chem.
42, 1025-0 (1920)
liecher. H. Angew. Chem. 47, ‘585 (1934)

51.5555. 5. Angew. Chem. 50. 919 (1957)
Cliffoid and Iichuann H a
J. 15.55. Off. Ag. Chem.
19. 150 (1955)
51.55». 5. and 125175141. 0. .
Iikrochemic. Acta 1. 3042 (1937)
5.54.11. 2. 5.
Ind. 1: mg. Chem. incl. Ed.
51, 554 (1959)
11111.51“. .54 1.554.11 "11:511.. Inorganic Analytic"
John Iilcy .m. 555. 5.. 151-5, E. v.
1929 p.205.
25.....11451111 “Analytical Chantry"
John .11.: me... 5.. 155:, e. I.
755 .1. 1925 p. 159.

(49)

10.
11.
13.

13.

14.

15.

llllohnund .nd Land.11( 10c. cit. pp. 206-7
Mun-nun; 1... .1.. p. 192
fiat», 0. 3.. nobilon, 3.1.11 11., nub, m1. I..
.211 11111.». a. J. '

1nd. 11:13.01.-. m1. 111. 27, 865 (1935)
noon». 3. and 3.31.1.1. a. 1 '
‘ I1... Vomit. amazon. 1:. u (193:)
11.1.... J. 0...!»

Mo. 30.. hm. :1. am.

as. 1030-: (1930) o. 1. 25. :61 (1931)
rank. n. a. punk. ‘

3. 111.1. on... 93, 141-1 (1953)

o. .... :7. 4.497 (1933) '

(50)

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