The Detection and Determination of Antimony by Means of Rhodamine

Louisiana State UniversityLSU Digital Commons 1951 The Detection and Determination of Antimony by Means of Rhodamine B.. William Cornelius Hamilton Louisiana State University and Agricul

Louisiana State University

LSU Digital Commons

1951

The Detection and Determination of Antimony by Means of Rhodamine B.

William Cornelius Hamilton

Louisiana State University and Agricultural & Mechanical College

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Hamilton, William Cornelius, "The Detection and Determination of Antimony by Means of Rhodamine B." (1951) LSU Historical

Dissertations and Theses 7975.

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THE DETECTION AND DETERMINATION OF

ANTIMONY BY MHN.NS OF RHOBASHtlE B

A D i s s e r t a t i o n

S ubm itted to th e G raduate F a e u lty o f th e

L o u isian a S t a te U n iv e rs ity and

A g r ic u ltu r a l and M echanical C o lleg e

i n p a r t i a l f u l f i l l m e n t o f th e

req u ire m e n ts f o r th e degree o f

D octor o f Philosophy

inThe D epartm ent o f C hem istry

by

W illiam C o rn e liu s H am ilton

B S F ra n k lin and M arsh all C o lle g e , 19A2 M.S L o u isian a S ta to U n iv e rs ity , 1950

June 1951

UMI Number: DP69353

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MANUSCRIPT THESES

U npublished th e s e s su b m itted f o r th e m a s te r 's and d o c to r* s

d eg rees and d e p o s ite d i n th e L o u isian a S ta te U n iv e rs ity L ib ra ry

a re a v a ila b le f o r in sp e c tio n * Use o f any t h e s is i s lim ite d by th e

r i g h t s o f th e au thor* B ib lio g r a p h ic a l r e f e r e n c e s may be n o te d , b u t

p a ssa g es may n o t be co p ied u n le s s th e a u th o r has g iv en perm ission*

C r e d it must be g iv e n i n su b seq u en t w r i t te n o r p u b lish e d work#

A l i b r a r y which borrows t h i s t h e s i s f o r use b y i t s c l i e n t e l e

i s e x p ected t o make su re t h a t th e borrow er i s aware o f th e above

r e s t r i c t i o n s *

LOUISIANA STATE UNIVERSITY LIBRARY

119-a

The a u th o r w ish es to e x p re ss h i s s in c e r e a p p r e c ia tio n f o r th e

ad v ic e and p a t i e n t a s s is ta n c e o f D r P h i l i p W* W est, who d ir e c te d

t h i s In v e s tig a tio n * He i s a l s o g r a t e f u l t o Dr* K G Keen, Dr* G* Lee, and Dr* A I Le Rosen f o r t h e i r h e lp f u l s u g g e s tio n s , and t o Mr* Hans S u te r f o r th e a s s is ta n c e and ad v ice which he gave

H is h e a r t f e l t th an k s go t o h i s w ife , C la u d ia , f o r h e r c o n s ta n t and f a i t h f u l encouragement*

i i

TABLE OF CONTENTS

Page

I INTRODUCTION 1

I I REVIEW OF TUB LITERATURE 2

I I I EXPERIMENTAL 9

IV DISCUSSION OF RESULTS AND CONCLUSIONS 33

V STOIARY 36 V I BIBLIOGRAPHY 38

A il

LIST OF TABLES

I I D ata f o r C o n c e n tra tio n Curve (F ig u re 3) » • « 20

I I I D ata f o r C o n c e n tra tio n Curve (F ig u re 4) 22

I v

A, C o n c e n tra tio n Curve • • • • • • • • • 2 35* C olor S t a b i l i t y o f Antimony-Rhodarain© B Complex • • 2A6* E f f e c t of Acid C o n c e n tra tio n Upon O p tic a l D e n sity • • 26

7 , E f f e c t o f Io d id e C o n c e n tra tio n TJpon O p tic a l D e n sity * * 27

8 E f f e c t o f Rhodamine B C o n c e n tra tio n Upon O p tic a l

9* Polarograia© o f V ario u s Antimony S o lu tio n s • • • • 32

v

A method f o r th e d e te c t i o n and d e te rm in a tio n o f antim ony h as

been d ev elo p ed , b ased on th e e x t r a c t a b i l i t y o f antim ony ( I I I ) a s th e

io d id e i n t o benzene* The benzene e x t r a c t i® su b s e q u e n tly re a c te d w ith

an aqueous s o lu tio n o f Khodamine B, th e v i o l e t complex o f antim ony- Rhodamin© 8 fo r c in g in th e benzene l a y e r

As a s p o t t e s t f o r antim ony, th e p rocedure i s s p e c i f i c and

s e n s i t i v e P o t e n t i a l i n te r f e r e n c e s a re removed by c o n d itio n in g th e

t e s t s o lu tio n w ith sodium e u l f i t e and u r e a The t e s t c o n d itio n s a re

n o t c r i t i c a l * A com plete stu d y ©f in te r f e r e n c e s h as been made The

l i m i t of i d e n t i f i c a t i o n I s 0 2 microgram o f antim ony a t a c o n c e n tra tio n

l i m i t of Is 300,000

The sp ectro p h o to m © trie p ro c e d u re , based on th e same r e a c t i o n s ,

p e rm its th e d e te rm in a tio n of microgram q u a n t i t i e s o f antimony* The method I s p r a c t i c a l l y s p e c i f i c , bism uth i n t e r f e r i n g o n ly i f p r e s e n t I n

h ig h c o n c e n tr a tio n s An in te r f e r e n c e stu d y of th e same scope a s above

h a s been made The r e l a t i v e a n a ly s is e r r o r f o r te n micrograms o f a n t i ­

mony i s t 5*0$ Th3 c o n d itio n s o f a c i d i t y and re a g e n t c o n c e n tra tio n s have been s tu d ie d and have been shown to have wide ra n g e s o f t o le r a n c e The c o lo r formed i s s t a b le f o r a t l e a s t th r e e and o n e -h a lf h o u rs

A p o la ro g ra p h ic stu d y o f th e mechanism in d ic a te s t h a t antim ony

i s e x tr a c te d i n th e t r i v a l e n t s t a t e

v i

I n r e c e n t y e a rs th e d e te c t i o n and d e te rm in a tio n o f sm all amounts

o f antim ony h a s come to he a m a tte r o f c o n sid e ra b le p r a c t i c a l im portance* Antimony, which h as been known sin c e a t l e a s t 3000 B C , i s w id ely

d i s t r i b u t e d , b o th i n n a tu re and i n man-made products* Many th ousands

o f pounds o f i t go each y e a r i n to th e p ro d u c tio n o f h ard le a d (12% a n t i ­

mony), used in th e p ro d u c tio n o f sto ra g e b a t t e r i e s , b u l l e t s and sh rap n el#

I t i s an im p o rta n t c o n s titu e n t o f b e a rin g m etal and o f ty p e m e ta l, and

w id e ly used a s a pigment in th e p a in t and ru b b e r in d u s tr ie s * I t s com­pounds a re o f te n used In th e tre a tm e n t o f t r o p i c a l d i s e a s e s , th u s f r e ­

q u e n tly n e c e s s i t a t i n g i t s d e te rm in a tio n In b i o lo g i c a l samples*

D e sp ite th e s e f a c t s , th e tr a c e ch em istry o f antim ony h a s n ev er been

w e ll d ev elo p ed The w r i t e r , upon ob serv in g t h a t microgram q u a n t i t i e s o f antim ony ( I I I ) a s th e io d id e could be e x tr a c te d i n t o benzene, h a s c a r r i e d

o u t th e p r e s e n t stu d y i n an a tte m p t to a m e lio ra te t h i s s itu a tio n *

1

REVIEW OF THE LITERATURE

A v a r i e t y o f re a g e n ts have been proposed f o r th e d e te c tio n o f a n t i ­mony* E k k e rt (12) re p o rte d t h a t a la r g e number o f p h e n o ls, in c lu d in g

th e e r e s o l s , o r c i n o l , p h e n o l, p h lo r o g lu c in o l, and thym ol, g iv e c o lo r

r e a c tio n s w ith chloroform s o lu tio n s o f antim ony p e n ta c h lo rid e # G u tz e it (27) n o ted t h a t a n th ra ce n e r e a c te d w ith a s o lu tio n o f antimony t r i ­

c h lo r id e i n carbon t e t r a c h l o r i d e to g iv e a green c o lo r a ti o n , w hile

o f th e p r y o g a llo l t e s t f o r antimony* G a llic a c id was found by R o ssi and

S e re n te s (4-0) to be u s e f u l i n th e d e te c tio n o f antim ony i n th e p resen ce

o f b ism u th More r e c e n tly Wenger, D uckert and B lanc p a in (1 0 , 51, 52) have recommended fluoron© ( 9 - m eth y l-2, 3, 7 -trih y d ro x y ~ 6 -flu o ro n e ) a s a

s e n s i t iv e r e a g e n t f o r antim ony ( H I ) # At pH 4*0 th ey were a b le t o d e te c t

a s l i t t l e a s 0 2 microgram of antimony* They have a ls o e lu c id a te d th e

s t r u c tu r e o f th© compound form ed, and s tu d ie d th e i n te r f e r e n c e s which

o c c u r U n fo rtu n a te ly th© re a g e n t i s n o t s ta b le and i s e x ce ed in g ly d i f ­

f i c u l t t o p re p a re ; c a r e f u l c o n tr o l o f pH i s a c r i t i c a l p a r t o f th e p ro c e ­

d u re Oxine was observed by P i r t e a (39) to give a y ello w p r e c i p i t a t e

w ith a s l i t t l e a s tw elve raicrograms o f antimony t r i c h l o r i d e i n f iv e

2

m i l l i l i t e r s o f s o lu tio n , b u t th e procedure s u f f e r s from many I n t e r ­

fe re n c e s*

Ammonium d ithioearbam at© I s a s e n s i t iv e r e a g e n t f o r antim ony, ac­

c o rd in g to H e lle r and Macheck (2 9 ), b u t th e r e a re many i n t e r f e r i n g ions* The same was found t o be t r u e o f c y c lo h ex y leth y lam in ed iih io c arb a m a te by

Herrmann-Gur f i nfce 1 ( 3 0 ) , and by Dubsky and Nejevova (9)» Haiman (38)

used 2 -m eth y lb e n 2 0 th ia zo le a s a d rop r e a ©nt f o r antim ony, w h ile Dubsky, Okac and T r t l l e k ( 8 ) , found t h a t 2 , 5 -d im e rc a p to -1 , 3 , A -th io d ia z o le

c o u ld d e t e c t a s l i t t l e a s one microgrum o f antimony? a g a in th e r e were many i n t e r f e r e n c e s T hiourea was observed by Yoe and O v erh o lser (5 5 )

to g iv e a p a le yellow p r e c i p i t a t e , s u i t a b l e f o r th e d e te c tio n o f antim ony; some tw enty Io n s i n t e r f e r e d w ith t h e i r procedure*

C a ille and V ie l (1 ) d isc o v e re d th e r e a c t i o n , which now b e a rs t h e i r name, i n which antim ony ( I I I ) r e a c t s w ith a b a s ic n itro g e n o u s compound and p otassium io d id e to g iv e a yellow c o lo r o r p r e c i p i t a t e , s u i t a b l e f o r

tb e m ic ro sc o p ic a l d e te c tio n o f antimony* They in v e s tig a te d a la r g e

number o f n itro g e n o u s compounds a s r e a g e n ts , in c lu d in g q u in o lin e , a n t i -

p y r in e , p y r id in e , c in c h o n in e , e s p a r t i n e , m orphine, q u in in e , s tr y c h n in e ,

v e r a t r i n e , and cocaine* There a re many i n te r f e r e n c e s to t h e i r p ro c e d u re , bism uth b e in g among th e most s e r io u s M a rtin i (36) ad v o cated th e us© o f

c a f f e in e as th e n itro g e n o u s compound f o r t h i s p ro ce d u re,

A number o f lak e -fo rm in g d y e s tu f f s have been in v e s tig a te d a s p o ten ­

t i a l r e a g e n ts f o r antimony* Smith and Eogers (A3) proposed Bism ark Brown, Bordeaux Red, Hoffman V io le t 3R and p h e n o sa fra n in e , w hile Dubsky (7 ) used

g allocyanin© a s a reag en t* None of th e s e dyes proved t o be s a t i s f a c t o r i l y

s e n s i t i v e , a lth o u g h gallocyanin© was h ig h ly s e le c tiv e In a s tr o n g ly

a c i d ic medium* The f a m i li a r d y e s tu f f morin was observed by Goto (26)

“to g iv e an e x ce ed in g ly d e lic ti "be flu o re s c e n c e t e s t w ith antim ony ( I I I } ,

c ap a b le o f d e te c tin g a s l i t t l e as 0*05 m icrogram U n fo rtu n a te ly , as

i s t r u e w ith so many p ro ce d u res in v o lv in g f lu o r e s c e n c e , th e r e a r e many

io n s which i n te r f e r e *

Bhodamin® B, a xanthone dye s t u f f , was i n 1927 d isc o v e re d by

Eegriwe (1 1 ) t o r e a c t w ith solu tio n © o f p e n ta v a le n t antim ony, th e re d

c o lo r o f th e re a g e n t b ein g th e re b y changed t o v i o l e t o r b lu e , sometimes

w ith th© fo rm atio n o f a f i n e l y d iv id e d p r e c i p i t a t e The re a g e n t a s used

by Eegriw© was n o t s p e c i f i c , o r even s e l e c t i v e , a s i t could a ls o be used

f o r th e d e te c tio n o f b ism u th , c o b a lt, columbium, g o ld , manganese, m ercury, molybdenum, ta n ta lu m , th a lliu m , and tu n g sten * I t was, however, a h ig h ly

s e n s i t iv e r e a g e n t, e a s i l y p re p a re d , and s ta b le i n so lu tio n * 4 s su ch ,

i t was r a t h e r w id ely used a s a c o n firm a to ry t e s t f o r antim ony i n

sy s te m a tic schemes o f a n a ly s is (4 , 5, 4 7 ) W ith t h i s re a g e n t Eegriwe was a b le t o d e t e c t 0 ,5 microgram o f antim ony (V) i n th e p resen ce o f

even 12,500 tim es a s much t i n I n th© procedure employing aqueous media

F e ig l (16) ap p ea rs t o re g a rd o n ly f i v e test© f o r antim ony a s w orthy

o f mention* I n a d d itio n to th e Rhodamine B an^ fluoron© p ro c e d u re s , he

d e s c r ib e s th© t e s t by re d u c tio n to th e m e ta l, th© lum inescence t e s t , and

th e t e s t employing phosphomolybdic a c id a s a reag en t* The f i r s t o f

th e s e (17) has poor s e n s i t i v i t y ; th e l a t t e r two (6 , 22) a re of e x c e ll e n t

s e n s i t i v i t y , b u t s u f f e r from a la c k o f s e l e c ti v i ty *

S in c e th e appearance o f F elg l* a (16) book, on© good sp o t t e s t

procedure f o r antim ony h as a p p e a re d , namely th e one o f West and Conrad (5 4 ), which employs a s o l u t io n o f g o ssy p o l i n aceto n e a s a reag en t*

T h is pro ced u re i s v e ry s e n s i t i v e and h ig h ly s e l e c t i v e , b u t d oes have

c e r t a i n d isa d v a n ta g e s ; th e a c i d i t y o f th e t e s t s o lu tio n must be

c a r e f u l l y c o n tr o lle d and th e r e a g e n t i s no lo n g e r r e a d ily a v a ila b le *

Very r e c e n t l y H e in ric h (2d) h as in tro d u c e d an im p o rta n t m o d ifica ­

t i o n o f th e Rhodamin© B p ro c e d u re , i n which he e x t r a c t s antim ony (V) from 2 N h y d ro c h lo ric a c id s o lu tio n i n t o d i e t h y l e t h e r , th en r e a c t s th©

o th e r la y e r w ith an aqueous s o lu tio n o f Khodamlne B* T in , b ism u th ,

g o ld , th a lliu m , io d id e and th io c y a n s te I n t e r f e r e w ith th e procedure*

U n fo rtu n a te ly th© a v a ila b le methods f o r th e d e te rm in a tio n o f

microgram q u a n t i t i e s o f antim ony a re i n no b e t t e r s t a t e th a n ,th e means

f o r d e te c tin g them* Ho l e s s an a u th o r ity th an S a n d e ll (41) h a s s t a t e d

b l u n tl y t h a t * th e tr a c e ch em istry o f t h i s elem ent (antim ony) i s n o t w e ll-

d e fin e d * "

Bp to th e p a s t decade th e well-known io d id e r e a c tio n had f o r many

y e a rs formed th© b a s is f o r most c o lo r im e tr ic d e te rm in a tio n s o f t r a c e amounts o f antimony* In t h i s method (1 5 , 31, 37) antim ony ( I I I ) i n

s tr o n g ly a c i d ic s o lu tio n i s t r e a t e d w ith e x c e ss io d id e io n to form th e

h ig h ly c o lo re d (Yellow) potassium te tra io d o a n tlm o n a te ( I I I ) complex*

A sco rb ic a c id o r hypophosphite i s p re s e n t to reduce sm a ll amounts o f

f r e e io d in e which may be lib e r a te d * Many o x id iz in g a n io n s can i n te r f e r e * Bismuth g iv e s a s im ila r c o lo r , b u t I t s c o n tr ib u tio n t o th e o p t i c a l den­

s i t y can be s u b tra c te d i f a re a g e n t o f a c e r t a i n potassium io d id e

c o n c e n tr a tio n i s used* The r e a c t i o n i s c a r r ie d o u t i n 10% s u l f u r i c

a c id s o lu tio n *

C lark e (2 ) and o th e r s (1 4 , 42) have used th e golden y ello w c o lo r

formed w ith p y rid in e and an io d id e i n a cid s o lu tio n f o r th e d e te rm in a ­

t i o n o f antimony* The optimum c o lo r developm ent o c cu rs in 1*3 s u l f u r i c

a d d * The c o n c e n tra tio n o f io d id e and o f p y rid in e a r e c r i t i c a l * F a i r l y

sm a ll amounts o f a r s e n ic and t i n do n o t i n te r f e r e * b u t b ism u th , s in e

and s e v e r a l o th e r m e ta ls g iv e c o lo re d p r e c i p it a te s * Any p a n ta v a le n t antimony

p r e s e n t i s reduced t o th© t r i v a l e n t form , which r e a c ts * S u lfu ro u s a c id

i s added to th e re a g e n t to red u ce any fra© io d in e which n ig h t be

l i b e r a t e d Gum a r a b le i s used to keep th e complex formed i n suspension*

V a s ile v and Shub (4$) have m odified th e p y r id in e - io d id e pro ced u re

by e x tr a c t i n g th© developed c o lo r i n t o amyl alco h o l* T his s te p I n c r e a s e s

th e s e n s i t i v i t y o f th e method*

An o ld method (1 3 ) f o r th© e s tim a tio n o f antim ony u t i l i s e d a c o l­

l o i d a l su sp en sio n o f th e o ra n g e -c o lo re d s u lfid e * Any p en ta v a le n t antim ony was reduced b efo reh an d w ith s u l f u r dioxide* T h is method gave f a i r ac­

c u ra c y , b u t on ly i f a l l o th e r m e ta llic c o n s titu e n ts had been removed

p r i o r to th e d ete rm in a tio n * Gum a r a b le was u sed to s t a b i l i s e th e su s­

pended s u lfid e *

The f a m i li a r molybdenum blu© r e a c tio n has been a p p lie d to th e

d e te rm in a tio n o f antim ony (3 2 ), th© r e a c tio n b ein g t h a t o f antiraonous

io n on phosphontolybdic acid * I r o n , copper and t i n i n t e r f e r e i f p r e s e n t

i n sm all amounts* The pH o f th© system r e q u ir e s c a r e f u l c o n tr o l

The r e a c tio n o f t r i v a l e n t antim ony w ith phosphom olyM otungstlc a c id

h as a ls o been used f o r i t s c o lo r im e tr ic e s tim a tio n ( 3 4 )

I n th e absence of a r s e n i c , antim ony may be evolved a s s t l b i n e and

e s tim a te d by th e I n t e n s i t y o f th e s t a i n formed on m ercu ric c h lo r id e

p ap er (3 )* T his method has been w id ely u se d ,

F re d e ric k (2A) was a p p a r e n tly th e f i r s t to u t i l i z e Khodamlne B

a s a re a g e n t f o r th e d e te rm in a tio n o f antimony* H is procedure i n ­

v olved c o o lin g th e r e a c te d system to below 10° 0*, a t which p o in t th e antimony-Khodamine B complex was in s o lu b le , and d e s tro y in g th e e x c e ss

r e a g e n t w ith brom ine T h is was a c r i t i c a l o p e ra tio n The complex was

th e n d is s o lv e d i n a lc o h o l f o r th e c o lo r im e tr ic e s tim a tio n A c a r e f u l l y

d eterm in ed b lan k was e s s e n t i a l , and th e method re q u ire d an e x p erien c ed

o p e r a to r , a s "ab o u t 1$ o f a l l a n aly se s" f a i l e d i n F r e d e r ic k 's hands#

W ebster and F a i r h a l l (49) p rovided a c o n sid e ra b le advance o v er

F r e d e r ic k 's work by in tro d u c in g th e u se o f benzene to e x t r a c t th e m e ta l- dye complex a f t e r i t s fo rm atio n i n th e aqueous s o l u t io n , th u s sh o rte n in g

th e p rocedure and making i t c o n s id e ra b ly more r e l i a b l e #

Maren (35) u t i l i z e d th© work o f W ebster and F a i r h a l l (49) I n de­

v e lo p in g h i s procedure f o r th e d e te rm in a tio n o f antimony i n b i o lo g i c a l

t i s s u e s I n a d d itio n , he proposed an Im p o rtan t a l t e r n a t i v e method

w h erein antim ony, i n th© p e n ta v a le n t s t a t e , i s e x tr a c te d I n to Iso p ro p y l

e t h e r , The e th e r la y e r i3 removed and shaken w ith an aqueous s o lu tio n

o f Rhod&mine D, whereupon th e c o lo re d complex i s developed In th e e t h e r , and measured p h o to m e tric a lly * I n Iso p ro p y l e th e r th e complex does n o t obey B e e r’s Law, and th e c o lo r i s n o t s ta b le f o r more than t h i r t y

m in u te s, b u t th e e x tr a c tio n procedure a id s m a te r ia lly In g a in in g s p e c i­

f i c i t y * Maren s tu d ie d on ly e le v en m etals a s p o te n tia l i n t e r f e r e n c e s

At 1 m illig ra m a r s e n ic , t i n and ir o n i n t e r f e r e d The i n te r f e r e n c e o f

i r o n was e lim in a te d by u sin g th e e th e r method#

Th© pro ced u re of Maren h as been s tu d ie d by Freeman ( 2 3 ) , who noted

t h a t th© c o n c e n tra tio n o f s u l f u r i c a c id i n th© s o lu tio n t o be e x tr a c te d

e x e r te d a marked e f f e c t on th e c o lo r i n t e n s i t y o f th e r e s u l t a n t e x tr a c t*

G elh o m and o th e r s (25) have a p p lie d th e method o f Maren to th e e stim a ­

t io n o f antim ony i n c l i n i c a l work*

E O T R IM Sm i*

I* M a te ria ls and A pparatus

0*1000 gram o f m e t a l l ic antim ony (OP g ra d e , B aker and Adamson) was

c a r e f u l l y w eighed, d is s o lv e d i n 25 m i l l i l i t e r s o f h o t c o n c e n tra te d s u l­

f u r i c a c id , allow ed t o c o o l, and d i lu t e d t o 100 m i l l i l i t e r s w ith water#

I t was th en made up to one l i t e r w ith I s 3 s u l f u r i c acid* More d i l u t e sta n d a rd s were made up from t h i s s o lu tio n by p i p e t t in g th e a p p ro p ria te volumes i n t o 100 m i l l i l i t e r v o lu m e tric f l a s k s and d i l u t i n g to volume w ith

1 :3 s u l f u r i c acid * These a re th© s ta n d a rd s recommended by S n e ll and

S n e ll (4 4 ) f o r th e c o lo r im e tr ic d e te rm in a tio n o f antim ony

10$ potassiu m io d id e s o lu tio n was p rep ared by d is s o lv in g 10 grams

o f th e CP s a l t and d i l u t i n g t o 100 m i l l i l i t e r s w ith water*

CP benzene was used w ith o u t f a r t h e r p u r if ic a tio n *

1 :3 s u l f u r i c a d d was p rep ared by d i l u t i o n o f th© c o n c e n tra te d GP

s h e l f re a g e n t w ith th e a p p ro p ria te volume o f w ater#

Th© Bhodamine B s o l u t lo was p rep ared by d is s o lv in g 0.2 0 0 grams

o f th e d y e s tu f f i n w a te r and d i lu t i n g t o 100 m i l l i l i t e r s w ith w ater*

T h is s o lu tio n was f i l t e r e d b e fo re using*

C a lib r a te d w eig h ts and v o lu m e tric g lassw are were used th ro u g h o u t

th e work#

A Beckman Model B sp e ctro p h o to m e ter was used f o r th e g r e a t e r p a r t

o f th e work d e sc rib e d h erein #

A Beckman Model DU sp e ctro p h o to m e ter was used t o check c r i t i c a l

p o in ts In th e work* The same Corex c e l l s , o f 1*00 c e n tim e te r p a th le n g th , were used i n b o th in stru m en ts#

9

A S a rg e n t Mortal XU p o la r ograph was used i n th e p o la ro g ra p h ic stu d y

o f th e mechanism o f th e e x t r a c t i o n , A Bausoh and Lonb la r g e L i t trow

sp e c tro g ra p h wa® used i n th e sp e c tro g ra p h !^ su rv ey o f th e e x tr a c t i o n

I I The S p o t T e s t D e te c tio n o f Antimony

In th e co u rse o f a se arc h f o r a s u i t a b l e s o lv e n t f o r th e e x tr a c tio n

o f th e p o tassiu m te tra d o d o a n t imoneite ( I I I ) complex, th e a u th o r observed

t h a t th e stro n g yellow c o lo r o f th© complex d isa p p e a re d when aqueous ( a c i d ic ) s o lu tio n s o f i t were shaken w ith b en zen e Upon removing the benzene la y e r and shaking I t w ith an aqueous s o lu tio n o f Rhodamine B,

th e v io le t - c o l o r e d complex o f antimony-Rhodamine B was observed t o form

i n th e b en zen e T h is was o b v io u sly a r e a c tio n w e ll w orth f u r t h e r stu d y , from b o th a q u a l i t a t i v e and a q u a n ti t a t iv e s ta n d p o in t

The i n i t i a l t e s t s o lu tio n was one o f antimony t r i c h l o r i d e i n X N

h y d ro c h lo ric a c id , p rep ared so a s to give a c o n c e n tra tio n o f f iv e

raicrograms o f antim ony ( I I I ) p e r d ro p One d ro p o f t h i s s o lu tio n was

d i lu t e d i n a t e s t tube with, f iv e d ro p s o f 1 H h y d ro c h lo ric a c id , a drop

o f 10$ potassium io d id e s o lu tio n was added, and th e aqueous s o lu tio n was

th e n e x tr a c te d by v ig o ro u s ly sh ak in g w ith one m i l l i l i t e r of benzene.Upon shaking th e yellow c o lo r o f th e KSbl^ complex was observed t o d i s ­

a p p e a r The benzene la y e r was then removed w ith a pd p et and p u t i n to a second t e s t tu b e To t h i s tube was added a drop o f a 0,2% aqueous so lu ­

t io n o f Rhodamine B, and th e tu b e was then v ig o ro u sly shaken* The

c h a r a c t e r i s t i c v i o l e t hue o f th© antimony-Rhodamln© B complex was

seen to ap p ear a t once In th e benzene l a y e r A b lan k o f one drop o f

IN HOI, t r e a t e d s i m il a r ly , produced no c o lo r in th e benzene l a y e r

A stu d y o f th e l i m i t o f i d e n t i f i c a t i o n o f t h i s procedure I n d ic a te d

t h a t a s l i t t l e a s 0 2 microgram o f antim ony could be d e te c te d An i n ­

te r f e r e n c e stu d y was th en begun; th e f i r s t compound t e s t e d , sodium

n i t r a t e , im p arted to th e benzene la y e r a s tr o n g ly f lu o r e s c e n t b lu is h

c o lo r , which co m p letely masked th e t e s t c o lo r As sodium c h lo r id e

d is p la y e d no such b e h a v io r, i t was obvious t h a t n i t r a t e was th e i n t e r ­

f e r in g io n T h is was most s e r i o u s , i n view o f th© w idespread o ccu rren ce

o f n i t r a t e

An obvious method o f a tt a c k was to remove th e n i t r a t e by adding

s u l f u r i c a c id and b o ilin g down t o fumes o f s u l f u r t r i o x i d e , b u t th©

v o l a t i l i t y o f antim ony t r i c h l o r i d e p reclu d ed t h i s s t e p The a d d itio n

o f a p r e c i p i t a n t f o r n i t r a t e , such a s N itro n , would have made th e pro ­ced u re to o cumbersome

Every p r i o r i n v e s t i g a t o r o f th e antimony-Ehodamine B r e a c t i o n had

re p o rte d th e p resen ce o f a la r g e c o n c e n tra tio n o f c h lo rid e io n a s ab­

s o l u t e l y e s s e n t i a l to th e fo rm atio n o f th© complex The w r i t e r , i n

th e hope t h a t io d id e m ight serv e a s an a c c e p ta b le s u b s t i t u t e f o r

c h lo r i d e , p re p a re d s ta n d a rd s o f ( m e ta llic ) antim ony i n 1*3 s u l f u r i c

a c i d To on© d ro p o f such a s ta n d a rd , c o n ta in in g te n micrograms o f

antim ony ( I I I ) , were added f i v e dro p s o f 1*3 s u l f u r i c a c id and one drop

o f 10$ p o tassiu m io d id e* The s o lu tio n was th en e x tr a c te d w ith on©

m i l l i l i t e r o f b en zen e, w ith v ig o ro u s sh ak in g The benzene la y e r was

removed and to i t was added on© drop o f th e 0.2% aqueous Rhodarain© B s o lu ­

t i o n Upon sh a k in g , th e c o lo r o f th© antimony-Hhodamine B complex

ap p eared i n th e benzene, d e s p ite th e f a c t t h a t c h lo rid e io n had been nowhere p r e s e n t i n th e p ro c e d u re

I t was th e n a sim ple m a tte r to remove th e i n t e r f e r i n g n i t r a t e

by h e a tin g th e t e s t s o lu tio n to fumes o f s u l f u r t r i o x i d e , adding

w a te r to re g a in ap p ro x im ately th e i n i t i a l volume, and p ro ceed in g a s

above w ith th e a d d itio n o f th e potassium io d id e and su b seq u en t step s*

l a t e r i t was found t h a t th e in te r f e r e n c e a s c r ib e d t o n i t r a t e

co u ld be more e x p e d itio u s ly removed by th e a d d itio n o f a few m i l l i ­

grams o f s o l i d u re a to th e t e s t so lu tio n * Inasmuch a s u rea i s known

to red u ce n i t r i t e s b u t n o t n i t r a t e s , t h i s makes i t a p p ea r l i k e l y t h a t

th e in te r f e r e n c e was due to th e sm a ll amount o f n i t r i t e p re s e n t a s an

im p u rity i n n i t r a t e s * The a d d itio n o f u re a was a ls o co m p letely e f ­

f e c t i v e i n removing th e i n te r f e r e n c e due to n i t r i t e a s such*

i s a n t i c i p a t e d , s tro n g o x id is in g a g e n ts such a s perm anganate and brornate i n t e r f e r e d w ith th e p ro c e d u re , a s d e sc rib e d above, by th e

l i b e r a t i o n o f f r e e io d in e* Upon e x tr a c tio n th© benzene la y e r was so

h ig h ly c o lo re d by th e io d in e t h a t th e t e s t c o lo r was co m p letely masked*

T h is d i f f i c u l t y was circum vented by a llo w in g th e o x id a tio n o f io d id e

t o proceed t o c o m p letio n , and th en su b seq u e n tly red u cin g th e l i b e r a t e d

io d in e w ith an ex ce ss o f sodium s u l f i t e b e fo re p ro ceed in g w ith th e

e x tr a c t i o n and c o lo r development*

I n i t i a l l y th e t e s t c o lo r was viewed by h o ld in g th e t e s t tube con­

t a i n i n g th e ben zene-Khoda mine B a g a in s t a w h ite background, and com­

p a rin g i t w ith a b la n k t r e a t e d s im ila rly * Using t h i s method I t was

d i f f i c u l t f o r an in e x p e rie n c e d o p e ra to r t o d e te c t antim ony i n v e ry low

c o n c e n tra tio n s * T h erefo re th© w r i t e r m odified th e p ro ce d u re, p i p e t t in g

th e benzene e x t r a c t d i r e c t l y i n t o th© d e p re ss io n o f a whit© s p o t p l a t e , and c a r e f u l l y adding to i t th e drop o f aqueous reag en t* The r e a g e n t drop

rem ained I n t a c t i n th e c e n te r o f th e d e p re s s io n , and th e complex could

be seen d if f u s in g i n t o th e benzene l a y e r , i t s c o lo r c o n tr a s tin g sh a rp ly

w ith th e whit© background* T h is p ro v id e s a v e ry s t r i k i n g and e f f e c t i v e

d e m o n stra tio n o f th e s p o t t e s t method o f a n a ly s is *

Th© s p o t t e s t p ro ce d u re, a s f i n a l l y d e v elo p ed , i s a s fo llo w ss

one d ro p o f th e t e s t s o lu tio n i s p lac ed i n a t e s t tu b e , f iv e d ro p s o f

I t 3 s u l f u r i c a c id and on© d rop o f 10$ potassium io d id e a r e added,

follow ed by a few m illig ra m s o f s o l i d urea* I f f r e e io d in e a p p e a rs to

be l i b e r a t e d , s o l i d sodium s u l f i t e should b© added u n t i l th e c o lo r i s

d isch arg ed * Th© s o lu tio n i s th e n e x tr a c te d by shaking v ig o ro u s ly w ith

one m i l l i l i t e r o f benzene* The benzene l a y e r i s removed w ith a p i p e t

and p la c e d i n th e d e p re ss io n o f a w hite s p o t p l a t e , i n th e c e n te r o f

which a d ro p o f 0*2$ aqueous Bhodamine B i s th e n placed* I n t e r p r e t a t i o n

o f th© t e s t , based on th e appearance o f th e v i o l e t complex i n th© ben­ zen e, l a mad© w ith in te n seconds* The b la n k w i l l have o n ly a v e ry f a i n t

p in k is h hue*

A sy s te m a tic stu d y o f i n te r f e r e n c e s to t h i s procedure was made,

a f t e r th e manner su g g ested by West (53)* Th© io n s s tu d ie d were p re s e n t

In & c o n c e n tra tio n r a t i o o f 1000 micrograms o f th© io n t o 10 micrograms

o f antim ony The io n s s tu d ie d a r e shown in T able I Wo in te r f e r e n c e s were found a t t h i s r a tio * I t was found t h a t b ism u th , a t 1000 m icro - gram s, gave a t e s t c o lo r t h a t m ight have been m istak en f o r antim ony

a t 0*2 micrograms*

Th© d e te rm in a tio n o f th e l i m i t of i d e n t i f i c a t i o n and c o n c e n tra tio n

l i m i t o f th e procedure was c a r r i e d o u t in the manner p re s c rib e d by

F© igl (18)* They a re a s follow s?

TABLE I

Scope of In te rfe re n c e S tu d ie s

LI / Be & BOa - COj •**' w * / F - Fa 44 CN

L im it o f I d e n t i f ic a t i o n s 0 2 microgram o f antim ony

C o n cen tratio n L im it: 1:300,000

The e f f e c t s of changing th e r e a c tio n c o n d itio n s were s tu d ie d , Mid

i t was found t h a t n e it h e r th e a c id c o n c e n tr a tio n , nor th e io d id e con­

c e n t r a t i o n , nor th© re a g e n t c o n c e n tra tio n a re In any way c r i t i c a l *

The p ro ced u re was c a r r i e d o u t in c o n c e n tr a tio n s o f s u l f u r i c a c id

v a ry in g from 4- N (1 :8 ) to 18 H (1 :1 ) w ith o u t a d v e rs e ly a f f e c t i n g th e

s e n s i t i v i t y A t h ig h e r a c id c o n c e n tr a tio n s th e a l r - o x i d a t l on o f th e

a c i d ic io d id e s o lu tio n I s g r e a t ly a c c e le r a te d , however, and i f i t i s

d e s ir e d to e lim in a te th e a d d itio n o f s u l f i t e th© a c i d i t y should be k e p t below 12 N I f th e a c i d i t y f a l l s much below 4 N th e s e n s i t i v i t y o f th e procedure I s dim inished#

The c o n c e n tra tio n o f th e potassium io d id e s o lu tio n added was

v a r ie d from 2% t o 20$, In in crem en ts o f 2%, w ith o u t d e c re a s in g th e

s e n s i t i v i t y H igher c o n c e n tra tio n s of th e io d id e a re o f co u rse l e s s

s t a b l e , and a re l e s s co n v en ien t on t h a t a c c o u n t

Rhodamine B c o n c e n tra tio n s o f 0.02%, 0.05%, 0.1%, and 0.5% were

t e s t e d Ho e f f e c t on th e s e n s i t i v i t y o f th© procedure was o b se rv e d

I I I The S p e c tro p h o to m e tric D eterm in atio n o f Antimony

The sta n d a rd s o lu tio n s o f antim ony i n I s 3 s u l f u r i c a c id , d e sc rib e d above, were used th ro u g h o u t t h i s phase o f th e work, e x c e p t a s n o te d i n th© second p arag rap h below

To one m i l l i l i t e r o f a s o lu tio n c o n ta in in g 10 micrograms o f a n t i ­mony was added 0 1 m i l l i l i t e r o f 10% potassium io d id e T h is s o lu tio n was s u c c e s s iv e ly e x tr a c te d w ith th r e e 1 5 ml 11I I i t e r p o rtio n s of benzene The benzene e x t r a c t s were removed by p i p e t and combined, and t o them was

added 0 1 m i l l i l i t e r of' a 0.2% aqueous s o lu tio n o f Rhodamine B« A f te r tho ro u g h shaking th e c o lo re d benzene l a y e r ms removed from th e re a g e n t; com plete rem oval was in su re d by washing th e re a g e n t w ith two 1 5 m il: i~

l i t e r p o rtio n s o f b en zen e The combined c o lo re d benzene l a y e r and

w ashings were p la c e d d i r e c t l y i n a 10 m i l l i l i t e r v o lu m e tric f l a s k , and

th e s o lu tio n was d i lu t e d to th e mark w ith benzene The a b s o rp tio n

spectrum o f th e benzene s o lu tio n was th e n o b serv ed , u sin g a Beckman Model DU sp e c tro p h o to m e te r The curve i s shown in F ig u re 1 (A)

To one m i l l i l i t e r o f a s o lu tio n c o n ta in in g 20 micrograms o f an* tim ony, a s th e t r i c h l o r i d e , i n c o n c e n tra te d h; d r o c h lo r ic a c id , was

added on© drop of 10% sodium n i t r i t e s o lu tio n , t o o x id iz e th e antim ony

t o th© p e n ta v a le n t s t a t e , T his s o lu tio n was warmed f o r f iv e m in u tes

to d e s tr o y th e n i t r i t e , was c o o le d , and 0 ,1 m i l l i l i t e r o f 0,2% aqueous Rhodamine B s o lu tio n was added, The antlmony-Ehodamine B complex was

th en e x tr a c te d from th© s o lu tio n by shaking w ith th r e e su c c e ss iv e two

m i l l i l i t e r portion© of benzene, Th© e x t r a c t s were combined and p lac ed

i n a te n m i l l i l i t e r v o lu m e tric f l a s k , th en d i lu t e d to th e mark w ith

b en z?n e The a b s o rp tio n spectrum o f t h i s s o lu tio n was th en o b serv ed ,

u sin g a Beckman Model DU s p e c tr e hotom eter* The r e s u l t a n t curve i s shown i n F ig u re 1 , (B)

To t e s t th e co n fo rm ity o f th e c o lo re d complex t o Beer*® Law, Hie procedure was a p p lie d t o fo u r s o lu tio n s o f w idely v a ry in g antim ony

c o n c e n tr a tio n One m i l l i l i t e r volumes o f s o lu tio n s c o n ta in in g 5, 10,

2 0 , and 4-0 mlcr©grams o f antim ony p e r m i l l i l i t e r were d e liv e r e d from a

c a l ib r a t e d p ip e t i n t o t e s t tu b e s To each was added 0 ,1 m i l l i l i t e r o f 10% p otassium io d id e The s o lu tio n s were th en shaken v ig o ro u s ly w ith

c o lo re d benzene la y e r s removed, th e re a g e n t cashed w ith two 1*5 m i l l i ­

l i t e r p o r tio n s o f ben zen e, and th e combined w ashings and c o lo re d

benzene l a y e r s were p u t i n t o 10 m i l l i l i t e r v o lu m e tric f l a s k s and d i lu t e d

t o th e mark w ith benzene* A b so rp tio n s p e c tr a were th en observed f o r

th e s e fo u r so lu tio n ® , u sin g a Beckman Model B sp e c tro p h o to m e te r The

r e s u l t a n t c u rv e s a re shown i n F ig u re 2

Inasmuch a® th e r a t h e r sh arp a b s o rp tio n maximum a t 560 m illim ic ro n s

d id n o t s h i f t o r d im in ish i n i n t e n s i t y w ith v a ry in g antim ony c o n ce n tra ­

t i o n , th e r e l a t i o n s h i p o f o p t i c a l d e n s ity to c o n c e n tra tio n was in v e s ­

t i g a t e d o v er a range o f c o n c e n tr a tio n s The procedure employed was th e same a s t h a t d e sc rib e d im m ediately above The r e s u l t a n t cu rv es a re shown

i n F ig u re s 3 -4 Data f o r th e s e corves a re given i n T ab les I I - I I I

The e f f e c t o f v a r i a ti o n o f c o n d itio n s upon th e p rocedure was n e x t

in v e s tig a te d * The p ro ced u res employed i n th e e x tr a c tio n and c o lo r

developm ent were th e same a s th o se d e sc rib e d above

The s t a b i l i t y o f th e c o lo r o f th e complex, a t a c o n c e n tra tio n

o f 10 microgrsme o f antimony p e r m i l l i l i t e r , was observed o v er a

p e rio d o f 3 5 h o u rs The c o lo r was found to be a lto g e th e r s ta b le d u rin g

t h i s period* The same s o lu tio n examined te n h o u rs l a t e r , was found to have d e c re a se d i n i n t e n s i t y o n ly s l i g h t l y The r e s u l t s a re shorn i n

F ig u re 5

The e f f e c t o f v a ry in g th e a c i d i t y o f th e sample wa@ s tu d ie d by

p re p a rin g s o lu tio n s c o n ta in in g 10 micrograms o f antimony i n s u l f u r i c a c id