Some spectral and chemical interferences on the determination of dysprosium, holmium and erbium by
atomic absorption spectrophotometry
by Hans Christian Claassen
A thesis submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree of
MASTER OF SCIEHCE in Chemistry
Montana State University
© Copyright by Hans Christian Claassen (1964)
Abstract:
The spectral and chemical interference of the rare earth elements, and those elements in common
association with rare earth ores upon perchloric acid dissolution, on the determination of dysprosium,
holmium and erbium by atomic absorption spectrophotometry is reported. Some suggestions are made
to aid the analyst in determining these rare earths in the presence of other rare earths A redox
phenomenon based on electronic configuration is suggested to explain the rare earth element
interference observed. This is believed to be a new approach to flame processes involving the rare earth
elements. SOME SPECTfiAL AHD CHEMICAL IMTEBFEBEHCES OH THE DETEfiMIHATIOH
CF DTSPEOSIUMy EOLMIUM AHD EfiBIUM DY ATOMIC
ABSOfiPTIOH SPECTBOPHOTCHETHr
Dy
HAHS Co CLAASSEH
A t h e s i s subm itted t o th e G raduate F a c u lty i n 'p a r t i a l
f u l f il l m e n t of th e req u irem en ts f o r th e degree
of
MASTER CF SCIEHCE.
in
Chemistry
Hehds Maj oryD^partment
l^ D e a n 9 G raduate D iv is ibn"
MOHTAHA STATE COLLEGE
Bozeman9 Montana
Angust9 1964
AGKETOWLBDOIBNT
I would l i k e to th an k D rs» R9 Woodxiff and K9. Snexson and
a ls o Mx9 He McLean f o r t h e i r su g g e stio n s apd a ssista n c e *
To my w ife C h ris tin e , my g r a titu d e f o r h e r p a tie n c e and
coopera t i an*
iv
TABLE GF COETEEDS
LIST G®1 TABLES
Page
o e ® e e o o o ® o e ® e e e e e » o e » » e . o e » e » o o e o e e o o » e < »
IlIST QF FIGfCJEES e e e e o o » e ®o ®e # e * e ®®®e o o ®o e e o e e e e » » e e o o e
ABSTRACT ©«®* 0 ®®'0 ®0 . ®« 0
Ho
IIIo
Vo
V ie
0
®0
0 0
®0
0
®®0 ®0 « 0 ®0
0
®0 »®®<»0
0 0 9
(»
Tl i
I ETEODU CTIOE -o o e e o o o o e d o o o o e o o o e o o e.o. Ad e o ^ e o e o o o o e e o y e *
1
GfEETERAL COESIDEEATIOES <>o o » e,.o ®e.
2
*»oeo®ooo *, # o ««
EXPERIMEETAXi oooo. oooo o, o«»oooo®oooo0. ®o®ooooo® oop!ooooo eo©
Ao
33o
Co
3D*
IVo
®0
Vl
RESULTS
A bsorption Apparatus
In stru m e n ta l Oonixtxons eeeo»000**0***00*000
A bsorptxon P ro o e iu re s oo»o*»»oeo»oe»oooe-»*oe
Standard S o lu tx ons eo***»*ooo*ooo*ooo*ooo*oo
0 0 9 0 0 0 . 0 0
0 0 0 0 e «
0 0 9 0 0 0 0 0 0 * 0 0
O O
0. O O O O
0 0 9 0 0 0 0 0 0 0
O O O O O O O O O O O O O O O O O O O O O O O O O O
Ao
S p Q c i j I kQ l
Bq
CllGnH C©I ■!n 't Gicf GIPGHOGS Oe o o o e o g o e o e o o o o o e o o o
Co
DO
AzisIyt ZLCsI P 0"t©Zl*fcl s i 90090000,Ooooooooeoooooo
Da t S o o o o o o o o o o o o o o e o o o e o o o o o o o o o o o o o o o o o o o ©
SQlMAKr
O '0 0 0 9 0 0 0 0
I 1T T E R A T TiI - b E
C IT E S
-4 -4 Vn
Io
0
V
In * fc 6 3 ^ f © 3?© H C G S
o o o o o a o o o o o o o o o o o o o o o
9
II
is
17
O '0 0 0 0 0 0 0 0 0 0 9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9 0 0 0 0 9 0 0 0 0 0
22
o o o o o e o o o o o o o o o o o o o o o o o o o e o o o o o o o o o o o
24
T
LIST OF TABLES
T able
.
Ie
Optimum In stru m e n ta l C onditions
He
IIIe
IVe
Page
»o . eo.,»»«, <,»«,«
7
S p e c tra l I n te r f e r e n c e s on Dysprosium9 Holmitmv and
Erbium i n U n its of P ercen t T ran sm ittan ce »,»„«, O00e6
10
Chemical In te r f e r e n c e s of Non Bare E arth M e tals' oh"
Dysprosium, Holmium and Erbium ooeoe o.«oooooooeoe60e
12
Chpmical I n te r f e r e n c e s of Bare E a rth Elements on
Dysprosium, Holmium and Erbium e oeoeeeoeeeeeeeoeee.e
13
vi
LIST CF FIGUBBS
F ig u re
Page
I0
L a st Stage Tuned A m plifier
2«
E f f e c t o f B are E a r th I n t e r f e r e n t s on t h e A b so rb a n c e '"
o f 200 u g it/m l E rbium #**@*@*@»****@»@**#@@****@**@@*0
14
E ffe c t of" V arying Amounts of I n t e r f e r e n t on
250 Ugm/ml Dysprosium o e e e e e e e e e e e e e e e e e e e e e e e o e e e e . e»
18
E ffe c t of V arying Amounts of I n t e r f e r e n t on
300 Ugm/ml HolmiUm eeeooeo#o*e»*o»o*oo#*eeeeoe*eeoeee
18
E ffe c t o f V arying Amounts of I n t e r f e r e n t oh
200 Ugm/ml E rbium o o c e o e e e o e o c o e o e e e e e e e e e e e e o e e e o e e e
19
E ffe c t of 1000 ugm/ml I n t e r f e r e n t on V arying
C on cen tratio n s o f Dysprosium ee; ®».»<,««»»»„.e «.e
20
3«
4«
5»
6«
6 e O O 0 » O 0,0
0 0 0 0 0 0 0 0 0 0 0 0 9 0 0 0 0
7«
E ffe c t of 1000 ugm/ml I n t e r f e r e n t on V arying'
C o n cen tratio n s of Holmium
8®
E ffe c t of 1000 ugm/ml I n t e r f e r e n t on V arying
»c eo
C o n o e n tr a tr ons o f Erbium ®@®eo®*®®®®®®®®®®®®®*®®®®®®®
6
v ii
ABSTRACT
The s p e c tr a l and chem ical i n te r f e r e n c e of th e r a r e e a rth
elem en ts, and thbsje elem ents i n common a s s o c ia tio n m t h r a r e
eaJrth o res upon p e rc h lo ric a c id d is s o lu tio n , on th e determ in­
a tio n of dysprosium , holmium and erbium by atom ic a b so rp tio n
sp ectro p h otom etry i s rep o rte d * Some su g g e stio n s a re made t o
a id th e a n a ly s t i n d e te rm in in g th e s e r a r e e a rth s i n th e p resence
of o th e r ra re , e a rth s e
A redox phenomenon based on e le c tr o n ic c o n fig u ra tio n i s
su g g ested t o e x p la in th e r a r e e a r th elem ent in te r f e r e n c e
observed* T his i s b e lie v e d to be a new approach t o flam e
p ro c e sse s in v o lv in g th e r a r e e a rth elem ents* .
IBTRaDUCTIOIT
I t has been dem onstrated ( 19) t h a t a t l e a s t some of th e
r a r e e a r th elem ents can be a n a l y ti c a l ly determ ined by means of
atom ic a b so rp tio n sp ectro p h o to m etry .
I t i s fu rth erm o re e v id e n t
t h a t sin c e th e r a r e e a r th elem ents a re chem ically s im ila r ( 20,
21, 26) th e y w i l l of n e c e s s ity be determ ined i n p resen ce of each
o th e r , and a stu d y of th e s p e c tr a l and chem ical ( c a tio n ic )
in te r f e r e n c e s w ill be n e c e ssa ry .
H is to r ic a lly , t h e r e has been much s p e c u la tio n as t o flam e
p ro c e sse s governing observed chem ical in te r f e r e n c e s ,
Most
in v e s tig a to r s have proposed th e fo rm a tio n of r e f r a c to r y com­
pounds to e x p la in th e observed i n te r f e r e n c e (1 8 ,2 4 ,2 5 ),
I n th e
d e te rm in a tio n of m etals which form r e f r a c t o r y o x id es, such as th e
r a r e e a r th s , few m etal atoms a re a v a ila b le f o r a b so rp tio n or
em issio n ,
A f u e l - r i c h o zy g en /acety len e flam e has been su ccess­
f u l l y used i n lo w erin g th e d e te c tio n l i m i t s of r a r e e a r th elem ents
by b o th atom ic a b so rp tio n ( 19) and em ission (3 ,7 ) spectrophotom etry
T his method owes i t s su c ce ss to th e proposed ( 7) r e a c tio n
REO * C = RE0 + CO
...........
(I)
Though t h i s r e a c tio n i s s u f f i c i e n t t o e x p la in th e in c re a s e d
a b so rp tio n (o r em ission) when only one r a r e e a rth elem ent i s
p r e s e n t, i t becomes in ad e q u ate when o th e r r a r e e a rth elem ents
a re in tro d u c e d .
GfEBTERAL CONSIDERATIONS
The prim ary o b je c tiv e i s t o p re s e n t em p iric a l evidence
of s p e c tr a l and chem ical in te r f e r e n c e s of r a r e e a rth elem ents i n
th e d e te rm in a tio n of dysprosium , holmium and erbium by atom ic
a b so rp tio n m ethods.
I n a d d itio n , chem ical and s p e c tr a l i n t e r ­
fe re n c e d a ta w i l l be given on th o se elem ents which a re l i k e l y
to occur w ith r a r e e a r th elem ents upon d is s o lu tio n of t h e i r ores
w ith p e r c h lo r ic a c i d \
I t i s expected th a t th e s p e c tr a l in te r f e r e n c e observed w ill
be a fu n c tio n of th e e f f e c t i v e bandw idth of th e monochromator (5 )
and any l i n e s .or bands of th e i n t e r f e r e n t which m ight f a l l w ith in
t h i s e f f e c tiv e bandw idth.
The e f f e c t i v e bandwidth ta k e s i n t o
c o n s id e ra tio n o p tic a l a b e rra tio n s and i s given by
Be = X(S + .0 4 )
where
and
B
e
X
(II)
i s th e e f f e c tiv e bandw idth a t s l i t w idth S9
y
i s th e bandwidth a t I mm s l i t w idth, which i s
e m p iric a lly d eterm ined, and was obtained
g ra p h ic a lly (1 5 ).
Seme au th o rs have suggested th a t. the. d is s o c ia tio n e n erg ies
of th e la n th a n id e monoxides s te a d ily d e crea se as th e atom ic
number of th e r a r e e a r th elem ent in c re a s e s ( 9 , 2 3 ) , and o th e rs have
im p lied t h a t europium, thulium and y tte rb iu m do n o t form s ta b le
monoxides ( 5 ?19) 0 I f one assumes e q u a tio n I to be th e r e a c tio n
The ch o ice of a s s o c ia te d elem ents was made, w ith th e help of
!Ryabchikov ( l ? ) and Dana. (4) and based on th e prem ise t h a t m ineral
sam ples would be d ig e s te d i n p e rc h lo r ic acid as su g g ested by Vickery
( 20) ,
governing th e c o n c e n tra tio n o f ab so rb in g sp e c ie s i n th e f Iame5,
one would expect th e e q u ilib riu m c o n sta n t of e q u atio n IV t o be
g r e a te r th a n th e e q u ilib riu m c o n sta n t of eq u atio n I I I 9 i f th e
d is s o c ia tio n energy of REgG i s g r e a te r th a n th e d is s o c ia tio n
energy o f RKO0
REd O 4= G s= RBd + CO
(III)
REi O + Cs= RE?
( iv )
CO
where
RE^ " re p re s e n ts th e r a r e e a r th element t o be de­
term ined
and
RK
re p r e s e n ts th e r a r e e a r th In te rfe re n tV
The o v e ra ll e f f e c t would be l i t t l e change i n th e RE°
concen­
t r a t i o n i f th e c o n c e n tra tio n o f carbon i s la r g e ( l 6) compared
t o la n th a n id e monoxide,.
I t i s proposed9 however, t h a t an a d d itio n a l r e a c tio n
occurs i n th e flam e which in c re a s e s th e RE? c o n c e n tra tio n ,
r e s u l t i n g i n in c re a s e d absorption^ T h is r e a c tio n i s
RE? + REdO = REi O * RE®
(V)
and th e e x te n t t o which i t goes to th e r i g h t w ill be governed
by th e r e l a t i v e re d u c in g a b i l i t y of REi 9 which i n tu r n w ill
be governed by i t s e le c tr o n ic C a n fig u ra tio n 0
EXPERIMENTAL
A bsorption A pparatus
L lg b t Sources*
The fo llo w in g W estingbouse hollow cathode lamps
were used as l i g h t sourcesg
and erbium (WX5486) 0
dysprosium (WX5465) s holmium (WX5487)
The lamp power o u tp u t was re g u la te d by a
c o n s ta n t- c u rre n t power supply (Lambda E le c tro n ic s G o rporation9
model 71—B)o
Burner*
S ince a f u e l - r i c h oxygen /acety len e flam e was d e s ir a b le
i n t h i s in v e s tig a tio n s, a Beckman oxygen/hydrogen b u rn er was used
(#4020)o
I t was thought t h a t t h i s b u rn e r would supply a flam e
of sm a lle r t o t a l volume, and more fa v o ra b le geometry^ th e r e f o re
c o n c e n tra tin g th e atom's a v a ila b le f o r a b so rp tio n i n th e l i g h t
p a th (6)0
In additions, a sa v in g i n f u e l c o st was p re d ic te d as
th e 4020 b u rn e r d id n o t a llo w as high., a consumption as th e
sta n d a rd 4030 (o x y g en /acety len e) burner*
I t was hoped t h a t the.
attendant., d e c re a se i n s o lu tio n consum ption r a t e would be o f f s e t
by th e aforem entioned advantages, y ie ld in g n e arly , th e same
a b so rp tio n c a l ib r a t io n curves re p o rte d by Skogerboe (l9 )«
Monochromator*, A Beckman model BU q u a rtz spectrophotom eter was
used as a monochromator *
P h o to d e te c tor and Power Supply*
An. RCA IP28 p h o to m u ltip lie r
tu b e was u se d , coupled w ith a power supply d e scrib e d by Box and
Walsh (2 ) and m odified by r e p la c in g B r i t i s h tu b es w ith American
e q u iv a le n ts o
A n p lif ie r 0. i n AG tuned a m p lifie r was used t o am plify th e s ig n a l
from th e phototube*
T his a m p lifie r was o r ig in a lly d e sc rib e d by
Kalmus and Sanders (1 2 )? m od ified as re p o rte d by Skogerboe (19)
and th e t h i r d sta g e rem o d ified as shown i n F ig u re I d E s s e n tia lly ,
th e a m p lifie r i s tuned to re c e iv e a 39 cy cle s ig n a l, r e j e c t i n g
b o th 120 c y cle s ig n a l from a r t i f i c i a l lig h t/p o w e r su p p ly , and
s tr a y s ig n a ls o r ig in a tin g i n th e flame* The a m p lifie r has a
DC o u tput f o r a recorder*
R ecorder*. A B r is to l r e c o rd e r , model IRHS60, w ith a 0-10 m i l l i ­
v o lt span f u l l - s c a l e was used f o r a l l measurements *
In stru m e n ta l C onditions
S ince a d i f f e r e n t b u rn e r th a n re p o rte d by Skogerboe (19)
was u se d , b u rn e r p aram eters had t o be redeterm ined*
Reported
v a lu e s f o r hollow cathode c u rre n t and phototube v o lta g e s were
u t i l i z e d f th e maximum oxygen flow r a t e , commensurate w ith
dependable b u rn e r o p e ra tio n , s e t ; th e f u e l flow r a t e and. D
(h e ig h t above b u rn er t i p ) v a rie d t o a t t a i n th e a b so rp tio n
maxima*
The. c o n d itio n s chosen, summarized, i n Table I , r e f l e c t
e s s e n t i a l l y the'Sam e c a lib r a tio n curves re p o rte d by Skogerboe,
even though th e t o t a l flo w r a t e i s lower*
T his i s brought about
by th e b e t t e r flam e geometry produced by th e p a r t i c u l a r burner
used*
P+350v
Figure I. Last slage Iunedam plifier
T able I 6
Element
By
Ho
Er
Optimum In stru m e n ta l C onditions
Oxygen/Fuel
Eep*d , Pound
,8 0
*75
",80
,90
,90
»90
G + F(m l/m in)
Beptde Pound
7500
7500
7500
6000
6000
6000
D (mm)
E eptde Pound
30
30
30
. 24
25.
26
Lamp
m
S lit
C urrent V olts mm
(ma)
18
20
15
900
900
900
»01
»01
,01
A bsorption P rocedures
A bsorption measurements, were made by s e t t i n g .t h e mono­
chrom ator s l i t t o i t s minimum, w idth ( o0 l ) 9 fo c u s sin g on th e
a b so rp tio n l i n e and, by a d ju s tin g th e a m p lifie r g a in , s e t t i n g th e
re c o rd e r t o re a d I^, w ith a blan k i n th e flam e.
The a b so rp tio n
i n t e n s i t y , I , was th e n re a d w ith a sample s o lu tio n a s p ir a te d i n t o
th e flam e.
I n g e n e ra l, each d e te rm in a tio n was made i n t r i p l i c a t e .
S tandard S o lu tio n s
A ll c a tio n s in v e s tig a te d were p rep ared as th e p e rc h lo ra te s
p
and d isso lv e d i n a b so lu te e th a n o l. Stock s o lu tio n s
^The vanadium and aluminum s o lu tio n s were p rep a red from
th e c h lo rid e s a l t s of th e s e m e ta ls. C o rrec tio n s were made f o r
th e e ff e c t, of c h lo rid e when n e c e ssa ry .
c o n ta in in g IOs000 micrograms p e r m i l l i l i t e r ^ o f a l l m e ta ls were
prepared.=
These s o lu tio n s were d ilu te d as re q u ire d i n a b so lu te
ethanol=
3
A common e r r o r appears to occur i n tr a n s f e r r in g concen= '
t r a i l o n c a lc u la tio n s from aqueous s o lu tio n s to a lc o h o l so lu tio n s=
I n aqueous m edias ppm i s approxim ately equal to m icrogram s/m l;
b u t i n a lc o h o l s o lu tio n s an e rr o r of approxim ately 21$ i s i n t r o ­
duced by .making th e assum ption I gm EtOH - I ml a t room tem perature.o I t i s su sp ected t h a t much of th e c o n c e n tra tio n i n f o r ­
m ation i n th e l i t e r a t u r e i s i n error=
RESULTS
S p e c tra l !in te rfe re n c e s
Although c o n ce n tra te d s o lu tio n s of th e r a r e e a r th s 9
and m etals a s s o c ia te d w ith ra re , e a r th elem ents, g e n e ra lly y ie ld
no a b so rp tio n a t .th e t h r e e .a n a ly tic a l w avelengths in v e s tig a te d ,
v a ry in g amounts of em ission were passed through th e monochromator
and some of t h i s em ission s ig n a l was n o t r e je c te d by th e tuned .
a m p lifie r; th u s , an e f f e c t i v e s p e c tr a l in te rfe re n c e , was observed*
I t w ill be seen i n T able I I t h a t 9 i n g e n e ra l9 s p e c tr a l i n t e r ­
fe re n c e d ecreased as e f f e c tiv e monochromator bandw idth.decreased©
.
The e x cep tio n s to t h i s r u l e occur whenever em ission l i n e s l i e
c lo s e t o th e a n a ly tic a l wavelengths©
'I n T able I I s p e c tr a l i n te r f e r e n c e v alu e s a re l i s t e d ,
rounded to th e n e a re s t o n e -h a lf s c a le division© One. scale,
d iv is io n i s e q u iv a le n t t o one p e rc e n t transm ittance© P o s itiv e
v a lu e s in d ic a te em ission, n e g a tiv e v a lu e s in d ic a te absorption©
—>10*"
T able I I 0 S p e c tra l I n te r f e r e n c e s on Hysprosiuni9 Eolmiita and
Bcbimn i n U n its of P e rc e n t T ransm ittance
ie rfe re n t
10000
ugm/ml
La
Ce
Br
m
Sm
Ba
Gd
Tb
Dy
Ho
Er
Tm
Tb,
Lu
T
Be
Ba
Ca
Fe
Al
In
V
Th
W
Sr
4211 A
Be=6»25 A
Element Sought
Ho
4103 A
Be=5.65 A
0
0
+0.5
+1.5
+1,5
+1.0
+lo~0
+0.5
+2*0
'T '
+ 1.0
+2.0
+1.5.
+0.5
+1.5
+2.5
+3.0
0
+ 3.0
+ 2.0
+1.5
+0:5.
+2.5
+0.5
0
+0.5
+ 1.0
+ 1.0
Er
4008 A
Bq=5.25 A
0,
+1.0
0
0
+ 1 .0
0
+ 1 .0
O
0
+ 1.0
+ 2 .0
*»,
O
0
0
0
0
+0.5
0
0
+ 1 .0 ,
0
+1.5
+ 2.0
0
+ 1.5
+1.5
+ 1.0
+ 4 .0 .
+4.5
+0.5
+0.5
” 0.5
0
0
0
0
0
0
©
0
0
0
"IX"
Chemical I n te r f e r e n c e s
;
S ince i t was hoped t h a t in fo rm a tio n on th e b eh av io r of the
r a r e e a rth s i n th e flam e could he o b ta in e d , th e chem ical in te r f e r e n c e
d a ta a re p re se n te d i n two p a r t s .
The f i r s t p a r t w ill be a p u rely
ta b u la r co m p ilatio n of non r a r e e a r th i n t e r f e r e n t d a ta (T able I I I )
w h ile th e second p a r t , d e a lin g w ith r a r e e a rth elem ent i n t e r f e r ­
ence, w ill be p re se n te d b o th ta b u la r ly (T able IV) and g ra p h ic a lly
(Figure 2 ) .
I n su p p o rt of . th e h y p o th esis t h a t equation... V governs th e
enhancem ent.evidenced i n T able IV and F ig u re 2, th e fo llo w in g
i s g iv en .
The e stim a te d -o x id a tio n p o t e n t i a l s of th e r a r e e a r th
elem ents i n aqueous m edia (14) r e f l e c t a d ecrease i n re d u c in g
a b i l i t y ^ w ith in c r e a s in g atom ic number.
I t appears t o be reason­
a b le t o expect t h i s .t r e n d t o be c a r r ie d through t o , t h e c o n d itio n s
of th e flam e s in c e , from F ig u re 2, th e r e i s a g en eral d ecrease
i n enhancement ( a d e c re a se i n th e e q u ilib riu m c o n sta n t of
e q u atio n V ) as atom ic number in c r e a s e s .
The f a i l u r e o f europium
and y tte rb iu m , and t o a l e s s e r e x te n t samarium and th u liu m , to
fo llo w th e g e n eral tre n d can be ex p la in e d i f e le c tr o n ic c o n fig -
^The p o t e n t i a l s given were f o r th e r e a c tio n EB° = EE^+ + Be™«
•o ratio n s a re ta k e n i n t o account®
T able I I I 0
Chemical I n te r f e r e n c e of Eon Hare E arth M etals on
Dysprosiumj, Holmium and Erbium
In te rfe re n t
IOOG
ugn/rnl
'
Element Sought _
a l l v a lu e s given i n u n i ts of a jr
Dy
Ho
Er
250ugm/ml
150u@m/ml
200ugm/ml
T
Be
-5-0039
—
!*063
+ ®Q02
+.030
=„041
0©
S
Ea
Ca
Fe
Al
Th
U
"0I48
-o 042
-®028
-o077
=„030
=®014
=„182
=„209
=„080
+„020
=„019
■l-o054
=O009
“ ®06j2
=®026
-.2 4 2
+„067
=„034
^ AA r e p re s e n ts th e d iffe re n c e i n absorbance v a lu e
between th e sta n d a rd r a r e e a rth s o lu tio n alone and th e i n t e r f e r e
e n t s o lu tio n , c o n ta in in g a c o n c e n tra tio n of elem ent t o be
determ ined e q u iv a le n t to t h a t of th e sta n d a rd r a r e e a r th
solution®
—1 3 ”
T able IV»
CheMc a l I n te r f e r e n c e of Rare B arth Elements on
Dysprosiums HolMum and Erbium
In te rfe re n t
1000
ugm/ml
/
Element Sought
a l l v a lu e s given i n u n i t s of
Dy
Ho ■
250ugm/ml
300ugm/ml .
La'
Ce .
Ec
Hd
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Tb
Lu
'
A
• • Er
200ugm/ml
Ve 0.70
+.030
+.080
+«069
+o 051
+.031
+.022
+.071
+.049
+.024
+ .021
” «,007
+.013
-.023
+.059
+.034
+.036
+.015
+ e 010
+.055
+c 053
+.051
+ O046
+ 6033
+.043
+.059
+.003
+.041
+.015
+.054
+.049
+.053
+.013
+.002
+ 6006
+.040
+.010
.
+.033
+.045
I t i s known th a t p a r t i c u l a r l y s t a b le e le c tro n c o n fig u ra ­
tio n s a re reached when e le c tro n " s h e l l s ” a re e ith e r f i l l e d or
h a l f - f i l l e d (e g IO91 4 )e
T his i s t r u e of th e Ia n th a n id e s 9 where9
s in c e th e w ell sh ie ld e d 4 f energy l e v e l s a re b ein g f i l l e d , ' th e re
i s l i t t l e d iff e r e n c e i n ch eM cal p r o p e r tie s except when th e s e
s t a b le c o n fig u ra tio n s a re reached (1 4 921926)0
S ta b le h a l f
-1 4 -
+.080
+ .0 6 0
AA
+ .0 4 0
+.020
0
La Ce P r Ud Sm Eu
Gkl Tb Dy Ho Tm Tb Lu
Rare E arth I n t e r f e r e n t (1000 ugm/ml)
F ig u re 2.
E ffe c t of Rare E arth I n t e r f e r e n t s on th e
Absorbance of 200 ugm/ml Erbium
-1 5 -
f i l l ed o r f i l l e d 4£ energy l e v e ls would e x is t only f o r Sm (I)9
E u ( I l ) 9 G d (III) 4 f 7 c o n fig u ra tio n ; T m (I)9 Y b (Il)9 L u ( I I l) 4 f14
C o n fig u ra tio n 0
The co rresp o n d in g monoxide sp e c ie s would th en
be SmO. 9 EuO9 GdO+9 TmO 9 YbO9 LuO+0
In a re d u c in g flam e9 such
as th e one u se d . I t i s expected t h a t th e e le c tro n c o n c e n tra tio n
would be such as t o a llo w very few p o s itiv e io n s to e x i s t 9 th u s
re d u c in g th e lik lih o o d of GdO+ and LuO+ as s i g n i f i c a n t .c o n s titu ­
e n ts i n th e f u e l - r i c h o x y g en /acety len e flam e0 The c o n fig u ra tio n s
of th e n e u tr a l atoms Eti(O) 4 f^ 6 s2 and Yb(O) 4 f146 s2 a re a ls o
expected t o have in c re a s e d s t a b il i ty *
The consequences of th e p o s tu la te d e x is te n c e of th e s e
sp e c ie s a re as follows®
(1 )
The s t a b le oxide s p e c ie s of samarium, europium, thulium and
y tte rb iu m would i n h i b i t e q u atio n TV from going to com pletion,
th u s b rin g in g about a low er c o n c e n tra tio n of EE? a v a ila b le f o r
e q u a tio n V and hence few er RE® f o r excitatio n ®
T his e f f e c t would
be evidenced i n a lo w erin g of enhancement (F ig u re 2 ) e
(2 )
The e x is te n c e of s t a b le n e u tr a l atoms of europium and
y tte rb iu m would f u r t h e r i n h i b i t e q u a tio n V and cause an in c re a se d
lo w erin g of BE^ as compared t o th e e f f e c t evidenced, by o th er,, le s s
s t a b l e , s p e c ie s e
The enhancements measured show t h a t a change i n EE^ con­
c e n tr a tio n of, as much as tw enty p e rc e n t is . ta k in g place*
T his i s
*“16*=»
n o t u n reaso n ab le i n th e l i g h t of th e proposed r e a c tio n mechanism i f , as i s e stim a te d , IO^ c o ll i s i o n s p e r second occur
between RE? and RE^O^ (8)»
' A n a ly tic a l P o te n tia l
I t would seem t h a t w ith th e s e rio u s chem ical i n t e r f e r e
ences evidenced an a c tu a l a n a ly s is of contam inated r a r e .e a r t h
elem ent would be d i f f i c u l t y
In o rd e r t o a s c e r ta in i f a tech n iq u e
s im ila r t o th e r a d ia tio n b u f f e r tec h n iq u e 7 , which i s commonly
employed t o su p p ress io n iz a tio n i n sam ples w ith low io n iz a tio n
p o te n tia ls (5)$ could be u se d , fix e d c o n c e n tra tio n s of RE^
c o n ta in in g v a ry in g c o n c e n tra tio n s of i n t e r f e r e n t were run*
o f th e r e s u l t s a re p re se n te d i n F ig u re s 3™5o
Some
The le v e lin g out
of th e in te r f e r e n c e i s e v id e n t; th e s l i g h t d e crea se i n enhance=ment o c c u rrin g a t high c o n c e n tra tio n s of i n t e r f e r e n t may be due
t o a d e c re a se i n a s p ir a tio n r a t e (caused by an in c re a s e i n th e
v is c o s ity o f .t h e s o lu tio n ) w ith a consequent low ering, o f th e
r
'I n t h i s c a lc u la tio n i t was assumed t h a t a l l RE, was p re s e n t
as RB, O9 th e t r a n s i t tim e of an atom through th e flam e i s about
10 m illis e c o n d s and th e volume o f th e flam e i s
cc*
7 coo a d d itio n of an e a s ily io n iz a b le element t o an element
which s u f f e r s from a c e r t a i n degree of io n iz a tio n i t s e l f , thus
m inim izing th e e f f e c t o f sm all amounts of e a s i l y io n iz a b le e le ­
ment which might have been p re s e n t i n th e sample.
“17°
EE® c o n c e n tra tio n i n th e flame®„
I t appears as i f th e a d d itio n
o f i n t e r f e r e n t $ i f th e approxim ate c o n c e n tra tio n of i n t e r f e r e n t
i s known9 would perm it d i r e c t d e te rm in a tio n of r a r e e a rth
elem ent so u g h t.
The e f f e c t of a c o n sta n t c o n c e n tra tio n of i n t e r f e re n t.o n
v a ry in g c o n c e n tra tio n s of elem ent sought was a ls o in v e s tig a te d .
The r e s u l t s a re p re se n te d i n F ig u re s 6-8«
Once again th e c r i t ­
i c a l c o n c e n tra tio n ran g e ( s te e p e s t a sc e n t of curve) i s e v id e n t.
I t would appear t h a t s a tu r a tio n of th e flam e w ith EE® occurs
r a t h e r q u ic k ly ,. V isc o sity e f f e c ts a re n o t evidenced, s in c e a l l
s o lu tio n s a re r e l a t i v e l y d i l u t e .
D ata
The d e v ia tio n a t a n in e ty - f iv e p e rc e n t confidence le v e l
( l l ) for. at. l e a s t f o r t y d e te rm in a tio n s o f th e sta n d a rd s o lu tio n
of each elem ent in v e s tig a te d (Dy9 Ho5, E r) i s p re se n te d "below,
25Ougm/ml Dy s 3 ,4 #
3G0ugna/ml Ho s 2 ,3 #
2O0ugm/ml Er s I ,
O i ' • ;- • ■
Dysprosium does n o t behave i n . t h i s manner9 presum ably
because enhancement in c re a s e s s te a d ily a t h ig h e r i n t e r f e r e n t
c o n c e n tra tio n s , overshad owing th e sm all, v is c o s ity e f f e c t . In
th e o th e r elem ents in v e s tig a te d i t appears t h a t enhancement
re a c h e s a maximum and th e v is c o s ity e f f e c t ta k e s over a t high
i n t e r f e r e n t l e v e ls .
-
••18—
+ .0 8 0
250 Dy + La
+.060
+.040
q 250
Dy + Ho
°250 Dy + Br
+ .020
1000
3000
5000
I n t e r f e r e n t C o n cen tratio n (ugm/ml)
F ig u re 3.
E ffe c t of V arying Amounts of I n t e r f e r e n t on
250 ugn/ml Dysprosium
Q 300 Ho + Dy
+ .0 4 0
+ .0 3 0
+ .020
& 300 Ho + La
+ .010
300 Ho + Er
0
F ig u re 4.
1000
I n t e r f e r e n t C o n cen tratio n (ugm/ml)
E ffe c t of V arying Amounts of I n t e r f e r e n t on 300 ugn/ml
Holmium
-1 9 -
+ .0 8 0
200 Er + Dy
+ .0 6 0
'4 200 Br + La
+ .0 2 0
200 Er + Ho
0
F ig u re 5»
1000
5000
I n t e r f e r e n t C o n cen tratio n (ugm/ml)
E ffe c t of V arying Amounts o f I n t e r f e r e n t on
200 ugm/ml Erbium
—20—
+.080
-
+.060
'
+.020
*
Dy + 1000 La
Dy + 1000 Er
O Dy + 1000 Ho
Dysprosium C o n cen tratio n (ugm/ml)
F ig u re 6.
E ffe c t of 1000 ugm/ml I n t e r f e r e n t on Varying
C on cen tratio n s of Dysprosium
+ . 0 4 0
«
+ .0 3 0
-
Ho + 1000
Ho + 1000
+.010
100
200
300
Holmium C o ncentration (ugm/ml)
F ig u re 7»
E ffe c t of 1000 ugm/ml I n t e r f e r e n t on V arying
C o n cen tratio n s of Holmium
—21—
+.080
Br + 1000 La
+ .0 6 0
g
O
Br + 1000 Dy
Er + 1000 Ho
+ .0 2 0
ErLium C o n cen tratio n (ugjn/ml)
F ig u re 8 .
E ffe c t of 1000 ugm/ml I n t e r f e r e n t on V arying
C on cen tratio n s of Erbium
SUMMABT
The f e a s i b i l i t y exf th e d e te rm in a tio n of a t l e a s t some o f
th e r a r e e a r th elem ents i n p resen ce of each o th e r has been
dem onstrated,,
I t rem ains t o be shown what th e e f f e c t o f many
r a r e e a r th i n t e r f e r e n t a on m e elem ent would be^ and i f pro­
cedures could be dev ised f o r d i r e c t a n a ly s is of ores*
Elements
such as aluminum have such a s e rio u s d e p re ss iv e e f f e c t t h a t removal
would appear t o h e .th e only recourse, i f re a so n a b le d e te c tio n .
s e n s i t i v i t i e s were t o be m aintained,,.
I t i s p o s s ib le t h a t e ith e r
th e i n t e r f e r e n t ' o r th e elem ent to be determ ined could be p r e f e r ­
e n t i a l l y com pleted by th e a d d itio n of a com pleting agent such
as has been done i n th e case of th e i n h i b i t i o n of calcium
em ission by phosphorous ( 24s25)o
C o n sid eratio n of d is s o c ia tio n energy phenomena alone
appears t o be g ro s s ly in ad eq u ate t o e x p la in th e s e flam e p ro c e ss e s0
R e su lts o th e r th a n th o se expected on th e b a s is of p re v io u s ly
proposed arguments (7 919) a re o b ta in e d ,
A p la u s ib le , sim ple
redox phenomenon, has been proposed t o e x p la in th e .O bservations0 .
With th e d e te rm in a tio n of th e o s c i l l a t o r s tre n g th s of th e absorp­
t i o n l i n e s , th e u se o f a pre-m ix b u rn e r re p o rte d by K h ise ley, et.
^From th e r e s u l t s on em ission work re p o rte d by D8S ilv a (3)
e t a lo , who rep o rted , n o n in te rfe re n c e when complex' r a r e e a r th
system s were a n a ly z e d ,' i t ' i s p o s s ib le t h a t i n t e r element.' e f f e c ts
observed i n a tu rb u le n t flam e may be e lim in a te d by th e u se of
a pre-m ix b u rn e r0
"23"
alo (7 g l3) and th e use ©f. a m u ltip a ss o p tic a l system ( l ) t©
in c re a s e th e s e n s i t i v i t y , th e e q u ilib riu m c o n sta n ts f o r equations
I I I - T should be determ inable^
LITERATUHB CITED
1»
A l l a n 9 BoEe9 S p e o t r o c h im e A d ta 17« 4^7 ( l 9 6 l ) »
2»
Box9 GeP o9 .Walsh9 A09 Spectrochim® A o t a l S 9 255 (1960)»
3®
B' S ilv a 9 AoPo9 e t a l a 9 Anale Chem0 SS9 532 (1964)«
4a
Dana9 EeSo9 mA Textbook of M n e ra lo g y 9M M le y 9 Few T erk 9 .1932®
5o
Dean9 J 0A09 "Flame Photom etry9" HcGraw-Hill9. Few T ork9 19'60O
6»
E lw e ll9 WeTo9 G id ley 9 JeA0F e9 "Atomic A bsorption S p e c tro Photem etry9" M acm illan9. Few York9 1962®
Te
F a s s e l9 V0Aa9 e t a l 09. Speetrochim 0 A cta IS 9 1127 (1962)®
S0,
F r o s t 9 AiA09' P earso n 9 B0G09 " K in e tic s and Meohanism9" W iley9
Few T ork9 1953®
9»
H erzherg9 G09 ltM oleoular S p e c tra and M olecular-S tru o tu re o /10
S p e c tra of D iatom ic M olecules9" D0Van F o stra n d 9 P rin o e to n 9
Few J e r s e y 9 195©e ■
10®
H eslop9 B0B09 Bdbinson9 P0L09 "In o rg an ic C hem istry9u
E ls e v ie r 9 Few York9 1953®
11®
H oel9 P 0G09 "Elem entary S t a t i s t i o s 9" W iley9 Few York9 19SG0
12®
Kalmus9 H0P 09 S an d ers9 M09 E le c tro n ic s 23s2® 84 ( J u ly 9 1950)»
13»
K n ise le y 9 B0F 09 e t al®9 Anal0 Chem0 3^,9 91® (1963)»
14«
M o e lle r9 -T®,—"The Chemistry of th e L a n th a n id e s," B einhdld9
Few York9 1963o
15a
F a tio n a l T echnioal L abs9 Bull® 911=-F9 So0 Pasadena9 G a lif09
1949»
IS®
F o r r is h 9 E0G0W09 American S c i e n t i s t ^O9 131 (1962)®
17®
ByabcMkov9 DoI 0;, "Bare E arth M e ta ls9" Academy of S cien ces,
Moscow, USSB9 .1959»
IS®
Schuhknecht9 W09 S c h in k el9 H09 Z0 Anal® Chem® 162® 266 (1958)*
19»
Skogerboe9 BoK09 Ph0De ;T h e s is 9 Montana S ta te C ollege,
Bozeman9 Montana9 1963»
—25“
20 ».
V ickeryj E0C0 g' “A n a ly tic a l Chem istry of th e Bare E a rth s 911
Pergamon P r e s s 9 -IJew Tork9 1961«,
21 o
V ickery9"E0C i9 "Chem istry of th e L anthanons9" B u tte rw o rth s9
London9 1953»
22 »
Walsh9 Ao9 Spectrbchim e Aota J iS 108 (1955)»
23?
Walsh9 Ao9 e t al©9 Jo .-Am* Ceram© Soc0 ^B9 2 2 9 . ( i 960)©
24©
W irts o h a fte r9 J 0Be9 S cience 125» 603 (1957)»
25»
Yofe9 J o
26©
T o s t9 .B0Mo9 E u sse l9 E o G am er9 Ce S o "The Eare E arth
Elements and T h eir Compounds,." W iley9 Uew T ork9 1947»
9
F i n k e ls te in 9 Eo
. 9
9
Anal0 Claim© A cta 1£9 166 (1958)®.
9
MOMTAIua
—
...
3 1762 10013336 0