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Determination of terbium and dysprosium by atomic absorption spectrometry
Analytica Chimica Acta, 66 (1973) 343-349 t~) Elsevier Scientific P u b l i s h i n g C o m p a n y , A m s t e r d a m - P r i n t e d in The N e t h e r l a n d s
343
D E T E R M I N A T I O N O F T E R B I U M A N D D Y S P R O S I U M BY A T O M I C ABSORPTION SPECTROMETRY TOSHIO ISHIZUKA and HIROSHI SUNAHARA Government Industrial Research Institute, 1-1 Hirate-machi, Kita-ku, Nagoya (Japan.) (Received 17th J a n u a r y 1973)
With increasing d e m a n d for rare-earth elements for industrial purposes, rapid a nd accurate analytical m e t h o d s for individual rare-earth elements in the presence of o t h e r rare-earth elements are of growing importance. T e r b i u m an d dysprosium have been determined by spectrophotometry, emission spectrography, flame emission spectrometry, a t o m i c absorption spectrometry, X-ray fluorescence spectrometry, X-ray or electron excited luminescence spectrometry, n e u t r o n activation, mass spectrometry, etc. A m o n g these analytical methods, atomic absorption spectrometry has several advantages, such as easy pretreatment of a sample, easy operation of the instrument, and freedom from spectral interferences. Several investigators 1-s have studied the atomic absorption behavior of terbium, dysprosium and other rare-earth elements. A few studies of matrix effects on such d e t e i m i n a t i o n s a n d of practical determinations of individual rareearth elements in rare-earth mixtures by atomic absorption spectrometry have been reported6"7, but no details have been published for terbium and dysprosium. In this w o r k , the effects of several inorganic acids, c o m m o n metal ions, rare-earth elements a nd organic solvents on the atomic absorption of t e r b i u m a n d dysprosium were studied, a n d terbium an d d y s p r o s i u m were dete~r~fined in synthetic and practical samples. EXPERIMENTAL
Apparatus A N i p p o n Jarrell-Ash m o d e l AA-1E a t o m i c absorption-flame emission spectrometer with a nitrous oxide-acetylene flame slit burner was used. VarianT e c h t r o n hollow-cathode lamps for terbium and dysprosium were used as radiation sources. A J o h n F l uke 415B high-voltage power supply was used to power a H T V R-106 photomultiplier. A preamplifier, based on Philbriek-Nexas operational amplifiers and a Y o k o g a w a - H e w l e t t P a c k a r d 4403 t u n e d null detector, was used to amplify the output of photomultiplier. A National VP-654A pen recorder was also used.
Reagents Stock 'solutions containing 20 mg m1-1 of terbium or dysprosium were p r e p a r e d by dissolving these oxides (Shin-Etsu Chemical Co., 99.99~/o purity) in 0.5 M hydrochloric acid. Other rare-earth stock solutions were p r e p a r e d by
344
T. I S H I Z U K A , H. S U N A H A R A
dissolving the rare-earth oxides (Shin-Etsu C h e m i c a l Co., 99.9 or 99.99~/o purity) in hydrochloric acid. All other chemicals were prepared from analytical-grade reagents ( W a k o P u r e Chemicals).
Procedure T h e optimal experimental conditions were established by atomizing solutions containing 300 p.p.m, terbium and 100 p.p.m, dysprosium, respectively (Table I). TABLE I EXPERIMENTAL CONDITIONS
Terbium W a v e l e n g t h (nm) 432.6 Slitwidth (/am) 100 Spectral b a n d w i d t h ( n m ) 0.16 C o m b u s t i o n gas flow r a t e (1 m i n - i) NzO 6.7 C2Hz 4.6 HolFow-eathode l a m p c u r r e n t (mA) 16 O b s e r v a t i o n height a b o v e 7 the b u r n e r head ( r a m )
Dysprosium 404.6 100 0.16 6.7 4.6 16 7
RESULTS AND DISCUSSION
Effects o f inorganic acids I n the determination of terbium a n d dysprosium in various samples, the samples must be dissolved in inorganic acids, the kind and concentration of which m u s t therefore be considered. The effects o f several inorganic acids in concentrations of 10-3-3 M on the absorption of terbium (300 p.p.m.) and dysprosium (100 p.p.m.) were investigated. The acids used were hydrochloric acid, nitric acid, perchloric acid, sulforic acid and phosphoric acid. The results are shown in Figs. 1 a nd 2. H y d r o c h l o r i c acid up to 3 M and nitric acid up to 0.1 M had little effect o n the absorption of terbium. Nitric acid at 0.3-3 M increased the absorption by 15-25~/o, perchloric acid at 3 - 1 0 - 3 - 3 M by 30-45%, sulfuric acid at 10-3-0.3 M by 20--35%, a n d phosphoric acid at 10- 3--0.3 M by 15-25~o. Sulfuric acid at 3 M decreased the absorption by 35%, and phosphoric acid at 3 M by 45%. Nitric acid up to 3 M did not allect the absorption of dysprosium. Hydrochloric acid at 0.1-1 M increased th e a b s o r p t i o n by 10-20~o, sulfuric acid at 10-3-0.1 M by 10-20y/o, and phosphoric acid at 10-3-0.3 M by 20--30%. The absorption decreased gradually with increasing concentrations of perchloric acid, a 35~/o decrease being observed at 3 M perchloric acid. Sulfuric acid at 3 M decreased the absorption by 40%, an d p h o s p h o r i c acid at 3 M by 50~o. It can b e seen that hydrochloric, nitric a n d perchloric acids each had different effects on the absorption of t erb iu m a n d dysprosium.
T E R B I U M A N D D Y S P R O S I U M BY A.A.S.
345 &--..--A
/,---~--t-..~: - - - ~ ' "
0.15
u e
g
O.lO
0.10
~0O5
•:
"~,~.o_
< 0.05 0
1 -3
10-2
10-1
Added acid concn.. M
1
C
t ~, a
0
a
i
10 .-3 10 -.2 10 "1 Added acid concn..M
i
1
Fig. 1. Effects of inorganic acids on the a b s o r p t i o n o r terbium. Tb cohen. 300 p.p.rn. ( O ) HCi, ( A ) H N O 3 , (['-1) HCIO4, ( O ) H 2 S O , , ( A ) H 3 P O 4 . Fig. 2. Effects o f i n o r g a n i c acids on t h e ' a b s o r p t i o n o f dysprosium. Dy concn. HCI, ( A ) H N O 3 , ([-I) H C I O , . ( 0 ) H 2 S 0 4 , ( A ) H s P O 4 .
100 p.p.m. ( O )
Effects of metal ions S o m e c o m m o n metals, as well as o t h e r r a r e - e a r t h metals, w e r e selected to s t u d y i n t e r f e r i n g effects o n t h e a b s o r p t i o n o f t e r b i u m a n d d y s p r o s i u m ; t h e c o n c e n t r a t i o n s s t u d i e d r a n g e d f r o m 10 to 10000 p.p.m, with 300 p.p.m, t e r b i u m o r 100 p . p . m , d y s p r o s i u m . T h e c o m m o n m e t a l i o n s used were Li, N a , K, M g , Ca, Sr, Ba, Cr, M n , Fe, Ni, Cu, Z n , P b a n d AI. T h e results are s h o w n in Figs. 3 a n d 4. T h e a b s o r p t i o n o f t e r b i u m d e c r e a s e d in t h e p r e s e n c e o f 3 0 - 3 0 0 p.p.m, o f t h e f o l l o w i n g m e t a l ions, b u t i n c r e a s e d by 2 5 - 9 0 % in the presence o f 3 0 0 0 - 1 0 0 0 0 p . p . m . : Li, N a , K, M g , Ca, Cr, M n , Fe, N i a n d Pb. Z i n c ( 3 0 - 3 0 0 0 p.p.m.) d e c r e a s e d t h e a b s o r p t i o n . T h e a b s o r p t i o n a l m o s t d o u b l e d in the p r e s e n c e o f 10(~)10000 p.p.m, s t r o n t i u m . T h e a b s o r p t i o n increased with i n c r e a s i n g c o n c e n t r a t i o n s o f b a r i u m ; 10000 p . p . m , i n c r e a s e d t h e a b s o r p t i o n by 90%. C o p p e r u p to 300 p.p.m, h a d little effect b u t 1 0 0 0 - 1 0 0 0 0 p.p.m, i n c r e a s e d the a b s o r b a n c e by 4 0 - 5 0 % . A n a b s o r p t i o n increase o f 35% w a s c a u s e d by 300 p.p.m, a l u m i n u m b u t a d e c r e a s e o f 70% was c a u s e d by 10000 p.p.m. T h e a b s o r p t i o n o f d y s p r o s i u m d e c r e a s e d by 2 5 - 7 5 % in t h e p r e s e n c e o f 1000-10000 p.p.m, o f Li, N a , K, M g , Ca, Sr, Ba a n d Cr. T h e p r e s e n c e o f 3 0 0 0 - 1 0 0 0 0 p.p.m, m a n g a n e s e or lead i n c r e a s e d the a b s o r p t i o n by 20--40%. I r o n , nickel, c o p p e r a n d zinc u p to 10000 p.p.m, h a d little effect. T h e a b s o r p t i o n inc r e a s e d by 2 5 - 4 0 % in t h e p r e s e n c e o f 100-300 p.p.m, of a l u m i n u m , b u t d e c r e a s e d by 65~,~ in t h e p r e s e n c e o f 10000 p . p . m . The absorption of terbium and dysprosium increased with increasing conc e n t r a t i o n s o f o t h e r r a r e - e a r t h e l e m e n t s . T h e p r e s e n c e o f 3000 p.p.m, o f t h e s e i n c r e a s e d t h e a b s o r p t i o n o f t e r b i u m by 7 0 - 1 0 0 % a n d t h a t o f d y s p r o s i u m by 50-80%. As s h o w n in Fig. 4, t h e effects o f t h e o t h e r rare e a r t h s o n t h e a b s o r p t i o n o f t e r b i u m a n d d y s p r o s i u m were m a i n l y classified w i t h i n t h r e e g r o u p s .
Effects of organic solvents T h e effects o f a l c o h o l s o n t h e a b s o r p t i o n o f t e r b i u m (300 p.p.m.) a n d
346
T. ISHIZUKA, H. S U N A H A R A (b)
0.20
0.20
0.15
o~
0.15
g
o
z~
..=..a
0.10
0.10
T° JO
<~ 0.05
0.05
~ "
1
b
i
Added
O20
1000
metal
I
100(0)
0
ion c o n c n . , p . p . m .
I
!
i
qcx)
1000
10000
(d).
0.20
Dy
0.10
I
10
"Added metal concn.,p.pm.
(c)
0.15
g
I
100
~
g
0.15
Dy
~
g
:
0.05
.a: 0.05
~-% ~ 1
0
Added
, 100
, 1000
, 10000
m e t a l cohen., p.p.m.
0
m %
0
i
i
10
100
i
1000
I
10000
Added metal concn.,p.p.m.
Fig. 3. Effects of common metal ions on the absorption of terbium and dysprosium. Tb conch. 300 p.p.m.; Dy conch. 100 p.p.m, a: (C)) Li, ( A ) Na, (I-1) K. b: ( O ) Mg, ( A ) Ca, (r-7) Sr, ( O ) Ba, c: ( O ) Fe, ( A ) Ni, (I-1) Cu, (O) Zn. d: (C)) Cr, ( A ) Mn, (r-l) Pb, (O) AI.
~ c ~
Lo,Pr, Nd, Srn0 Eu Y, E r , T m
lobo
106oo
0.20
0.15
8 t-, o <¢
0.10
JO
0.05
o
A d d e d m e t a l i o n c o n c h . , p.p.m.
Fig. 4. Effects of rare-earth elements on the absorption of terbium and dysprosium. Tb cohen. 300 p.p.m.; DY conch. 100 p.p.m.
T E R B I U M A N D D Y S P R O S I U M BY A.A.S.
347
TABLE II EFFECTS OF ALCOHOLS ON THE ABSORPTION OF TERBIUM AND DYSPROSIUM
Solvent (v/v %)
Aqueous M e t h a n o l 40 80 95 Ethanol 40 80 95 P r o p a n o l 40 80 95 •
Absorption ratio Terbium
Dysprosium
1.00 1.03 1.82 1.95 0.92 1.52 2.01 1.15 1.29 1.55
1.00 0.80 1.77 2.58 0.69 1.42 2.19 0.91 1.05 1.39
d y s p r o s i u m (100 p.p.m.) w e r e investigated. M e t h a n o l , e t h a n o l a n d p r o p a n o l were u s e d in a m o u n t s o f 40, 80 a n d 95% in v o l u m e . T a b l e II s h o w s t h a t the p r e s e n c e o f 4 0 % a l c o h o l t e n d e d to d e c r e a s e t h e a b s o r p t i o n , p a r t i c u l a r l y for d y s p r o s i u m , w h e r e a s 8 0 % - 9 5 % a l c o h o l i c s o l u t i o n s c a u s e d m a r k e d increases for b o t h metals.
Calibration curves
C a l i b r a t i o n c u r v e s for t e r b i u m in t h e r a n g e 0 - 1 0 0 0 p.p.m, a n d d y s p r o s i u m in t h e r a n g e 0 - 2 0 0 p.p.m, are s h o w n in Figs. 5 a n d 6. C u r v e s w e r e p r e p a r e d f o r t e r b i u m o r d y s p r o s i u m alone, a n d for t e r b i u m o r d y s p r o s i u m w i t h a d d i t i o n o f 1% p o t a s s i u m , 1% y t t r i u m , or 1% l a n t h a n u m . T h e c a l i b r a t i o n curve for t e r b i u m a l o n e (Fig. 5) was c o n c a v e in t h e r a n g e 0 - 4 0 0 p.p.m, a n d convex in Ob Q4 Q3
o 3 ~ }o2 8 =
Q2
~ !
0
200
400
600
I
800
T b concn., p.p,m.
0.1
!
1000
0
4b
8b Oy
1/o
1, o
concn., p.p.m.
Fig. 5. C a l i b r a t i o n curves for terbium. ( Q ) Tb alone, ( O ) Tb-t21% K , ( A ) T b + l ~ / o Y, (;-1) T b + l % La. Fig. 6. C a l i b r a t i o n curves for dysprosium. ( O ) D y alone, ( O ) D y + l % D y + 1% La.
K, ( A )
D y + l ~ / o Y, (I-1)
348
T. I S H I Z U K A .
H. S U N A H A R A
the range 8 0 0 - 1 0 0 0 p.p.m.; the sensitivity was increased by addition o f potassium, yttrium o r lanthanum, the curves b e c o m i n g linear in the range 0 - 6 0 0 p.p.m., but still b e n d i n g slightly in the range 6 0 0 - 1 0 0 0 p.p.m.. T h e cafibration curve for dysprosium alone (Fig. 6) was linear in the range 0 - 2 0 0 p.p.m.; the additives increased the sensitivity but greatly decreased the linear range.
Analysis o f synthetic samples Samples c o n t a i n i n g v a r i o u s - a m o u n t s o f terbium and d y s p r o s i u m oxides were m a d e up w i t h yttria as s h o w n in Table III. The total c o n c e n t r a t i o n o f Tb4OT, DY2Oa and Y2Oa in each sample solution w a s 1 g/100 ml. S a m p l e s o l u t i o n s c o n t a i n i n g high c o n c e n t r a t i o n s o f terbium or dysprosium were diluted to an appropriate c o n c e n t r a t i o n for the a t o m i c a b s o r p t i o n measurements, and 19/o o f p o t a s s i u m ion w a s added to this solution for b o t h terbium and dysprosium. T h e results o b t a i n e d are s h o w n in Table III. The values found for terbium in TABLE
III
RESULTS
Sample no.
FOR
TERBIUM
DYSPROSIUM
IN SYNTHETIC
T b 4 0 7 concn.
Theore-
SAMPLES"
D Y 2 0 a conch.
Found
tical
1 2 3 4 5 6
AND
(%)
(%)
30.0 10.0 3.0 1.0 0.3 0.1
29.2 10.5 3.10 0.96 0.31 --
Relative
Theore-
error
tical
(%)
(%)
+2.7 +5.0 +3.3 --4.0 -3.3 --
0.1 0.3 1.0 3.0 10.0 30.0
0.t0 0.31 0.97 2.85 10.3 30.3
(%)
Found
Relative error
(%)
0 +3.3 --3.0 +5.0 +3.0 +1.0
" S a m p l e c o m p o s i t i o n : the a m o u n t s o f T b 4 0 7
and D y 2 O a taken are given in c o l u m n s 2 a n d 5 o f the Table; in all cases, the c o m p o s i t i o n was m a d e up to 100% with Y 2 0 3.
TABLE
IV
RESULTS
S a m p l e no.
1 2 3 4 5
FOR
TERBIUM
AND
DYSPROSIUM
T b 4 0 7 conch.
IN SAMPLES
OF
RARE-EARTH
D Y 2 0 a conch.
Conch.
s,
by FE b
Collcn.
s,
by FE b
(%)
(%)
(%)
(%)
(%)
(0.4)
1.27 0.76 --0.41
6.0 6.0 --4.9
1.38 0.94 --0.33
3.98 2.36 0.71 0.04 0t.58
2.7 1.2 2.3 6.6 4.1
4.08 2.45 0.74 0.04 0.61
E a c h value is the m e a n o f 5 determinations. b Values measured by a flame e m i s s i o n m e t h o d .
OXIDES a
T E R B I U M A N D D Y S P R O S I U M BY A.A.S.
349
the r a n g e 0.3-30.09/o Tb,,O7 h a d a relative e r r o r o f + 5 . 0 to --4.09/0 c o m p a r e d to the theoretical values; 0.19/o T b , O7 c o u l d n o t be d e t e r m i n e d accurately. T h e values f o u n d for d y s p r o s i u m in the r a n g e 0.1-30.09/o D y 2 0 3 h a d a relative e r r o r of + 5.0 to --3.09/0 c o m p a r e d t o the t h e o r e t i c a l values.
Analysis o f rare-earth oxides T e r b i u m a n d d y s p r o s i u m w e r e d e t e r m i n e d in practical samples o f raree a r t h oxides (a c r u d e grade" m a t e r i a l u s e d in an ion-exchange s e p a r a t i o n process). T h e r a r e earth oxides (1 g) were dissolved in h y d r o c h l o r i c acid, a n d diluted ..... to a v o l u m e o f 100 ml. T h e results ( T a b l e IV) are c o n s i d e r e d to be satisfactory, a n d are in g o o d a g r e e m e n t with .results o b t a i n e d by a flame-emission method. SUMMARY
F o r the d e t e r m i n a t i o n o f t e r b i u m a n d d y s p r o s i u m by a t o m i c a b s o r p t i o n s p e c t r o m e t r y , the effects o f several i n o r g a n i c acids, metal ions a n d alcohols were studied. T h e two m e t a l s were d e t e r m i n e d in the presence o f yttria a n d in raree a r t h oxides with satisfactory results. RI~SUMI~
U n e 6tude est effectu6e sur la s p e c t r o m 6 t r i e par a b s o r p t i o n a t o m i q u e d u t e r b i u m et d u d y s p r o s i u m . O n e x a m i n e l'influence de divers acides inorganiques, de divers ions m~talliques et des alcools. Les dosages de ces deux m 6 t a u x o n t d o n n ~ des r6sultats satisfaisants, en pr6sence d ' o x y d e d ' y t t r i u m et d ' o x y d e s de terres rares. ZUSAM MENFASSUNG
D e r Einfluss v o n v e r s c h i e d e n e n a n o r g a n i s c h e n Siiuren, M e t a l l i o n e n u n d A l k o h o l e n auf d i e B e s t i m m u n g v o n T e r b i u m u n d D y s p r o s i u m d u r c h A t o m a b s o r p t i o n s s p e k t r o m e t r i e w u r d e u n t e r s u c h t . D i e beiden Metalle k o n n t e n in G e g e n w a r t y o n Y t t r i u m o x i d u n d in S e l t e n e r d - O x i d e n mit zufriedenstellenden Ergebnissen b e s t i m m t werden. REFERENCES 1 2 3 4 5 6 7 8
V. G. Mossotti and V. A. Fassei, Spectrochim. Acta, 20 (1964) I 117. M. D. Amos and J. B. Willis. Spectrochim. Acta, 22 (1966) 1325. D. C. Manning, At. Absorpt. Newsl., 5 (1966) 127. J. K i n n u n e n and O. Lidsjo, Chem. Anal., 56 (1967) 25. R. J. Jaworowski, R. P. Weberling a n d D. J. Bracco, Anal. Chim. Acta, 37 (1967) 284. J. C. V a n Loon, J. H. G a l b r a i t h a n d H. M. Aarden, Analyst° 96 (1971) 47. A. M. Szaplonczay, Analyst, 97 (1972) 29. Sh. (3. Melamed, A. M. Saltikova a n d L. F. Tchelidze, Zavod. Lab., 37 (1971) 166.
343
D E T E R M I N A T I O N O F T E R B I U M A N D D Y S P R O S I U M BY A T O M I C ABSORPTION SPECTROMETRY TOSHIO ISHIZUKA and HIROSHI SUNAHARA Government Industrial Research Institute, 1-1 Hirate-machi, Kita-ku, Nagoya (Japan.) (Received 17th J a n u a r y 1973)
With increasing d e m a n d for rare-earth elements for industrial purposes, rapid a nd accurate analytical m e t h o d s for individual rare-earth elements in the presence of o t h e r rare-earth elements are of growing importance. T e r b i u m an d dysprosium have been determined by spectrophotometry, emission spectrography, flame emission spectrometry, a t o m i c absorption spectrometry, X-ray fluorescence spectrometry, X-ray or electron excited luminescence spectrometry, n e u t r o n activation, mass spectrometry, etc. A m o n g these analytical methods, atomic absorption spectrometry has several advantages, such as easy pretreatment of a sample, easy operation of the instrument, and freedom from spectral interferences. Several investigators 1-s have studied the atomic absorption behavior of terbium, dysprosium and other rare-earth elements. A few studies of matrix effects on such d e t e i m i n a t i o n s a n d of practical determinations of individual rareearth elements in rare-earth mixtures by atomic absorption spectrometry have been reported6"7, but no details have been published for terbium and dysprosium. In this w o r k , the effects of several inorganic acids, c o m m o n metal ions, rare-earth elements a nd organic solvents on the atomic absorption of t e r b i u m a n d dysprosium were studied, a n d terbium an d d y s p r o s i u m were dete~r~fined in synthetic and practical samples. EXPERIMENTAL
Apparatus A N i p p o n Jarrell-Ash m o d e l AA-1E a t o m i c absorption-flame emission spectrometer with a nitrous oxide-acetylene flame slit burner was used. VarianT e c h t r o n hollow-cathode lamps for terbium and dysprosium were used as radiation sources. A J o h n F l uke 415B high-voltage power supply was used to power a H T V R-106 photomultiplier. A preamplifier, based on Philbriek-Nexas operational amplifiers and a Y o k o g a w a - H e w l e t t P a c k a r d 4403 t u n e d null detector, was used to amplify the output of photomultiplier. A National VP-654A pen recorder was also used.
Reagents Stock 'solutions containing 20 mg m1-1 of terbium or dysprosium were p r e p a r e d by dissolving these oxides (Shin-Etsu Chemical Co., 99.99~/o purity) in 0.5 M hydrochloric acid. Other rare-earth stock solutions were p r e p a r e d by
344
T. I S H I Z U K A , H. S U N A H A R A
dissolving the rare-earth oxides (Shin-Etsu C h e m i c a l Co., 99.9 or 99.99~/o purity) in hydrochloric acid. All other chemicals were prepared from analytical-grade reagents ( W a k o P u r e Chemicals).
Procedure T h e optimal experimental conditions were established by atomizing solutions containing 300 p.p.m, terbium and 100 p.p.m, dysprosium, respectively (Table I). TABLE I EXPERIMENTAL CONDITIONS
Terbium W a v e l e n g t h (nm) 432.6 Slitwidth (/am) 100 Spectral b a n d w i d t h ( n m ) 0.16 C o m b u s t i o n gas flow r a t e (1 m i n - i) NzO 6.7 C2Hz 4.6 HolFow-eathode l a m p c u r r e n t (mA) 16 O b s e r v a t i o n height a b o v e 7 the b u r n e r head ( r a m )
Dysprosium 404.6 100 0.16 6.7 4.6 16 7
RESULTS AND DISCUSSION
Effects o f inorganic acids I n the determination of terbium a n d dysprosium in various samples, the samples must be dissolved in inorganic acids, the kind and concentration of which m u s t therefore be considered. The effects o f several inorganic acids in concentrations of 10-3-3 M on the absorption of terbium (300 p.p.m.) and dysprosium (100 p.p.m.) were investigated. The acids used were hydrochloric acid, nitric acid, perchloric acid, sulforic acid and phosphoric acid. The results are shown in Figs. 1 a nd 2. H y d r o c h l o r i c acid up to 3 M and nitric acid up to 0.1 M had little effect o n the absorption of terbium. Nitric acid at 0.3-3 M increased the absorption by 15-25~/o, perchloric acid at 3 - 1 0 - 3 - 3 M by 30-45%, sulfuric acid at 10-3-0.3 M by 20--35%, a n d phosphoric acid at 10- 3--0.3 M by 15-25~o. Sulfuric acid at 3 M decreased the absorption by 35%, and phosphoric acid at 3 M by 45%. Nitric acid up to 3 M did not allect the absorption of dysprosium. Hydrochloric acid at 0.1-1 M increased th e a b s o r p t i o n by 10-20~o, sulfuric acid at 10-3-0.1 M by 10-20y/o, and phosphoric acid at 10-3-0.3 M by 20--30%. The absorption decreased gradually with increasing concentrations of perchloric acid, a 35~/o decrease being observed at 3 M perchloric acid. Sulfuric acid at 3 M decreased the absorption by 40%, an d p h o s p h o r i c acid at 3 M by 50~o. It can b e seen that hydrochloric, nitric a n d perchloric acids each had different effects on the absorption of t erb iu m a n d dysprosium.
T E R B I U M A N D D Y S P R O S I U M BY A.A.S.
345 &--..--A
/,---~--t-..~: - - - ~ ' "
0.15
u e
g
O.lO
0.10
~0O5
•:
"~,~.o_
< 0.05 0
1 -3
10-2
10-1
Added acid concn.. M
1
C
t ~, a
0
a
i
10 .-3 10 -.2 10 "1 Added acid concn..M
i
1
Fig. 1. Effects of inorganic acids on the a b s o r p t i o n o r terbium. Tb cohen. 300 p.p.rn. ( O ) HCi, ( A ) H N O 3 , (['-1) HCIO4, ( O ) H 2 S O , , ( A ) H 3 P O 4 . Fig. 2. Effects o f i n o r g a n i c acids on t h e ' a b s o r p t i o n o f dysprosium. Dy concn. HCI, ( A ) H N O 3 , ([-I) H C I O , . ( 0 ) H 2 S 0 4 , ( A ) H s P O 4 .
100 p.p.m. ( O )
Effects of metal ions S o m e c o m m o n metals, as well as o t h e r r a r e - e a r t h metals, w e r e selected to s t u d y i n t e r f e r i n g effects o n t h e a b s o r p t i o n o f t e r b i u m a n d d y s p r o s i u m ; t h e c o n c e n t r a t i o n s s t u d i e d r a n g e d f r o m 10 to 10000 p.p.m, with 300 p.p.m, t e r b i u m o r 100 p . p . m , d y s p r o s i u m . T h e c o m m o n m e t a l i o n s used were Li, N a , K, M g , Ca, Sr, Ba, Cr, M n , Fe, Ni, Cu, Z n , P b a n d AI. T h e results are s h o w n in Figs. 3 a n d 4. T h e a b s o r p t i o n o f t e r b i u m d e c r e a s e d in t h e p r e s e n c e o f 3 0 - 3 0 0 p.p.m, o f t h e f o l l o w i n g m e t a l ions, b u t i n c r e a s e d by 2 5 - 9 0 % in the presence o f 3 0 0 0 - 1 0 0 0 0 p . p . m . : Li, N a , K, M g , Ca, Cr, M n , Fe, N i a n d Pb. Z i n c ( 3 0 - 3 0 0 0 p.p.m.) d e c r e a s e d t h e a b s o r p t i o n . T h e a b s o r p t i o n a l m o s t d o u b l e d in the p r e s e n c e o f 10(~)10000 p.p.m, s t r o n t i u m . T h e a b s o r p t i o n increased with i n c r e a s i n g c o n c e n t r a t i o n s o f b a r i u m ; 10000 p . p . m , i n c r e a s e d t h e a b s o r p t i o n by 90%. C o p p e r u p to 300 p.p.m, h a d little effect b u t 1 0 0 0 - 1 0 0 0 0 p.p.m, i n c r e a s e d the a b s o r b a n c e by 4 0 - 5 0 % . A n a b s o r p t i o n increase o f 35% w a s c a u s e d by 300 p.p.m, a l u m i n u m b u t a d e c r e a s e o f 70% was c a u s e d by 10000 p.p.m. T h e a b s o r p t i o n o f d y s p r o s i u m d e c r e a s e d by 2 5 - 7 5 % in t h e p r e s e n c e o f 1000-10000 p.p.m, o f Li, N a , K, M g , Ca, Sr, Ba a n d Cr. T h e p r e s e n c e o f 3 0 0 0 - 1 0 0 0 0 p.p.m, m a n g a n e s e or lead i n c r e a s e d the a b s o r p t i o n by 20--40%. I r o n , nickel, c o p p e r a n d zinc u p to 10000 p.p.m, h a d little effect. T h e a b s o r p t i o n inc r e a s e d by 2 5 - 4 0 % in t h e p r e s e n c e o f 100-300 p.p.m, of a l u m i n u m , b u t d e c r e a s e d by 65~,~ in t h e p r e s e n c e o f 10000 p . p . m . The absorption of terbium and dysprosium increased with increasing conc e n t r a t i o n s o f o t h e r r a r e - e a r t h e l e m e n t s . T h e p r e s e n c e o f 3000 p.p.m, o f t h e s e i n c r e a s e d t h e a b s o r p t i o n o f t e r b i u m by 7 0 - 1 0 0 % a n d t h a t o f d y s p r o s i u m by 50-80%. As s h o w n in Fig. 4, t h e effects o f t h e o t h e r rare e a r t h s o n t h e a b s o r p t i o n o f t e r b i u m a n d d y s p r o s i u m were m a i n l y classified w i t h i n t h r e e g r o u p s .
Effects of organic solvents T h e effects o f a l c o h o l s o n t h e a b s o r p t i o n o f t e r b i u m (300 p.p.m.) a n d
346
T. ISHIZUKA, H. S U N A H A R A (b)
0.20
0.20
0.15
o~
0.15
g
o
z~
..=..a
0.10
0.10
T° JO
<~ 0.05
0.05
~ "
1
b
i
Added
O20
1000
metal
I
100(0)
0
ion c o n c n . , p . p . m .
I
!
i
qcx)
1000
10000
(d).
0.20
Dy
0.10
I
10
"Added metal concn.,p.pm.
(c)
0.15
g
I
100
~
g
0.15
Dy
~
g
:
0.05
.a: 0.05
~-% ~ 1
0
Added
, 100
, 1000
, 10000
m e t a l cohen., p.p.m.
0
m %
0
i
i
10
100
i
1000
I
10000
Added metal concn.,p.p.m.
Fig. 3. Effects of common metal ions on the absorption of terbium and dysprosium. Tb conch. 300 p.p.m.; Dy conch. 100 p.p.m, a: (C)) Li, ( A ) Na, (I-1) K. b: ( O ) Mg, ( A ) Ca, (r-7) Sr, ( O ) Ba, c: ( O ) Fe, ( A ) Ni, (I-1) Cu, (O) Zn. d: (C)) Cr, ( A ) Mn, (r-l) Pb, (O) AI.
~ c ~
Lo,Pr, Nd, Srn0 Eu Y, E r , T m
lobo
106oo
0.20
0.15
8 t-, o <¢
0.10
JO
0.05
o
A d d e d m e t a l i o n c o n c h . , p.p.m.
Fig. 4. Effects of rare-earth elements on the absorption of terbium and dysprosium. Tb cohen. 300 p.p.m.; DY conch. 100 p.p.m.
T E R B I U M A N D D Y S P R O S I U M BY A.A.S.
347
TABLE II EFFECTS OF ALCOHOLS ON THE ABSORPTION OF TERBIUM AND DYSPROSIUM
Solvent (v/v %)
Aqueous M e t h a n o l 40 80 95 Ethanol 40 80 95 P r o p a n o l 40 80 95 •
Absorption ratio Terbium
Dysprosium
1.00 1.03 1.82 1.95 0.92 1.52 2.01 1.15 1.29 1.55
1.00 0.80 1.77 2.58 0.69 1.42 2.19 0.91 1.05 1.39
d y s p r o s i u m (100 p.p.m.) w e r e investigated. M e t h a n o l , e t h a n o l a n d p r o p a n o l were u s e d in a m o u n t s o f 40, 80 a n d 95% in v o l u m e . T a b l e II s h o w s t h a t the p r e s e n c e o f 4 0 % a l c o h o l t e n d e d to d e c r e a s e t h e a b s o r p t i o n , p a r t i c u l a r l y for d y s p r o s i u m , w h e r e a s 8 0 % - 9 5 % a l c o h o l i c s o l u t i o n s c a u s e d m a r k e d increases for b o t h metals.
Calibration curves
C a l i b r a t i o n c u r v e s for t e r b i u m in t h e r a n g e 0 - 1 0 0 0 p.p.m, a n d d y s p r o s i u m in t h e r a n g e 0 - 2 0 0 p.p.m, are s h o w n in Figs. 5 a n d 6. C u r v e s w e r e p r e p a r e d f o r t e r b i u m o r d y s p r o s i u m alone, a n d for t e r b i u m o r d y s p r o s i u m w i t h a d d i t i o n o f 1% p o t a s s i u m , 1% y t t r i u m , or 1% l a n t h a n u m . T h e c a l i b r a t i o n curve for t e r b i u m a l o n e (Fig. 5) was c o n c a v e in t h e r a n g e 0 - 4 0 0 p.p.m, a n d convex in Ob Q4 Q3
o 3 ~ }o2 8 =
Q2
~ !
0
200
400
600
I
800
T b concn., p.p,m.
0.1
!
1000
0
4b
8b Oy
1/o
1, o
concn., p.p.m.
Fig. 5. C a l i b r a t i o n curves for terbium. ( Q ) Tb alone, ( O ) Tb-t21% K , ( A ) T b + l ~ / o Y, (;-1) T b + l % La. Fig. 6. C a l i b r a t i o n curves for dysprosium. ( O ) D y alone, ( O ) D y + l % D y + 1% La.
K, ( A )
D y + l ~ / o Y, (I-1)
348
T. I S H I Z U K A .
H. S U N A H A R A
the range 8 0 0 - 1 0 0 0 p.p.m.; the sensitivity was increased by addition o f potassium, yttrium o r lanthanum, the curves b e c o m i n g linear in the range 0 - 6 0 0 p.p.m., but still b e n d i n g slightly in the range 6 0 0 - 1 0 0 0 p.p.m.. T h e cafibration curve for dysprosium alone (Fig. 6) was linear in the range 0 - 2 0 0 p.p.m.; the additives increased the sensitivity but greatly decreased the linear range.
Analysis o f synthetic samples Samples c o n t a i n i n g v a r i o u s - a m o u n t s o f terbium and d y s p r o s i u m oxides were m a d e up w i t h yttria as s h o w n in Table III. The total c o n c e n t r a t i o n o f Tb4OT, DY2Oa and Y2Oa in each sample solution w a s 1 g/100 ml. S a m p l e s o l u t i o n s c o n t a i n i n g high c o n c e n t r a t i o n s o f terbium or dysprosium were diluted to an appropriate c o n c e n t r a t i o n for the a t o m i c a b s o r p t i o n measurements, and 19/o o f p o t a s s i u m ion w a s added to this solution for b o t h terbium and dysprosium. T h e results o b t a i n e d are s h o w n in Table III. The values found for terbium in TABLE
III
RESULTS
Sample no.
FOR
TERBIUM
DYSPROSIUM
IN SYNTHETIC
T b 4 0 7 concn.
Theore-
SAMPLES"
D Y 2 0 a conch.
Found
tical
1 2 3 4 5 6
AND
(%)
(%)
30.0 10.0 3.0 1.0 0.3 0.1
29.2 10.5 3.10 0.96 0.31 --
Relative
Theore-
error
tical
(%)
(%)
+2.7 +5.0 +3.3 --4.0 -3.3 --
0.1 0.3 1.0 3.0 10.0 30.0
0.t0 0.31 0.97 2.85 10.3 30.3
(%)
Found
Relative error
(%)
0 +3.3 --3.0 +5.0 +3.0 +1.0
" S a m p l e c o m p o s i t i o n : the a m o u n t s o f T b 4 0 7
and D y 2 O a taken are given in c o l u m n s 2 a n d 5 o f the Table; in all cases, the c o m p o s i t i o n was m a d e up to 100% with Y 2 0 3.
TABLE
IV
RESULTS
S a m p l e no.
1 2 3 4 5
FOR
TERBIUM
AND
DYSPROSIUM
T b 4 0 7 conch.
IN SAMPLES
OF
RARE-EARTH
D Y 2 0 a conch.
Conch.
s,
by FE b
Collcn.
s,
by FE b
(%)
(%)
(%)
(%)
(%)
(0.4)
1.27 0.76 --0.41
6.0 6.0 --4.9
1.38 0.94 --0.33
3.98 2.36 0.71 0.04 0t.58
2.7 1.2 2.3 6.6 4.1
4.08 2.45 0.74 0.04 0.61
E a c h value is the m e a n o f 5 determinations. b Values measured by a flame e m i s s i o n m e t h o d .
OXIDES a
T E R B I U M A N D D Y S P R O S I U M BY A.A.S.
349
the r a n g e 0.3-30.09/o Tb,,O7 h a d a relative e r r o r o f + 5 . 0 to --4.09/0 c o m p a r e d to the theoretical values; 0.19/o T b , O7 c o u l d n o t be d e t e r m i n e d accurately. T h e values f o u n d for d y s p r o s i u m in the r a n g e 0.1-30.09/o D y 2 0 3 h a d a relative e r r o r of + 5.0 to --3.09/0 c o m p a r e d t o the t h e o r e t i c a l values.
Analysis o f rare-earth oxides T e r b i u m a n d d y s p r o s i u m w e r e d e t e r m i n e d in practical samples o f raree a r t h oxides (a c r u d e grade" m a t e r i a l u s e d in an ion-exchange s e p a r a t i o n process). T h e r a r e earth oxides (1 g) were dissolved in h y d r o c h l o r i c acid, a n d diluted ..... to a v o l u m e o f 100 ml. T h e results ( T a b l e IV) are c o n s i d e r e d to be satisfactory, a n d are in g o o d a g r e e m e n t with .results o b t a i n e d by a flame-emission method. SUMMARY
F o r the d e t e r m i n a t i o n o f t e r b i u m a n d d y s p r o s i u m by a t o m i c a b s o r p t i o n s p e c t r o m e t r y , the effects o f several i n o r g a n i c acids, metal ions a n d alcohols were studied. T h e two m e t a l s were d e t e r m i n e d in the presence o f yttria a n d in raree a r t h oxides with satisfactory results. RI~SUMI~
U n e 6tude est effectu6e sur la s p e c t r o m 6 t r i e par a b s o r p t i o n a t o m i q u e d u t e r b i u m et d u d y s p r o s i u m . O n e x a m i n e l'influence de divers acides inorganiques, de divers ions m~talliques et des alcools. Les dosages de ces deux m 6 t a u x o n t d o n n ~ des r6sultats satisfaisants, en pr6sence d ' o x y d e d ' y t t r i u m et d ' o x y d e s de terres rares. ZUSAM MENFASSUNG
D e r Einfluss v o n v e r s c h i e d e n e n a n o r g a n i s c h e n Siiuren, M e t a l l i o n e n u n d A l k o h o l e n auf d i e B e s t i m m u n g v o n T e r b i u m u n d D y s p r o s i u m d u r c h A t o m a b s o r p t i o n s s p e k t r o m e t r i e w u r d e u n t e r s u c h t . D i e beiden Metalle k o n n t e n in G e g e n w a r t y o n Y t t r i u m o x i d u n d in S e l t e n e r d - O x i d e n mit zufriedenstellenden Ergebnissen b e s t i m m t werden. REFERENCES 1 2 3 4 5 6 7 8
V. G. Mossotti and V. A. Fassei, Spectrochim. Acta, 20 (1964) I 117. M. D. Amos and J. B. Willis. Spectrochim. Acta, 22 (1966) 1325. D. C. Manning, At. Absorpt. Newsl., 5 (1966) 127. J. K i n n u n e n and O. Lidsjo, Chem. Anal., 56 (1967) 25. R. J. Jaworowski, R. P. Weberling a n d D. J. Bracco, Anal. Chim. Acta, 37 (1967) 284. J. C. V a n Loon, J. H. G a l b r a i t h a n d H. M. Aarden, Analyst° 96 (1971) 47. A. M. Szaplonczay, Analyst, 97 (1972) 29. Sh. (3. Melamed, A. M. Saltikova a n d L. F. Tchelidze, Zavod. Lab., 37 (1971) 166.