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Determination of manganese by electrothermal atomisation atomic absorption spectrometry following coprecipitation with yttrium hydroxide
ANALYTICA CHIMICA AC-IA ELSEVIER
Analytica
Chimica Acta 298 (1994) 375-379
Determination of manganese by electrothermal atomisation atomic absorption spectrometry following coprecipitation with yttrium hydroxide Kikuo Takeda *, Chikashi Akamatsu, Yoshihiro Ishikawa Ehime Research Laboratory,
Sumitomo Chemical Co., Ltd., 5-1, Soubiraki-cho,
Niihamu, Ehime 792, Japan
Received 5 June 1994
Abstract Coprecipitation is applied to the determination of trace amounts of manganese by electrothermal atomisation atomic absorption spectrometry. Manganese (0.05-l pg) is coprecipitated quantitatively from the sample solution (50-500 ml) with yttrium hydroxide at pH 9.0-11.3. The atomic absorbance of manganese is increased about 3 times by using an
yttrium-impregnated graphite cuvette. The calibration curve is linear from 0.002 to 0.04 pg rnlll of manganese. Twenty-three different ions investigated did not produce serious interferences. The proposed method was successfully applied to the determination of trace amounts of manganese in zinc metal. Keywords:
Atomic absorption
spectrometry;
Coprecipitation;
Electrothermal
1. Introduction Preconcentration procedures utilizing the collection of trace elements by coprecipitation have often been used to improve the sensitivity and/or selectivity of a given analytical method. Their major advantage over other preconcentration techniques lies in simplicity. Moreover, relatively high enrichment factors can be achieved. A variety of coprecipitants for the concentration of manganese have been proposed, including metal hydroxides [l-17], sulphide [l&l,
* Corresponding author. Present address: Sumika Chemical Analysis Service, Ltd., 3-l-43, Shinden-cho, Niihama, Ehime 792, Japan. 0003-2670/94/$07.00 0 1994 Elsevier Science B.V. All rights reserved SSDI 0003-2670(94)00294-O
AAS; Manganese
phosphate [19], and organic precipitants [20-281. For preconcentration prior to the determination of manganese by atomic absorption spectrometry (AAS) using graphite tube atomisation, indium hydroxide has recently been reported [29]. In a previous paper [30], the present authors proposed that yttrium hydroxide was effective as a collector for trace amounts of tin. In this work, we used yttrium hydroxide as a coprecipitant for manganese prior to the determinatidn by electrothermal atomisation AAS. It was found that yttrium hydroxide could quantitatively collect trace amounts of Furthermore, the presence of yttrium manganese. enhanced the atomic absorbance of manganese in the determination of manganese by electrothermal atomisation MS.
376
K. Takeda et al. /Analytica Chimica Acfa 298 (1994) 375-379
2. Experimental
Table 1 Instrumental
2. I. Apparatus
Analytical wavelength Slit width Lamp current Argon flow rate Carrier gas Interrupted gas Injection volume Cuvette Furnace programme Drying Ashing Atomisation
A Hitachi Z-7000 Zeeman-effect atomic absorption spectrophotometer equipped with a manganese hollow-cathode lamp (Hitachi 2082019-21) was used for the atomic absorption measurements. A Horiba M-8S glass electrode pH meter was utilized for pH measurements. Glass material was previously washed with hydrochloric acid and deionized water to prevent trace contamination.
conditions
for the determination
of manganese
279.6 nm 0.4 nm 7.5 mA 200 ml min ’ 30 ml min-’ 10 /_Ll Yttrium-impregnated
graphite tube
80-12O”C, 30 s SOO”C, 30 s 25OO”C, 10 s
2.2. Reagents All reagents were of analytical-reagent grade and deionized water prepared with a Mini-Q system (Millipore) was used throughout. A stock solution of manganese (1 mg ml-‘) was prepared by dissolving 0.360 g of manganese(I1) chloride tetrahydrate (Wako) in 0.02 M hydrochloric acid and diluting the solution to 100 ml with deionized water. An yttrium solution (10 mg ml-‘) was prepared by dissolving 1.270 g of yttrium oxide (Wako, 99.99%) in small amounts of nitric acid and diluting the solution to 100 ml with deionized water. 2.3. Impregnation
of cuvette
Tube-type graphite cuvettes were employed throughout this study. A 20 ,~l aliquot of an yttrium solution (10 mg ml- * ) was placed in a new graphite cuvette and carried through the atomisation cycle given for the measurements of manganese. This step was repeated three times. 2.4. General procedure A l-ml volume of an yttrium solution (10 mg ml-‘) is added to a sample solution (50-500 ml) containing 0.05-l pg of manganese. The pH of the solution is adjusted to about 10.5 with aqueous ammonia. To let the yttrium hydroxide settle, the solution is allowed to stand for more than 1 h. The precipitate is filtered by suction using a 3G4 sintered-glass filter, washed with small amounts of deionized water and dissolved with 5 ml of 3 M
nitric acid. After the solution is diluted to 25 ml with deionized water, manganese is determined by electrothermal atomisation AAS using an yttrium-imconditions for pregnated cuvette. The operating atomic absorption measurements are shown in TabIe 1. A blank is also run, using deionized water instead of the sample solution.
3. Results and discussion 3.1. Enhancing e#ect
ofyttrium
The enhancing effect of yttrium on the atomic absorbance of manganese was investigated with untreated graphite cuvettes by measuring the response of manganese solution in the to 0.02 pg ml-l presence of 0.4 mg ml-l yttrium and in the absence of yttrium. In the presence of yttrium, it was observed that the atomic absorbance of manganese gradually increased with injection times and reached almost constant absorbance. This value was almost equal to the atomic absorbance of manganese measured using yttrium-impregnated graphite cuvettes. The enhancement factor was about 3 as shown in Fig. 1. This phenomenon can be explained as the enhancing effect by formation of yttrium carbide on the inner surfaces of the graphite cuvettes such as the impregnation of graphite surfaces with lanthanum or zirconium [31]. For these results, we decided to use the yttrium-impregnated graphite cuvettes for sensitive measurements of the atomic absorbance of manganese.
K. Tukeda et al./Analytica
Chimica Acta 298 (19941375-379
377
0.3 -
d : e a z m
0.2 -
0
0.02
0.04
0.1 Acid
Manganese
Fig. 1. presence cuvette graphite
(ug
ml-’
)
Response-concentration graphs for manganese in the of 0.4 mg ml-’ of yttrium with an yttrium-impregnated (A) and in the absence of yttrium with an untreated cuvette (B).
3.2. Optimum conditions
for measurements
The optimum operating conditions for the determination of manganese by electrothermal atomisation AAS with the yttrium-impregnated graphite cuvette were investigated. The effect of the concentration of nitric, hydrochloric and sulphuric acid on the atomic absorbance of 0.02 pg ml-l of manganese was examined. In the range 0.1-l M of nitric acid, 0.1-3 M of hydrochloric acid and 0.1-I M of sulphuric acid, the atomic absorbance of manganese was almost constant. At higher concentrations of these acids, the atomic absorbance gradually decreased. The results are shown in Fig. 2. In further experiments, 0.6 M nitric acid was used. The heating programme for the drying, ashing and atomisation stages was examined by using 0.6 M nitric acid solution containing 0.02 pug ml-’ of manganese and 0.4 mg ml ’ of yttrium. A setting of 80-12O”C/30 s was sufficient for drying. At the ashing stage, the atomic absorbance of manganese was almost constant from 400 to llOO”C, and then decreased steeply at higher temperature. The results are shown in Fig. 3, together with those by using an untreated graphite cuvette and the manganese solution (0.02 pg ml-‘) not containing yttrium. With an increase in the atomisation temperature, the atomic
10
1
(mol dmm3 )
Fig. 2. Influence of hydrochloric acid (‘A), nitric acid (B) and sulphuric acid (C) on the atomic absorbance of manganese.
absorbance of manganese increased and remained almost constant for temperatures of more than 1900°C. The results are shown in Fig. 4, together with those by using an untreated graphite cuvette in the absence of yttrium. The optimum instrumental parameters are summarized in Table 1. 3.3. Efiect of pH on coprecipitation To determine the optimum tion with yttrium hydroxide,
pH of the coprecipitathe recovery of man-
I
I
I
600
1200
1600
Temperature
1
2000
(“c)
Fig. 3. Effect of the ashing temperature examined with 0.6 M nitric acid solution containing 0.02 pg ml-’ of manganese, in the presence of 0.4 mg ml-’ of yttrium with an impregnated graphite cuvette (A), and in the absence of yttrium with an untreated graphite cuvette (B).
378
K. Takedu et al. /AnaZytica
C&mica Acta 298 (1994) 37.5-379
while standing for 6 h. From these results, the precipitate was allowed to stand for more than 1 h. 3.6. Calibration
//-K-r-
y
*’
I
I
1600
2000 Temperature
I
2400
I
2800
(“C)
Fig. 4. Effect of the atomisation temperature examined with 0.6 M nitric acid solution containing 0.02 pg ml-’ of manganese, in the presence of 0.4 mg mI- ’ of yttrium with an impregnated graphite cuvette (A), and in the absence of yttrium with an untreated graphite cuvette (B).
ganese was studied in the pH range 8.4-11.3 with the solutions (100 ml) containing 0.5 lug of manganese, according to the general procedure. The results indicated that maximum and almost constant recoveries were obtained at pH 9.0-11.3. The pH was therefore adjusted to about 10.5 for the coprecip itation. 3.4. Effect of amounts of coprecipitunt The necessary amounts of yttrium for the coprecipitation were examined with solutions (100-500 ml) containing 0.5 pg of manganese. More than 3 mg of yttrium should be added to 100 ml of the solutions for quantitative collection. This amount shouId increase to 5 mg, when the volume of sample solution increased to 500 ml. From these results, an yttrium amount of 10 mg was used for the coprecipitation. 3.5. Effect of standing time The relation between the recovery of 0.5 pg of manganese and the standing time of the precipitate was investigated. The recovery of manganese was almost 100% at about 1 h after the formation of yttrium hydroxide and remained almost constant
curue
A straight line was obtained over the concentration range of 0.002-0.04 ,~g ml-’ of manganese. The reproducibility, expressed by the relative standard deviation obtained from ten repeated determinations, was 4.2% for 0.02 pg ml-’ of manganese. The detection limit, defined as three times the standard deviation for 20 measurements of the reagent blank, was 0.7 ng ml -I of manganese if a volume of 10 ~1 was taken. 3.7. Interferences The influence of 23 different ions on the determination of 0.5 Fg of manganese was examined by coprecipitating manganese from about 100 ml of sample solution. Aluminium(III), Si(IV), Ti(IV), V(V), Fe(III), Co(II), Ni(II), C&I), Z&I), Ga(III), S&I), Sb(III), Ba(II), Pb(II), Bi(III), Cl-, NO;, SO:-, and PO:did not interfere in a 2000-fold amount relative to manganese, within 5% relative error values. Na, Mg, K, and Ca did not interfere even in lOO,OOO-fold excess. 3.8. Application in zinc metal
to the determination
of manganese
To evaluate the usefulness of the proposed method, the determination of manganese in zinc matal was carried out. The sample (0.5 g) was dissolved in a mixture of 20 ml of hydrochloric acid and 0.1 ml of nitric acid. The resulting solution was diluted to 100 ml with deionized water and treated according to the general procedure. The sample solu-
Table 2 Analytical
results of manganese
in zinc metal (0.5 g> and recovery
Added ( pg)
Found ( pg) a
Recovery (%)
0.10 0.25 0.50
0.07 0.17 0.33 0.55
100 104 96
a The mean of triplicate measurements.
_
K. Takeda et al. /Analytica Chimica Acta 298 (I9941 375-379
tions spiked with manganese were also examined. The results obtained are shown in Table 2. From these results, it was found that the proposed method is applicable to the concentration and determination of trace amounts of manganese in zinc metal.
379
[9] T. Akagi and H. Haraguchi, Anal. Chem., 62 (1990) 81. [lo] E. Bruninx, A.V. Eenbergan and A. Schouten, Anal. Chim. Acta, 109 (1979) 419. [ll] H. Yoshikawa, K. Isobe, H. Iwata, N. Benitani, K. Saito and H. Seno, Bunseki Kagaku, 38 (1989) 535. [12] F. Koroleff, Acta Chem. Stand., 1 (1947) 503. [13] Y. Shigetomi, Bunseki Kagaku, 24 (1975) 699. [14] A. Tsuyama and S. Nakashima, Bunseki Kagaku, 29 (1980)
4. Conclusion A quantitative method for the preconcentration of trace amounts of manganese has been developed. Coprecipitation with yttrium hydroxide was suitable for preconcentration prior to the determination of manganese by electrothermal atomisation AAS. The use of an yttrium-impregnated graphite cuvette increased the atomic absorbance of manganese. The present method was useful for the determination of manganese in zinc metal.
References [l] P.N.W. Young, Analyst, 99 (1974) 588. [2] Y. Harada and N. &rata, Bunseki Kagaku, 35 (1986) 641. [3] M. Hiraide, Y. Yoshida and A Mizuike, Anal. Chim. Acta, 81 (1976) 185. [4] R. Ko and P. Anderson, Anal. Chem., 41 (1969) 177. [S] J.M. Scarborough, CD. Bingham and P.F. DeVries, Anal. Chem., 39 (1967) 1394. [6] Y. Harada, N. Kurata and G. Furuno, Bunseki Kagaku, 36 (1987) 526. [7] K. Himeno, K. Yanagisawa, T. Yuki and Y. Nakamura, Bunseki Kagaku, 33 (1984) T43. [8] T. Akagi, K. Fuwa and H. Haraguchi, Anal. Chim. Acta, 177 (1985) 139.
[15] Es. Buchanan and P. Hannaker, Anal. Chem., 56 (1984) 1379. [16] H.L. Polak, J. Radioanal. Chem., 9 (1971) 241. [17] Y. Harada, Bunseki Kagaku, 31 (1982) 130. [18] V. Sirneonov, I. Karadzhova and S. Aleksandrov, Fresenius’ Z. Anal. Chem., 320 (1985) 330. [19] J. Holzbecher and D.E. Ryan, J. Radioanal. Chem., 74 (1982) 25. [20] S. Brueggerhoff and E. Jackwerth, Fresenius’ Z. Anal. Chem., 326 (1987) 528. [21] H. Bern and D.E. Ryan, Anal. Chim. Acta, 166 (1984) 189. [22] H. Watanabe, S. Berman and D.S. Russell, Talanta, 19 (1972) 1363. [23] E. Yamada and M. Sato, Bunseki Kagaku, 32 (1983) 654. [24] C. Bergerioux and W. Haerdi, Analusis, 8 (1980) 169. [25] W. Zmijetiska, H. Polkowska-Motrenko and H. Stokowska, J. Radioanal. Nucl. Chem., 84 (1984) 319. [26] J.M. Eckert, K.E.A. Leggett, J.B. Keene and K.L. Williams, Anal. Chim. Acta., 222 (1989) 169. [27] I. Atsuya and K. Itoh, Fresenius’ Z. Anal. Chem., 329 (1988) 750. [Z&I K. Akatsuka and I. Atsuya, Anal. Chim. Acta, 202 (1987) 223. [29] M. Hiraide, Z.-S. Chen and H. Kawaguchi, Anal. Sci., 7 (1991) 65. [30] K. Takeda, C. Akamatsu and Y. Inoue, Fresenius’ J. Anal. Chem., 339 (1991) 50. [31] J.H. Rurmels, R. Merryfield and H.B. Fisher, Anal. Chem., 47 (1975) 1258.
Analytica
Chimica Acta 298 (1994) 375-379
Determination of manganese by electrothermal atomisation atomic absorption spectrometry following coprecipitation with yttrium hydroxide Kikuo Takeda *, Chikashi Akamatsu, Yoshihiro Ishikawa Ehime Research Laboratory,
Sumitomo Chemical Co., Ltd., 5-1, Soubiraki-cho,
Niihamu, Ehime 792, Japan
Received 5 June 1994
Abstract Coprecipitation is applied to the determination of trace amounts of manganese by electrothermal atomisation atomic absorption spectrometry. Manganese (0.05-l pg) is coprecipitated quantitatively from the sample solution (50-500 ml) with yttrium hydroxide at pH 9.0-11.3. The atomic absorbance of manganese is increased about 3 times by using an
yttrium-impregnated graphite cuvette. The calibration curve is linear from 0.002 to 0.04 pg rnlll of manganese. Twenty-three different ions investigated did not produce serious interferences. The proposed method was successfully applied to the determination of trace amounts of manganese in zinc metal. Keywords:
Atomic absorption
spectrometry;
Coprecipitation;
Electrothermal
1. Introduction Preconcentration procedures utilizing the collection of trace elements by coprecipitation have often been used to improve the sensitivity and/or selectivity of a given analytical method. Their major advantage over other preconcentration techniques lies in simplicity. Moreover, relatively high enrichment factors can be achieved. A variety of coprecipitants for the concentration of manganese have been proposed, including metal hydroxides [l-17], sulphide [l&l,
* Corresponding author. Present address: Sumika Chemical Analysis Service, Ltd., 3-l-43, Shinden-cho, Niihama, Ehime 792, Japan. 0003-2670/94/$07.00 0 1994 Elsevier Science B.V. All rights reserved SSDI 0003-2670(94)00294-O
AAS; Manganese
phosphate [19], and organic precipitants [20-281. For preconcentration prior to the determination of manganese by atomic absorption spectrometry (AAS) using graphite tube atomisation, indium hydroxide has recently been reported [29]. In a previous paper [30], the present authors proposed that yttrium hydroxide was effective as a collector for trace amounts of tin. In this work, we used yttrium hydroxide as a coprecipitant for manganese prior to the determinatidn by electrothermal atomisation AAS. It was found that yttrium hydroxide could quantitatively collect trace amounts of Furthermore, the presence of yttrium manganese. enhanced the atomic absorbance of manganese in the determination of manganese by electrothermal atomisation MS.
376
K. Takeda et al. /Analytica Chimica Acfa 298 (1994) 375-379
2. Experimental
Table 1 Instrumental
2. I. Apparatus
Analytical wavelength Slit width Lamp current Argon flow rate Carrier gas Interrupted gas Injection volume Cuvette Furnace programme Drying Ashing Atomisation
A Hitachi Z-7000 Zeeman-effect atomic absorption spectrophotometer equipped with a manganese hollow-cathode lamp (Hitachi 2082019-21) was used for the atomic absorption measurements. A Horiba M-8S glass electrode pH meter was utilized for pH measurements. Glass material was previously washed with hydrochloric acid and deionized water to prevent trace contamination.
conditions
for the determination
of manganese
279.6 nm 0.4 nm 7.5 mA 200 ml min ’ 30 ml min-’ 10 /_Ll Yttrium-impregnated
graphite tube
80-12O”C, 30 s SOO”C, 30 s 25OO”C, 10 s
2.2. Reagents All reagents were of analytical-reagent grade and deionized water prepared with a Mini-Q system (Millipore) was used throughout. A stock solution of manganese (1 mg ml-‘) was prepared by dissolving 0.360 g of manganese(I1) chloride tetrahydrate (Wako) in 0.02 M hydrochloric acid and diluting the solution to 100 ml with deionized water. An yttrium solution (10 mg ml-‘) was prepared by dissolving 1.270 g of yttrium oxide (Wako, 99.99%) in small amounts of nitric acid and diluting the solution to 100 ml with deionized water. 2.3. Impregnation
of cuvette
Tube-type graphite cuvettes were employed throughout this study. A 20 ,~l aliquot of an yttrium solution (10 mg ml- * ) was placed in a new graphite cuvette and carried through the atomisation cycle given for the measurements of manganese. This step was repeated three times. 2.4. General procedure A l-ml volume of an yttrium solution (10 mg ml-‘) is added to a sample solution (50-500 ml) containing 0.05-l pg of manganese. The pH of the solution is adjusted to about 10.5 with aqueous ammonia. To let the yttrium hydroxide settle, the solution is allowed to stand for more than 1 h. The precipitate is filtered by suction using a 3G4 sintered-glass filter, washed with small amounts of deionized water and dissolved with 5 ml of 3 M
nitric acid. After the solution is diluted to 25 ml with deionized water, manganese is determined by electrothermal atomisation AAS using an yttrium-imconditions for pregnated cuvette. The operating atomic absorption measurements are shown in TabIe 1. A blank is also run, using deionized water instead of the sample solution.
3. Results and discussion 3.1. Enhancing e#ect
ofyttrium
The enhancing effect of yttrium on the atomic absorbance of manganese was investigated with untreated graphite cuvettes by measuring the response of manganese solution in the to 0.02 pg ml-l presence of 0.4 mg ml-l yttrium and in the absence of yttrium. In the presence of yttrium, it was observed that the atomic absorbance of manganese gradually increased with injection times and reached almost constant absorbance. This value was almost equal to the atomic absorbance of manganese measured using yttrium-impregnated graphite cuvettes. The enhancement factor was about 3 as shown in Fig. 1. This phenomenon can be explained as the enhancing effect by formation of yttrium carbide on the inner surfaces of the graphite cuvettes such as the impregnation of graphite surfaces with lanthanum or zirconium [31]. For these results, we decided to use the yttrium-impregnated graphite cuvettes for sensitive measurements of the atomic absorbance of manganese.
K. Tukeda et al./Analytica
Chimica Acta 298 (19941375-379
377
0.3 -
d : e a z m
0.2 -
0
0.02
0.04
0.1 Acid
Manganese
Fig. 1. presence cuvette graphite
(ug
ml-’
)
Response-concentration graphs for manganese in the of 0.4 mg ml-’ of yttrium with an yttrium-impregnated (A) and in the absence of yttrium with an untreated cuvette (B).
3.2. Optimum conditions
for measurements
The optimum operating conditions for the determination of manganese by electrothermal atomisation AAS with the yttrium-impregnated graphite cuvette were investigated. The effect of the concentration of nitric, hydrochloric and sulphuric acid on the atomic absorbance of 0.02 pg ml-l of manganese was examined. In the range 0.1-l M of nitric acid, 0.1-3 M of hydrochloric acid and 0.1-I M of sulphuric acid, the atomic absorbance of manganese was almost constant. At higher concentrations of these acids, the atomic absorbance gradually decreased. The results are shown in Fig. 2. In further experiments, 0.6 M nitric acid was used. The heating programme for the drying, ashing and atomisation stages was examined by using 0.6 M nitric acid solution containing 0.02 pug ml-’ of manganese and 0.4 mg ml ’ of yttrium. A setting of 80-12O”C/30 s was sufficient for drying. At the ashing stage, the atomic absorbance of manganese was almost constant from 400 to llOO”C, and then decreased steeply at higher temperature. The results are shown in Fig. 3, together with those by using an untreated graphite cuvette and the manganese solution (0.02 pg ml-‘) not containing yttrium. With an increase in the atomisation temperature, the atomic
10
1
(mol dmm3 )
Fig. 2. Influence of hydrochloric acid (‘A), nitric acid (B) and sulphuric acid (C) on the atomic absorbance of manganese.
absorbance of manganese increased and remained almost constant for temperatures of more than 1900°C. The results are shown in Fig. 4, together with those by using an untreated graphite cuvette in the absence of yttrium. The optimum instrumental parameters are summarized in Table 1. 3.3. Efiect of pH on coprecipitation To determine the optimum tion with yttrium hydroxide,
pH of the coprecipitathe recovery of man-
I
I
I
600
1200
1600
Temperature
1
2000
(“c)
Fig. 3. Effect of the ashing temperature examined with 0.6 M nitric acid solution containing 0.02 pg ml-’ of manganese, in the presence of 0.4 mg ml-’ of yttrium with an impregnated graphite cuvette (A), and in the absence of yttrium with an untreated graphite cuvette (B).
378
K. Takedu et al. /AnaZytica
C&mica Acta 298 (1994) 37.5-379
while standing for 6 h. From these results, the precipitate was allowed to stand for more than 1 h. 3.6. Calibration
//-K-r-
y
*’
I
I
1600
2000 Temperature
I
2400
I
2800
(“C)
Fig. 4. Effect of the atomisation temperature examined with 0.6 M nitric acid solution containing 0.02 pg ml-’ of manganese, in the presence of 0.4 mg mI- ’ of yttrium with an impregnated graphite cuvette (A), and in the absence of yttrium with an untreated graphite cuvette (B).
ganese was studied in the pH range 8.4-11.3 with the solutions (100 ml) containing 0.5 lug of manganese, according to the general procedure. The results indicated that maximum and almost constant recoveries were obtained at pH 9.0-11.3. The pH was therefore adjusted to about 10.5 for the coprecip itation. 3.4. Effect of amounts of coprecipitunt The necessary amounts of yttrium for the coprecipitation were examined with solutions (100-500 ml) containing 0.5 pg of manganese. More than 3 mg of yttrium should be added to 100 ml of the solutions for quantitative collection. This amount shouId increase to 5 mg, when the volume of sample solution increased to 500 ml. From these results, an yttrium amount of 10 mg was used for the coprecipitation. 3.5. Effect of standing time The relation between the recovery of 0.5 pg of manganese and the standing time of the precipitate was investigated. The recovery of manganese was almost 100% at about 1 h after the formation of yttrium hydroxide and remained almost constant
curue
A straight line was obtained over the concentration range of 0.002-0.04 ,~g ml-’ of manganese. The reproducibility, expressed by the relative standard deviation obtained from ten repeated determinations, was 4.2% for 0.02 pg ml-’ of manganese. The detection limit, defined as three times the standard deviation for 20 measurements of the reagent blank, was 0.7 ng ml -I of manganese if a volume of 10 ~1 was taken. 3.7. Interferences The influence of 23 different ions on the determination of 0.5 Fg of manganese was examined by coprecipitating manganese from about 100 ml of sample solution. Aluminium(III), Si(IV), Ti(IV), V(V), Fe(III), Co(II), Ni(II), C&I), Z&I), Ga(III), S&I), Sb(III), Ba(II), Pb(II), Bi(III), Cl-, NO;, SO:-, and PO:did not interfere in a 2000-fold amount relative to manganese, within 5% relative error values. Na, Mg, K, and Ca did not interfere even in lOO,OOO-fold excess. 3.8. Application in zinc metal
to the determination
of manganese
To evaluate the usefulness of the proposed method, the determination of manganese in zinc matal was carried out. The sample (0.5 g) was dissolved in a mixture of 20 ml of hydrochloric acid and 0.1 ml of nitric acid. The resulting solution was diluted to 100 ml with deionized water and treated according to the general procedure. The sample solu-
Table 2 Analytical
results of manganese
in zinc metal (0.5 g> and recovery
Added ( pg)
Found ( pg) a
Recovery (%)
0.10 0.25 0.50
0.07 0.17 0.33 0.55
100 104 96
a The mean of triplicate measurements.
_
K. Takeda et al. /Analytica Chimica Acta 298 (I9941 375-379
tions spiked with manganese were also examined. The results obtained are shown in Table 2. From these results, it was found that the proposed method is applicable to the concentration and determination of trace amounts of manganese in zinc metal.
379
[9] T. Akagi and H. Haraguchi, Anal. Chem., 62 (1990) 81. [lo] E. Bruninx, A.V. Eenbergan and A. Schouten, Anal. Chim. Acta, 109 (1979) 419. [ll] H. Yoshikawa, K. Isobe, H. Iwata, N. Benitani, K. Saito and H. Seno, Bunseki Kagaku, 38 (1989) 535. [12] F. Koroleff, Acta Chem. Stand., 1 (1947) 503. [13] Y. Shigetomi, Bunseki Kagaku, 24 (1975) 699. [14] A. Tsuyama and S. Nakashima, Bunseki Kagaku, 29 (1980)
4. Conclusion A quantitative method for the preconcentration of trace amounts of manganese has been developed. Coprecipitation with yttrium hydroxide was suitable for preconcentration prior to the determination of manganese by electrothermal atomisation AAS. The use of an yttrium-impregnated graphite cuvette increased the atomic absorbance of manganese. The present method was useful for the determination of manganese in zinc metal.
References [l] P.N.W. Young, Analyst, 99 (1974) 588. [2] Y. Harada and N. &rata, Bunseki Kagaku, 35 (1986) 641. [3] M. Hiraide, Y. Yoshida and A Mizuike, Anal. Chim. Acta, 81 (1976) 185. [4] R. Ko and P. Anderson, Anal. Chem., 41 (1969) 177. [S] J.M. Scarborough, CD. Bingham and P.F. DeVries, Anal. Chem., 39 (1967) 1394. [6] Y. Harada, N. Kurata and G. Furuno, Bunseki Kagaku, 36 (1987) 526. [7] K. Himeno, K. Yanagisawa, T. Yuki and Y. Nakamura, Bunseki Kagaku, 33 (1984) T43. [8] T. Akagi, K. Fuwa and H. Haraguchi, Anal. Chim. Acta, 177 (1985) 139.
[15] Es. Buchanan and P. Hannaker, Anal. Chem., 56 (1984) 1379. [16] H.L. Polak, J. Radioanal. Chem., 9 (1971) 241. [17] Y. Harada, Bunseki Kagaku, 31 (1982) 130. [18] V. Sirneonov, I. Karadzhova and S. Aleksandrov, Fresenius’ Z. Anal. Chem., 320 (1985) 330. [19] J. Holzbecher and D.E. Ryan, J. Radioanal. Chem., 74 (1982) 25. [20] S. Brueggerhoff and E. Jackwerth, Fresenius’ Z. Anal. Chem., 326 (1987) 528. [21] H. Bern and D.E. Ryan, Anal. Chim. Acta, 166 (1984) 189. [22] H. Watanabe, S. Berman and D.S. Russell, Talanta, 19 (1972) 1363. [23] E. Yamada and M. Sato, Bunseki Kagaku, 32 (1983) 654. [24] C. Bergerioux and W. Haerdi, Analusis, 8 (1980) 169. [25] W. Zmijetiska, H. Polkowska-Motrenko and H. Stokowska, J. Radioanal. Nucl. Chem., 84 (1984) 319. [26] J.M. Eckert, K.E.A. Leggett, J.B. Keene and K.L. Williams, Anal. Chim. Acta., 222 (1989) 169. [27] I. Atsuya and K. Itoh, Fresenius’ Z. Anal. Chem., 329 (1988) 750. [Z&I K. Akatsuka and I. Atsuya, Anal. Chim. Acta, 202 (1987) 223. [29] M. Hiraide, Z.-S. Chen and H. Kawaguchi, Anal. Sci., 7 (1991) 65. [30] K. Takeda, C. Akamatsu and Y. Inoue, Fresenius’ J. Anal. Chem., 339 (1991) 50. [31] J.H. Rurmels, R. Merryfield and H.B. Fisher, Anal. Chem., 47 (1975) 1258.