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A new chemiluminescence reagent for the determination of ruthenium
Tahnfa, Vol. 41, No. 5, pp. 707-710, 1994 Copyright 0 1994 Elsevicr science Ltd
Printed in Great Britain. All rights reserved 0039-9140/94s7.00 + 0.00
A NEW CHEMILUMINESCENCE REAGENT FOR THE DETERMINATION OF RUTHENIUM ZHIKE HE, QINGYAOLuo, HUIMIN MA, XIMAOYu and YUN’ E ZENG Department of Chemistry, Wuhan University, Hubei, 430072, China (Received 9 July 1993. Revised 7 October 1993. Accepted 7 October 1993). Summary-A new reagent proflavine-N, N, N’, N’-tetraacetic acid (PTA) synthesized in our laboratory has been found useful as a chemiluminescence reagent for the determination of ruthenium (Ru) in pH 2.5 sulfuric acid solution containing acetone, it can be oxidized catalytically by hydrogen peroxide. With Ru(II1) as catalyst, it emits light selectively. The linear range is between 2.0 x lo-* and 2.0 x 10e5 g/ml. The detection limit and the recovery rate of the method are 1.0 x low9 g/ml and 96.~102%, respectively. The method has been satisfactorily applied to determine trace Ru(II1) in synthesized sample.
Ru is one of the precious metals. A number of methods for the determination of Ru have been reported, principally involving spectrophotometric methods.1*2 In recent years, some chemiluminescence (CL) methods for its determination have also been presented.%’ CL has the advantages of greater sensitivity, wider linear dynamic range and simpler instrtmrentation requirements compared to other methods such as ICP-AES8v9 But these CL system involving luminol have poor selectivity. Some of them, which linear dynamic ranges are often only one order of magnitude.3*4 With the use of Triton X-100, the detection limit of the method in Ref. 7 decreased nearly one order of magnitude compared to that in Ref. 6. But the determination of Ru in Au-G-Ru mixtures required that the Ru first be separated by reversed phase paper chromatograph with di-p-methyl phenyl sulfoxide as the stationary phase. Because the precious metals are rare in nature, the highly sensitive CL method is required to meet the needs of scientific research. Therefore the development of a new, highly sensitive and selective CL reagent is significant. Having tested a series of new fluorescent reagents, ‘Owe discovered that the determination of trace amount of Ru(II1) with proflavineJV,N,N’,N’-tetraacetic acid as a CL reagent is highly selective and without blank. This method can be directly applied to the determination of Ru(II1) in Au-O-Ru mixtures with satisfactory results.
EXPERIMENTAL Apparatus
CL meter, Model FG83-1 (Fuzhou radio No. 6 factory China), including photomultiplier tube and fused-silica reaction cell, and a type 3066 recorder (Sichuan instrumental general factory, China) were used. Reagents
A 0.5 mg/ml Ru(II1) stock-solution was prepared by weighing and dissolving 0.1644 g of [(NH,),Ru(H,O)Cl,] in warm hydrochloric acid of 2 mol/l,” and then diluting to 100 ml with water. Standard solution were obtained by diluting the stock solution with water. A 3.5 x 10e3 mol/l stock solution of PTA was prepared by weighing and dissolving 0.1545 g of PTA in some 2 mol/l sodium hydroxide and diluting to 100 ml with water. Hydrogen peroxide solution, 4.8%. Further diluted as required. All solutions were prepared from analytical grade chemicals and redistilled water. Procedure
A 1.0 ml portion of 3.5 x 10e3 mol/l PTA, 1.O ml of 0.6 mol/l sulfuric acid, 1.0 ml of 3.0 x 10m6 g/ml Ru(II1) and 1.0 ml of acetone were mixed in order in the reaction cell and then set in the black box. After 30 set, inject 1.0 ml of 4.8% hydrogen peroxide 707
HE ZHIKKet al.
708
RESULTS AND DISCUSSION
2
1
0 t NW
Fig. 1. Kinetic curve of PTA CL light emission; 3.0 pg/mI Ru(III), pH 2.5.
solution and record the signal at the same time (see Fig. 1). Synthesis of CL reagent PTA. PTA was synthesized from proflavine N,N,N’,N’-tetraacetic acid following the method in Ref. 10. Briefly, 1.0 g of proflavine (chroma) was suspended in 10.0 ml of water, and sodium chloracetate synthesized from 3.8 g of chloracetic acid and the equivalent moles of sodium hydroxide was added. Reflux the mixture for 4.0 hr and maintain its pH 8-10 with sodium hydroxide solution. And then cool and filter the reaction solution, acidify the filtered liquor with hydrochloric acid to pH 2.0. A brownish red precipitate is obtained, which was washed with water and purified repeatedly using the method of acid-base precipitation to get 0.5 g of blackish green solid PTA (m.p. 210.0-215.0”) with a yield of 12.0%. It is easily soluble in alkaline solution and hot water, slightly in acetone and alcohol and hardly in benzene and ether. IR: 1740 (c =0) cm-‘. Anal. Calcd. for Cz,H,,0,N3:C, 57.10; H, 9.51; N, 4.30. Found: C, 56.03; H, 9.38; N, 4.49 PTA was prepared as follows:
Optimization of conditions E$ect of the order of reagent added. The CL intensity is influenced by the added order of the reagents. It is found that acetone is indispensable and the CL intensity is the greatest by injecting hydrogen peroxide last. Efict of the concentration of sulfuric acid. In order to obtain a stable CL light emission, sulfuric acid is needed to adjust the acidity. The study of this influence is carried out with solutions containing 7.0 x 10m4 mol/l PTA, 2.0 pg/ml Ru(III), 0.93% HzOz, 20% acetone and variable amount of sulfuric acid in order to get 0.04 mol/l to 0.2 mol/l concentrations. The maximum intensity is obtained at a 0.12 mol/l sulfuric acid concentration. E#ect of the concentration of CL reagent PTA. The CL emission also depends on the CL reagent PTA concentration. The study of this influence is carried out in the range of 2.0 x low4 mol/l to 1.0 x 10m3 mol/l concentrations of PTA. The maximum intensity is obtained at a 7.0 x 10e4 mol/l PTA concentration. Eflect of the concentration of hydrogen peroxide. The light intensity rises with the increase of the concentration of hydrogen peroxide. The study of this influence is carried out in the range of 0.2 to 1.1% concentrations of hydrogen peroxide under the standard conditions showed above. The maximum intensity is obtained at a 0.93% H,O, concentration. Calibration and detection limit. It is found that the light intensity is directly proportional to Ru(II1) concentration between 2.0 x IO-* and 2.0 x 1O-5 g/ml. The linear correlation coefficient and detection limit are 0.9995 and 1.0 x 10eg g/ml, respectively. E&ct of foreign ions. The experimental results showed that a lOOO-foldK+, Na+, 500-fold Ca(II), Ba(II), Sr(II), Pb(II), Mg(II), Fe(III), Al(III), Cu(II), lOO-fold Zn(II), Sn(IV), Cd(II), Cr(III), Co(III), NO;, PO:-, Cl-, Br-, Se(VI), Nb(V), As(III), Hg(II), Bi(III), 40-fold Rh(III),
Determination of Ru by chemiluminescence
709
Table 1. Methods of CL determination of ruthenium System Luminol-H, 0, Luminol-KIO, Luminol-S,OiLuminol-H,O, Luminol-H,O, Luminol-H,O, Luminol-KIO, Luminol-KIO,-T&on-100 Lucigenin-H,O, PTA-acetone-H, SO,-H,O,
Action Cat. Cat. Cat. 2:: Cat. Cat. Cat. Cat. Cat.
Detection limit @g/ml) 5x 1x 1x 1x 1x 3x 1x 3.9 x 1x 1x
lo-’ lo-’ 10-r lo-’ IO-’ lo-’ IO-’ lo-’ lo-’ 10-r
Linear range @g/ml) (4-40) x 10-4 (1 - 10) x 1o-3 (1 - 10) x 10-r 0.003-0.1 0.001-0.1
Ref. 3 3 3 4 6 5 5 I 14
0.02-20
Table 2. Experimental results of 1 pg/ml ruthenium analysis in various mixtures (Recovery %) Components of sample 1:lO 1:20 1:30 1:30:10 1:10:30
Ru(III)-Os(IV) 98.5 97.0 96.0 -
Pd(II), Au(III), Pt(IV), OS(W), Ir(III), have no effect on the determination of 1.0 pg/ml of Ru(II1). Fe(I1) of 1.0 pg/ml can enhance the light emission intensity about 20%, which can be developed to determination of Fe(I1) and Fe(III), as Fe(II1) can be reduced to Fe(I1) by Na, SZ03. The interference of Cr(V1) can be eliminated by pre-reducing it to Cr(II1) with H,O, under acidic condition. Comparison with other methoris Methods for the determination of ruthenium based on luminol CL have been reported. But metal-catalyzed CL reactions are not selective because the CL reagent reacts with an oxidant such as hydrogen peroxide, producing the same luminescence spectrum in the presence of various metal ions. Interferences from the presence of other species, particularly metal ions, are due to the lack of selectivity, which is the major problem associated with these methods.‘2*‘3 Montano and Inglei4 studied the catalytic effect of Ru(II1) on the CL of the lucigenin-KOH-H, 0, system. The interference also can not be avoided. If the concentration of the analyte is much smaller than that the interfering species present in the sample, the best method is to achieve selectivity with specific reagent such as PTA prepared by us. In the present paper a new CL reagent for ruthenium determination is presented, based on the selectively catalytic effect of Ru(II1) on the PTA-acetone-H,SO,-H,O, CL system. A summary of the methods is given in Table 1.
Ru(III)-Au(III) 101.5 101.0 102.5 -
Determination samples
Ru(III)-Os(IV~Au(III) 101.0 101.5
of Ru(ZZZ) in the synthesized
Synthesized samples of various ratios of Au, OS and Ru were analyzed as described, not requiring the separation process as in Ref. 7. Satisfactory recoveries were obtained (Table 2).
REFERENCES 1. Li Zhenya and Zhao Minxheng, Kexue Tongbao, 1988, 33(9), 673. 2. Jiang ZhiMei and Meng Pangxi, Metallurgical Analysis, 1988, g(l), 26. 3. N. M. Lukovsakaya, A. V. Terletskaya and T. A. Bogoslovskaya, Zh. Anal. Khim., 1974, 29(11), 2268. 4. N. M. Lukovskaya, A. V. Terletskaya and N. F. Kusshchevskaya, Zh. Anal. Khim., 1978, 33(4), 750. 5. N. M. Lukovskaya and A. V. Terletskaya, Zh. Anal. aim., 1976, 31(4), 751. 6. A. T. Pilipenko, N. M. Lukovskaya, and A. V. Terletskaya et al., Zh. Anal. Khim., 1983, 38(6), 1071. 7. Xu Xiaowen, Li Lingying, Hu Chengwen and Wang Rong, Chemical Journal of Chinese Universities, 1990, 11(l), 87. 8. T. Ada&i, H. Takeishi and Y. Sasaki et al., Anal. Chim. Acta, 1989, 218(l), 77. 9. B. T. Eddy, A. M. E. Balaes and R. A. Hasty, Appl. Spectrosc., 1987, 41(8), 1442. 10. Ma Huimin, Research Report P.S., Wuhan University, 1992. 11. Liu Xilin, Kou Zongyan, Chen Xingguo and Hu Zide, Chinese Journal of Analytical Chemistry, 1992, 20(3), 345. 12. D. B. Paul, Talanta, 1978, B(7), 377. 13. T. Fujiwara and T. Kumamaru, Spectrochimica Acta Rev., 1990, 13(5), 399. 14. Larry A. Montano and J. D. Ingle, Jr., Anal. Chem., 1979, 51(7), 919.
Printed in Great Britain. All rights reserved 0039-9140/94s7.00 + 0.00
A NEW CHEMILUMINESCENCE REAGENT FOR THE DETERMINATION OF RUTHENIUM ZHIKE HE, QINGYAOLuo, HUIMIN MA, XIMAOYu and YUN’ E ZENG Department of Chemistry, Wuhan University, Hubei, 430072, China (Received 9 July 1993. Revised 7 October 1993. Accepted 7 October 1993). Summary-A new reagent proflavine-N, N, N’, N’-tetraacetic acid (PTA) synthesized in our laboratory has been found useful as a chemiluminescence reagent for the determination of ruthenium (Ru) in pH 2.5 sulfuric acid solution containing acetone, it can be oxidized catalytically by hydrogen peroxide. With Ru(II1) as catalyst, it emits light selectively. The linear range is between 2.0 x lo-* and 2.0 x 10e5 g/ml. The detection limit and the recovery rate of the method are 1.0 x low9 g/ml and 96.~102%, respectively. The method has been satisfactorily applied to determine trace Ru(II1) in synthesized sample.
Ru is one of the precious metals. A number of methods for the determination of Ru have been reported, principally involving spectrophotometric methods.1*2 In recent years, some chemiluminescence (CL) methods for its determination have also been presented.%’ CL has the advantages of greater sensitivity, wider linear dynamic range and simpler instrtmrentation requirements compared to other methods such as ICP-AES8v9 But these CL system involving luminol have poor selectivity. Some of them, which linear dynamic ranges are often only one order of magnitude.3*4 With the use of Triton X-100, the detection limit of the method in Ref. 7 decreased nearly one order of magnitude compared to that in Ref. 6. But the determination of Ru in Au-G-Ru mixtures required that the Ru first be separated by reversed phase paper chromatograph with di-p-methyl phenyl sulfoxide as the stationary phase. Because the precious metals are rare in nature, the highly sensitive CL method is required to meet the needs of scientific research. Therefore the development of a new, highly sensitive and selective CL reagent is significant. Having tested a series of new fluorescent reagents, ‘Owe discovered that the determination of trace amount of Ru(II1) with proflavineJV,N,N’,N’-tetraacetic acid as a CL reagent is highly selective and without blank. This method can be directly applied to the determination of Ru(II1) in Au-O-Ru mixtures with satisfactory results.
EXPERIMENTAL Apparatus
CL meter, Model FG83-1 (Fuzhou radio No. 6 factory China), including photomultiplier tube and fused-silica reaction cell, and a type 3066 recorder (Sichuan instrumental general factory, China) were used. Reagents
A 0.5 mg/ml Ru(II1) stock-solution was prepared by weighing and dissolving 0.1644 g of [(NH,),Ru(H,O)Cl,] in warm hydrochloric acid of 2 mol/l,” and then diluting to 100 ml with water. Standard solution were obtained by diluting the stock solution with water. A 3.5 x 10e3 mol/l stock solution of PTA was prepared by weighing and dissolving 0.1545 g of PTA in some 2 mol/l sodium hydroxide and diluting to 100 ml with water. Hydrogen peroxide solution, 4.8%. Further diluted as required. All solutions were prepared from analytical grade chemicals and redistilled water. Procedure
A 1.0 ml portion of 3.5 x 10e3 mol/l PTA, 1.O ml of 0.6 mol/l sulfuric acid, 1.0 ml of 3.0 x 10m6 g/ml Ru(II1) and 1.0 ml of acetone were mixed in order in the reaction cell and then set in the black box. After 30 set, inject 1.0 ml of 4.8% hydrogen peroxide 707
HE ZHIKKet al.
708
RESULTS AND DISCUSSION
2
1
0 t NW
Fig. 1. Kinetic curve of PTA CL light emission; 3.0 pg/mI Ru(III), pH 2.5.
solution and record the signal at the same time (see Fig. 1). Synthesis of CL reagent PTA. PTA was synthesized from proflavine N,N,N’,N’-tetraacetic acid following the method in Ref. 10. Briefly, 1.0 g of proflavine (chroma) was suspended in 10.0 ml of water, and sodium chloracetate synthesized from 3.8 g of chloracetic acid and the equivalent moles of sodium hydroxide was added. Reflux the mixture for 4.0 hr and maintain its pH 8-10 with sodium hydroxide solution. And then cool and filter the reaction solution, acidify the filtered liquor with hydrochloric acid to pH 2.0. A brownish red precipitate is obtained, which was washed with water and purified repeatedly using the method of acid-base precipitation to get 0.5 g of blackish green solid PTA (m.p. 210.0-215.0”) with a yield of 12.0%. It is easily soluble in alkaline solution and hot water, slightly in acetone and alcohol and hardly in benzene and ether. IR: 1740 (c =0) cm-‘. Anal. Calcd. for Cz,H,,0,N3:C, 57.10; H, 9.51; N, 4.30. Found: C, 56.03; H, 9.38; N, 4.49 PTA was prepared as follows:
Optimization of conditions E$ect of the order of reagent added. The CL intensity is influenced by the added order of the reagents. It is found that acetone is indispensable and the CL intensity is the greatest by injecting hydrogen peroxide last. Efict of the concentration of sulfuric acid. In order to obtain a stable CL light emission, sulfuric acid is needed to adjust the acidity. The study of this influence is carried out with solutions containing 7.0 x 10m4 mol/l PTA, 2.0 pg/ml Ru(III), 0.93% HzOz, 20% acetone and variable amount of sulfuric acid in order to get 0.04 mol/l to 0.2 mol/l concentrations. The maximum intensity is obtained at a 0.12 mol/l sulfuric acid concentration. E#ect of the concentration of CL reagent PTA. The CL emission also depends on the CL reagent PTA concentration. The study of this influence is carried out in the range of 2.0 x low4 mol/l to 1.0 x 10m3 mol/l concentrations of PTA. The maximum intensity is obtained at a 7.0 x 10e4 mol/l PTA concentration. Eflect of the concentration of hydrogen peroxide. The light intensity rises with the increase of the concentration of hydrogen peroxide. The study of this influence is carried out in the range of 0.2 to 1.1% concentrations of hydrogen peroxide under the standard conditions showed above. The maximum intensity is obtained at a 0.93% H,O, concentration. Calibration and detection limit. It is found that the light intensity is directly proportional to Ru(II1) concentration between 2.0 x IO-* and 2.0 x 1O-5 g/ml. The linear correlation coefficient and detection limit are 0.9995 and 1.0 x 10eg g/ml, respectively. E&ct of foreign ions. The experimental results showed that a lOOO-foldK+, Na+, 500-fold Ca(II), Ba(II), Sr(II), Pb(II), Mg(II), Fe(III), Al(III), Cu(II), lOO-fold Zn(II), Sn(IV), Cd(II), Cr(III), Co(III), NO;, PO:-, Cl-, Br-, Se(VI), Nb(V), As(III), Hg(II), Bi(III), 40-fold Rh(III),
Determination of Ru by chemiluminescence
709
Table 1. Methods of CL determination of ruthenium System Luminol-H, 0, Luminol-KIO, Luminol-S,OiLuminol-H,O, Luminol-H,O, Luminol-H,O, Luminol-KIO, Luminol-KIO,-T&on-100 Lucigenin-H,O, PTA-acetone-H, SO,-H,O,
Action Cat. Cat. Cat. 2:: Cat. Cat. Cat. Cat. Cat.
Detection limit @g/ml) 5x 1x 1x 1x 1x 3x 1x 3.9 x 1x 1x
lo-’ lo-’ 10-r lo-’ IO-’ lo-’ IO-’ lo-’ lo-’ 10-r
Linear range @g/ml) (4-40) x 10-4 (1 - 10) x 1o-3 (1 - 10) x 10-r 0.003-0.1 0.001-0.1
Ref. 3 3 3 4 6 5 5 I 14
0.02-20
Table 2. Experimental results of 1 pg/ml ruthenium analysis in various mixtures (Recovery %) Components of sample 1:lO 1:20 1:30 1:30:10 1:10:30
Ru(III)-Os(IV) 98.5 97.0 96.0 -
Pd(II), Au(III), Pt(IV), OS(W), Ir(III), have no effect on the determination of 1.0 pg/ml of Ru(II1). Fe(I1) of 1.0 pg/ml can enhance the light emission intensity about 20%, which can be developed to determination of Fe(I1) and Fe(III), as Fe(II1) can be reduced to Fe(I1) by Na, SZ03. The interference of Cr(V1) can be eliminated by pre-reducing it to Cr(II1) with H,O, under acidic condition. Comparison with other methoris Methods for the determination of ruthenium based on luminol CL have been reported. But metal-catalyzed CL reactions are not selective because the CL reagent reacts with an oxidant such as hydrogen peroxide, producing the same luminescence spectrum in the presence of various metal ions. Interferences from the presence of other species, particularly metal ions, are due to the lack of selectivity, which is the major problem associated with these methods.‘2*‘3 Montano and Inglei4 studied the catalytic effect of Ru(II1) on the CL of the lucigenin-KOH-H, 0, system. The interference also can not be avoided. If the concentration of the analyte is much smaller than that the interfering species present in the sample, the best method is to achieve selectivity with specific reagent such as PTA prepared by us. In the present paper a new CL reagent for ruthenium determination is presented, based on the selectively catalytic effect of Ru(II1) on the PTA-acetone-H,SO,-H,O, CL system. A summary of the methods is given in Table 1.
Ru(III)-Au(III) 101.5 101.0 102.5 -
Determination samples
Ru(III)-Os(IV~Au(III) 101.0 101.5
of Ru(ZZZ) in the synthesized
Synthesized samples of various ratios of Au, OS and Ru were analyzed as described, not requiring the separation process as in Ref. 7. Satisfactory recoveries were obtained (Table 2).
REFERENCES 1. Li Zhenya and Zhao Minxheng, Kexue Tongbao, 1988, 33(9), 673. 2. Jiang ZhiMei and Meng Pangxi, Metallurgical Analysis, 1988, g(l), 26. 3. N. M. Lukovsakaya, A. V. Terletskaya and T. A. Bogoslovskaya, Zh. Anal. Khim., 1974, 29(11), 2268. 4. N. M. Lukovskaya, A. V. Terletskaya and N. F. Kusshchevskaya, Zh. Anal. Khim., 1978, 33(4), 750. 5. N. M. Lukovskaya and A. V. Terletskaya, Zh. Anal. aim., 1976, 31(4), 751. 6. A. T. Pilipenko, N. M. Lukovskaya, and A. V. Terletskaya et al., Zh. Anal. Khim., 1983, 38(6), 1071. 7. Xu Xiaowen, Li Lingying, Hu Chengwen and Wang Rong, Chemical Journal of Chinese Universities, 1990, 11(l), 87. 8. T. Ada&i, H. Takeishi and Y. Sasaki et al., Anal. Chim. Acta, 1989, 218(l), 77. 9. B. T. Eddy, A. M. E. Balaes and R. A. Hasty, Appl. Spectrosc., 1987, 41(8), 1442. 10. Ma Huimin, Research Report P.S., Wuhan University, 1992. 11. Liu Xilin, Kou Zongyan, Chen Xingguo and Hu Zide, Chinese Journal of Analytical Chemistry, 1992, 20(3), 345. 12. D. B. Paul, Talanta, 1978, B(7), 377. 13. T. Fujiwara and T. Kumamaru, Spectrochimica Acta Rev., 1990, 13(5), 399. 14. Larry A. Montano and J. D. Ingle, Jr., Anal. Chem., 1979, 51(7), 919.