Separation and determination of tellurium(IV) and -(VI) by electrothermal atomic absorption spectrometry using a tungsten furnace after collection as the 3-phenyl-5-mercapto-1,3,4-thiadiazole -2(3H)-thione-tellurium complex on cobalt(III) oxide

Abstract

Using cobalt(III) oxide powder as a collector of tellurium(IV) and -(VI), the latter are separated from matrix components contained in a sample solution, then determined by electrothermal atomic absorption spectrometry using a tungsten furnace. When only cobalt(III) oxide powder was used for the collection of tellurium, the recovery of tellurium(IV) and -(VI) increased as the sample solution became more basic; almost 100% recovery was obtained at pH 11.0. When 0.1% m/v 3-phenyl-5-mercapto-1,3,4-thiadiazole-2(3H)-thione potassium salt (bismuthiol II) was used as an auxiliary agent for the collection, there was difference in the collection behavior between tellurium(IV) and -(VI) depending on the pH of sample solution (100 ml): 100% recovery was obtained at pH 1-7 for tellurium(IV) and at pH 3-7 for tellurium(VI). Therefore, by collecting tellurium(IV,VI) at pH 4.0 and then tellurium(IV) at pH 1.0, fractionation and determination of tellurium(IV,VI) can be achieved. The cobalt(III) oxide powder used as a collector is also effective as a chemical modifier in the determination; by introducing cobalt(III) oxide powder in the form of a slurry (5 ml) into a furnace, the volatilization loss of tellurium could be suppressed up to a charring temperature of 1400 °C. For 1.25 µg per 5 ml (0.25 mg l^–1) tellurium(IV), when this method was used the relative standard deviation (n=6) was <3%. The detection limit (3σ) was 12 µg l^–1 (0.12 ng per 10 µl). The method applied to several water samples, experiments being performed on the fractionation and determination of tellurium(IV,VI), and 100% recovery was obtained.

References

1. Y. Hashimoto and Y. Sekine, Bunseki, 1990, 2, 111.
2. T. Ashino, K. Takada and K. Hirokawa, Anal. Chim. Acta, 1994, 297, 443.
3. S. Hikime, Bull. Chem. Soc. Jpn., 1960, 33, 761.
4. H. Yoshida, M. Taga and S. Hikeme, Talanta, 1966, 13, 185.
5. K. L. Cheng, Talanta, 1961, 8, 301.
6. J. C. Van Loon and R. R. Barefoot, Analyst, 1992, 117, 563.
7. M. O. Andreae, Anal. Chem., 1984, 56, 2064.
8. G. Schlemmer and B. Welz, Spectrochimica Acta, Part B, 1986, 41, 1157.
9. K. Dittrich, T. Franz and R. Wennrich, Spectrochimica Acta, Part B, 1995, 50, 1655.
10. G. Weibust and F. J. Lanmyhr, Anal. Chim. Acta, 1981, 128, 23.
11. M. Suzuki and K. Ohta, Prog. Anal. At. Spectrosc., 1983, 6, 49.
12. M. Suguki, K. Ohta, T. Yamakita and T. Katsuno, Spectrochimica Acta, Part B, 1981, 36, 679.
13. H. Tao, Bunseki Kagaku, 1997, 46, 239.
14. K. Yokoi, Bunseki, 1996, 2, 108.
15. K. Hiraki and Y. Nakaguchi, Bunseki, 1994, 12, 1020.
16. N. P. Vela and J. A. Caruso, J. Anal. At. Spectrom., 1993, 8, 787.
17. T. Narukawa, A. Uzawa, W. Yoshimura and T. Okutani, J. Anal. At. Spectrom., 1997, 12, 781.
18. T. Narukawa, A. Uzawa, W. Yoshirura and T. Okutani, Anal. Sci., 1998, 14, 779.
19. T. Narukawa, W. Yoshimura and A. Uzawa, Bull. Chem. Soc. Jpn., 1998, 71, 1385.
20. T. Narukawa, W. Yoshimura and A. Uzawa, Bunseki Kagaku, 1998, 47, 707.