Investigation of some fundamental conditions for the determination of arsenic, lead and tellurium with continuous hydride generation-atomic absorption spectrometry

Abstract

A system is described which permits the atomic absorption spectrometric determination of arsenic, lead and tellurium after formation of their volatile hydrides. The apparatus consists of an electrically heated quartz cell atomizer which has several advantages in terms of sensitivity and noise characteristics and of a newly-developed, automated hydride generation system which enables the gaseous hydrides produced by sodium borohydride to be introduced directly into the cell. To achieve the optimum performance for these elements, some fundamental parameters affecting their production and introduction have been investigated. From the results on relative stability of arsenic, lead and tellurium hydrides, for the former one, both direct transfer and collection modes can be used, whereas for the latter two the use of such a direct transfer mode as used in the present hydride generation system is undoubtedly preferred. The sensitivities for these elements appear to be strongly dependent on relative stability of their hydrides. Furthermore, a low sensitivity for tellurium could be due to a notable loss of the hydride by its reaction or dissolution with water as well as to the instability of tellurium hydride. Under the optimum conditions, the detection limits (S/N=2) are 0.5 ng/ml, 1 ng/ml and 1 ng/ml for arsenic, lead and tellurium, respectively and the reproducibilities (RSD's) of the present method based on ten determinations of As 0.05µg/ml, Pb 0.1µg/ml and Te 0.1µg/ml range from 0.5% to 1.0%. Analytical calibration graphs obtained under the optimum conditions have linear dynamic ranges up to As 0.1µg/ml, Pb 0.5µg/ml and Te 0.5µg/ml. Additionally, the reagent blanks in the present system are of little or no significance. © 1981, The Japan Society for Analytical Chemistry. All rights reserved.