Comparative study to evaluate the effect of different acids on the determination of germanium by hydride generation–inductively coupled plasma atomic emission spectrometry

Abstract

A comparative study was performed to evaluate the effect of hydrochloric, tartaric, citric, oxalic, acetic and sulfosalicilic acids on the hydride generation of germanium at trace levels in a continuous flow system and inductively coupled plasma atomic emission spectrometry (ICP–AES) detection. The operating conditions (chemical and physical parameters) and the concentrations of the acids studied have been optimized for the generation of GeH 4 (germane). Analytical figures of merit including detection limits, precisions and linear dynamic ranges are given for the six acids employed. The detection limits for Ge ranged between 0.096 and 0.295 μg l −1 depending on the acid used to generate germane. Compared to a conventional continuous nebulization, the present coupling gives a sensitivity increase of a factor of approximately two orders of magnitude. The interferent effect of transition metals (Cd, Co, Cu, Cr, Mn, Ni, Zn), other hydride forming elements (As, Bi, Pb, Sb, Se, Sn, Te) and Hg upon Ge signal using the different acids studied were evaluated. Tartaric acid is the most suitable reaction medium, in terms of efficiency in the hydride generation process and in reduction of interferences. Besides, it allows for less strict control of the pH at which the generation of germane takes place. The proposed method was applied to the determination of Ge in coal fly ashes.