Determination of dissolved inorganic antimony(V) and antimony(III) species in natural waters by hydride generation atomic absorption spectrometry

Abstract

A method is described for the determination of dissolved antimony(III) and antimony(V) species in natural waters. The technique is based on the rapid evolution of stibine from the sample solution by reduction with sodium tetrahydroborate(III), cryogenic pre-concentration and atomisation in an electrically heated quartz tube furnace mounted in the light path of an atomic absorption spectrometer. Differentiation of antimony(III) and -(V) species is achieved by exploiting the pH dependence of the tetrahydroborate(III) reduction step. The procedure is applicable over a working range of 0–300 ng l^–1 of antimony and permits a sample throughput of ca. 7 analyses per hour. Detection limits are ca. 10 ng l^–1 for total antimony and ca. 1 ng l^–1 for antimony(III). Potentially interfering species have been investigated but, at levels expected in natural waters, did not influence the analytical results obtained using the method.