Studies in hydride generation atomic fluorescence determination of selenium and tellurium. Part 1 — self interference effect in hydrogen telluride generation and the effect of KI

Abstract

The effects of tetrahydroborate (0.02–1%) and iodide (0–3 M) were investigated in determination of tellurium and selenium by hydride generation atomic fluorescence spectrometry. The effect of tetrahydroborate and iodide concentration were tested on the shape of calibration curves in concentration range of 1–1000 ng ml −1 analyte. Reductant deficiency resulted in a moderate sensitivity depression for tellurium but dramatically reduced the useful dynamic range down to 50 ng ml −1. On the contrary, selenium calibration curves retained a linear character even under conditions generating strong sensitivity depression. Curvature and rollover of tellurium calibration curves has been addressed to a self-interference effect caused by the formation of finely dispersed elemental tellurium. Iodide ions were found to have beneficial or no negative effects in the hydrogen telluride generation. Addition of iodide on-line to the sample has been proved effective in the control of the self-interference effect and allows to work in mild reaction conditions. Moreover, it allows a good control of Cu(II) interference and eliminates Ni(II) and Co(II) interferences. The method has been successfully applied to determination of tellurium in copper and lead ores certified reference materials.