Effect of metal sensitizers on photochemical vapor generation of bismuth for analytical atomic spectrometry

Abstract

Conditions of photochemical vapor generation of bismuth were optimized in a flow-injection system with a standard mercury low-pressure tube lamp and a coiled reactor. A high-resolution continuum source atomic absorption spectrometer was used as a detector that was equipped with a miniature diffusion flame as an atomizer. The influence of flow rate of a carrier gas, irradiation time and composition of a reaction medium was investigated. Combination of 40% (v/v) acetic acid with 1.25% (v/v) formic acid was found optimal. Subsequently, the use of various metals as sensitizers was studied to achieve maximum generation efficiency. Except the already published positive effect of Fe2+, three new sensitizers were found, with the enhancement effect in the following order: Cu2+ < Cd2+ << Co2+. Interference from nitric acid which is commonly used for digestion of real samples was investigated. The limit of detection achieved with the optimal conditions was 5.9 mu g L-1.