Chemical vapor generation for sample introduction into inductively coupled plasma atomic emission spectroscopy: vaporization of antimony(III) with bromide

A new method for antimony determination in soils is proposed. It is based on the chemical vapor generation of Sb(III) with bromide, after a reaction in sulfuric acid media and transport of the gaseous phase into an inductively coupled plasma for atomic emission spectrometry. The experimental variables influencing the method were delimited by experimental design and the most important were finally optimized by the modified Simplex method. In optimized conditions the method involves the reaction of 579 mul concentrated sulfuric acid with 120 mul 5% w/v KBr and 250 mul antimony solution. Measurement of antimony emission intensity at 217.581 nm provides a method with an absolute detection limit of 3.5 ng and a precision (RSD) of 5.8% for the injection of five replicates of 175 ng Sb(III) (250 mul of 0.7 mug ml(-1) solution). The interference of common anions and cations on the antimony signal was evaluated. A 21% Sb(III) volatilization efficiency was calculated from the mean of six experiments at optimum conditions. The accuracy of the methodology was checked by the analysis of one standard reference soil after acid decomposition heating in a microwave oven.