Behavior of thorium, zirconium, and vanadium as chemical modifiers in the determination of arsenic by electrothermal atomization atomic absorption spectrometry

The comparative effect of thorium, zirconium and vanadium used as chemical modifiers in wall and platform atomization of arsenic using two sample introduction modes (aerosol vs. liquid drop) was studied. The effect of proton concentration (as hydrochloric acid and nitric acid) on the behavior of these modifiers was also tested. A beneficial effect on the stabilization of arsenic from all the chemical modifiers was essentially derived in the presence of nitric acid mainly for the aerosol introduction mode. Nonetheless, the highest sensitivity and the best stabilization of arsenic were obtained using zirconium and thorium as a chemical modifier, because pyrolysis temperatures as high as ∼1500°C can be used. The mechanistic action of the chemical modifiers used is also studied, resulting in the formation of a mixture of oxides stabilized at high temperatures.