Mechanisms of atomisation of tin in organic matrices in graphite furnace atomic absorption spectrometry

Abstract

Organic solvents such as hexane give double peak signals for tin when it is atomised at lower ashing temperatures from the surface of a graphite atomiser. As the hold time for the ashing step increases, the first signal decreases, leaving the total area absorbances and the appearance temperature nearly constant. This shows a conversion of one species for the first peak into another for the second. The double peaks were analysed by using Arrhenius plots and two atomising species, Sn (s or l) and SnO₂(s or l), were ascribed to the species in the rate-determining step for the first and second signals, respectively. It was concluded that the organic solvents provide active carbon, available for reduction of tin, to lead to the appearance of the first peak. Adding oxygen to the argon sheath gas decreases the first peak and greatly enhances the absorbances.