Vapour-phase acid digestion of inorganic and organic matrices for trace element analysis using a microwave heated bomb

Abstract

A vapour-phase microwave pressure digestion technique employing a special polytetrafluoroethylene-based microsampling device was evaluated for the acid digestion of marine sediment and biological tissue samples prior to the determination of their trace and minor element content. Inorganic and organic constituents are almost completely solubilized by vapour-phase attack (with an HNO₃–HF mixture for the marine sediment and HNO₃ for the marine biological tissue) in a perfluoroalkoxy-Teflon pressure bomb. The residue was taken up in 0.5 mol dm^–3 HNO₃ and analysed by flame and electrothermal atomic absorption spectrometry. Good agreement between the results and certified values for 15 elements was found. The sample preparation time was approximately 45 min for the biological tissue and 90 min for the sediment (including the subsequent cooling time and preparation of the final solution).