Mercury determination in environmental samples using EDXRF and CV-AAS

摘要

The determination of total Hg in various environmental matrices was investigated using energy-dispersive x-ray fluorescence (EDXRF) spectrometry on both powdered and digested samples and cold vapor atomic absorption spectrometry (CV-AAS) on digested samples. Several microwave decomposition procedures were evaluated. The use of different acid mixtures, microwave power settings and decomposition times were compared, in addition to the analysis of wet and freeze dried samples. A set of standard reference samples were used to evaluate the procedures. An H2SO4-HNO3-H2O2 mixture was found to be optimal for the complete mineralization and digestion of biological samples for Hg by CV-AAS, whereas for EDXRF both HNO3-H2O2 and H2SO4-HNO3-H2O2 mixtures gave good results. The detection limit of EDXRF could be significantly decreased (from 0.2 mu g g(-1) to 0.058 mu g g(-1)) by performing the analysis on digested samples. Good agreement was obtained between the EDXRF and CV-AAS analysis. The results were also in good agreement with certified values. The methods were applied to environmental samples (coal, vegetation, fish and sediment) and human hair in a coal mining area and in locations where coal is used for cooking in Vietnam. (C) 1998 John Wiley & Sons, Ltd. [References: 29]