Open focused microwave-assisted sample preparation for rapid total and mercury species determination in environmental solid samples

This paper describes rapid, simple microwave-assisted leaching/digestion procedures for total and mercury species determination in sediment samples and biomaterials. An open focused microwave system allowed the sample preparation lime to be dramatically reduced to only 2-4 min when a power of 40-80 W was applied. Quantitative leaching of methylmercury from sediments by HNO3 solution and complete dissolution of biomaterials by an alkaline solution, such as 25% TMAH solution, were obtained. Methyl-mercury com;hounds were kept intact without decomposition or losses by ei;evaporation. Quantitative recoveries of total mercury were achieved with a two-step microwave attack using a combination of HNO3 and H2O2 solutions as extractant. The whole pretreatment procedure only takes 15 min, which can be further shortened by an automated robust operation with an open focused system. These analytical procedures were validated by the analysis of environmental certified reference materials. The results confirm that the open focused microwave technique is a promising tool for solid sample preparation in analytical and environmental chemistry.