For microwave digestion,about 0.05 g of homogenized and dried samples of fish was accurately weighed directly into the PTFE-TFM digestion vessels.To each sample,5.0 ml of concentrated nitric acid, 2.0 ml of hydrogen peroxide and 1.0 ml water were added. The analytical reagent blanks were also prepared and these contained only the acids. The vessels were sealed and placed into the Roter 8 for the microwave digestion. After the digestion process, the digestate liquids were transferred to the 50 ml autosampler polypropylene vials and laboratory ASTM Type 1 water was added to a final total volume of 20 ml