Microwave treatment of biological samples for methylmercury determination by high performance liquid chromatography-cold vapour atomic fluorescence spectrometry

A simple and rapid microwave-assisted alkaline digestion procedure was deve loped in combination with high performance liquid chromatography-ultraviole t post-column oxidation-cold vapour atomic fluorescence spectrometric detec tion for methylmercury determination in biological tissues. Since the stabi lity of methylmercury in methanolic potassium hydroxide solution under micr owave irradiation was verified, the microwave-assisted extraction procedure was optimized in terms of quantitative recovery of methylmercury and minim um time required. The alkaline extracts were subjected to clean-up steps wi th dichloromethane and hydrochloric acid in order to reduce matrix interfer ences in methylmercury determination. The effects of matrix interferences w ere checked by comparison of the slopes corresponding to calibration and st andard addition curves. The accuracy of the method was evaluated by the ana lysis of two biological certified reference materials, NRC TORT-2 and BCR 4 63. The results obtained by the proposed method were in good agreement with the certified values of methylmercury concentration in both materials. The detection limit was 10 mug kg(-1) and the relative standard deviation was < 8% for methylmercury concentrations ranging from 0.15 to 3.0 mg kg(-1).