Abstract

Methylmercury and total mercury in sea food were analysed by flow injection cold vapour atomic absorption spectrometry using sodium tetrahydroborate as a reductant. Methylmercury in aquatic species was leached with HBr 47% as neutral MeHgBr complex and quantitatively extracted into toluene. MeHgBr in toluene was back extracted with L-cysteine into aqueous phase in form of negatively charged MeHg-L-cysteine complex. All organic compounds in the aqueous phase were decomposed with KMnO4/H2SO4 to convert methyl mercury to Hg2+ for direct cold vapour reaction. The seafood sample was digested with aquaregia for total mercury analysis. The limits of detection/quantitation for methylmercury and total mercury were là 0.69/1.3 ng/g and 0.70/2.2 ng/g (as Hg), respectively. The recovery of the analytical methods for MeHg and total Hg were 96.5–105% and 93–101% within the concentration ranges of 2–700 ng/g Hg. The concentrations of MeHg and total Hg in some common seafood such as fish, shrimp and squid were in ranges of 1.2–483.5 ng/g and 4.0 ÷ 663.4 ng/g.