Rapid determination of methylmercury in biological materials by GC-MIP-AESor GC-ICP-MS following simultaneous ultrasonic-assisted in situ ethylationand solvent extraction

A simple and rapid sample pre-treatment procedure was developed for the det ermination of methylmercury in biological materials. The procedure is based on acid leaching (5 min) of sample materials followed by simultaneous in s itu derivatisation and extraction (40 min) in the presence of sodium tetrae thylborate and nonane, buffered at pH 7.0, in an ultrasonic held. The nonan e phase with an overall average recovery of methylmercury higher than 90% w as analysed by gas chromatography (GC) coupled to microwave induced plasma atomic emission spectrometry (MIP-AES) or inductively coupled plasma mass s pectrometry (ICP-MS). Detection limits (as Hg), based on three times the st andard deviation of a standard solution, were 4.4 ng g(-1) for GC-MIP-AES a nd 2.6 ng g(-1) for GC-ICP-MS. No artefact formation of methylmercury durin g sample pretreatment was observed following the addition of a (201)Hg2(+) isotope standard. The method was validated by the analysis of three biologi cal certified reference materials and applied to the determination of methy lmercury in a fish sample.