Acid extraction for the determination of methyl mercury in biotissues by isotope dilution gas chromatography inductively coupled plasma-mass spectrometry

Methyl mercury (MeHg) is a common contaminant worldwide. Health authorities keep monitoring MeHg levels in biological and environmental samples to assess the corresponding exposure in the population. So far, a basic leaching has been mostly used for the MeHg extraction. In this study, it was demonstrated that methanesulfonic acid, commonly used for amino acid extraction, can be used for MeHg extraction. Species-specific isotope dilution was employed to achieve accurate results. The method was validated by analysis of dogfish liver certified reference material (DOLT-4). The derivatized extracts were then analyzed with gas chromatography-inductively coupled plasma-mass spectrometry (GC-ICP-MS). Results obtained for MeHg in DOLT-4 are in agreement with the certified value (t-test, P = 0.05), confirming that methanesulfonic acid extraction is suitable for extraction of MeHg in biological tissues. This new procedure could be of particular interest in biological and toxicological studies where a simultaneous determination of MeHg and certain amino acids is sometimes required.