Determination of methylmercury by the species-specific isotope addition method using a newly developed HPLC-ICP MS coupling technique with ultrasonic nebulization

A novel technique has been developed for the determination of trace amounts of melthylmercury in various sample matrices. The newly developed HPLC method makes it possible to separate methylmercury and inorganic mercury with ultrasonic nebulization and detection by ICP MS for different mercury isotopic masses. The isotope-specific detection allows the application of the species-specific isotope addition method for the determination of methylmercury with a correction for artifact formation, The well-known water-vapour distillation method was used in combination with an enriched stable inorganic mercury isotope (Hg-200(2+)) for the separation of methylmercury from various matrices. The subsequent determination of CH3-Hg-200(+) generated from Hg-200(2+) was used in the correction for artifact formation during sample preparation. In comparison with a previously developed HPLC coupling technique with HPF-HHPN (high-performance flow/ hydraulic high-pressure nebulization), the stability of the detection procedure was improved considerably. The limit of detection (S/N = 3) for methylmercury was calculated to be about 0.015 mu g kg(-1). (C) 1998 John Wiley & Sons, Ltd.