Reversed-phase high-performance liquid chromatographic separation of inorganic mercury and methylmercury driven by their different coordination chemistry towards thiols

Since mercuric mercury (Hg2+) and methylmercury (CH3Hg+) display different toxicological properties in mammals, methods for their quantification in dietary items must be available. Employing Hg-specific detection, we have developed a rapid, isocratic, and affordable RP-HPLC separation of these mercurials using thiol-containing mobile phases. Optimal separation was achieved with a 50 mM phosphate-buffer containing 10 mM l-cysteine at pH 7.5. The separation is driven by the on-column formation of complexes between each mercurial and l-cysteine, which are then separated according to their different hydrophobicities. The developed method is compatible with inductively coupled plasma atomic emission spectrometry and was applied to analyze spiked human urine.