Development of a liquid chromatography-inductively coupled plasma mass spectrometry method for the simultaneous determination of methylmercury and inorganic mercury in human blood.

We developed and validated a liquid chromatography-inductively coupled plasma mass spectrometry (LC-ICP-MS) method for simultaneous determination of methylmercury (MeHg) and inorganic mercury (I-Hg) in human blood samples. Thallium was used as an internal standard for determination of MeHg and 196Hg was used as an internal standard for I-Hg determination. The blood samples were extracted using a 7% (v/v) HCl solution containing 1.5% (w/v) l-cysteine. A 10% (w/v) trichloroacetic acid solution was used to precipitate proteins in the extract. Mercury species were measured by LC-ICP-MS. The linear range of the assay was 0.08-60  ng/mL for MeHg and 0.05-2.5 ng/mL for I-Hg. The method was validated with the Certified Reference Materials Blood Mercury (Institut National de Santé Publique Québec, Quebec, Canada) and Seronorm™ Trace Elements Whole Blood (Sero AS, Billingstad, Norway). Additional validation was performed by comparing the results obtained with those from a widely used gas chromatography method with electron-capture detection. The proposed method was applied to the simultaneous determination of MeHg and I-Hg in human blood samples. The LC-ICP-MS method provides precise, accurate, and robust determination of MeHg and I-Hg levels in human blood over a long period and has a simple and quick sample preparation. We expect that this method will contribute to large-scale evaluation of human exposure to mercury compounds in future.