Rapid speciation analysis of mercury in seawater and marine fish by cation exchange chromatography hyphenated with inductively coupled plasma mass spectrometry

•Hg2+, MeHg, EtHg and PhHg were separated on two sequential 12.5-mm SCX columns.•The shortest separation time (2–2.5 min) was consumed.•The mobile phase was most environment-friendly and fairly compatible with ICP-MS.

In this work, a hybrid method for the rapid speciation of mercury compounds by cation exchange chromatographic separation and inductively coupled plasma mass spectrometry (ICP-MS) detection is reported. Effective separation of inorganic mercury (Hg2+), methylmercury (MeHg), ethylmercury (EtHg) and phenylmercury (PhHg) within 2–2.5 min was achieved on two consecutive 12.5-mm strong cation exchange guard columns with 2.0 mM l-cysteine or thiourea (pH 2.0) as the mobile phase. This separation met the requirements of green analytical chemistry such as the prevention of toxic waste, safer HPLC mobile phases, and short separation times to reduce operating costs. The detection limits for Hg2+, MeHg, EtHg and PhHg were 0.019, 0.027, 0.031 and 0.022 μg L−1, each, and the repeatabilities of peak height and peak area (5.0 μg L−1 for each Hg species) were all lower than 3%. Contents of Hg species and total mercury in certified reference materials of seawater (GBW(E) 080042) and fish tissue (GBW 10029) were in good accordance with the certified values, and satisfactory recoveries (96–102% for GBW(E) 080042 and 94–101% for GBW 10029) validated the developed method. The developed method was applied for the speciation of mercury in five seawater sample and five marine fish samples. The concentrations of mercury species in all analyzed fish samples did not exceed the permissible levels of the National Standard of China.