Ultra-trace determination of methylmercuy in seafood by atomic fluorescence spectrometry coupled with electrochemical cold vapor generation

Highlights: • Methylmercury detection by ECVG-AFS without pre-separation by HPLC is proposed. • Methylmercury is atomized by direct electrochemical reduction with no reductant. • Remarkably better sensitivity is obtained than the traditional HPLC-UV-AFS method. • Glassy carbon is the best cathode material to generate Hg vapor from methylmercury. - Abstract: A homemade electrochemical flow cell was adopted for the determination of methylmercury. The cold vapor of mercury atoms was generated from the surface of glassycarbon cathode through the method of electrolytic reduction and detected by atomic fluorescence spectroscopy subsequently. The operating conditions were optimized with 2 ng mL⁻¹ methylmercury standard solution. The caliberation curve was favorably linear when the concentrations of standard HgCH₃⁺ solutions were in the range of 0.2–5 ng mL⁻¹(as Hg). Under the optimized conditions, the limit of detection (LOD) for methylmercury was 1.88 × 10⁻³ ng mL⁻¹ and the precision evaluated by relative standard deviation was 2.0% for six times 2 ng mL⁻¹ standard solution replicates. The terminal analytical results of seafood samples, available from local market, showed that the methylmercury content ranged within 3.7–45.8 ng g⁻¹. The recoveries for methylmercury spiked samples were found to be in the range of 87.6–103.6% and the relative standard deviations below 5% (n = 6)were acquired, which showed this method was feasible for real sample analysis.