Determination of Methylmercury and Ethylmercury in Aquatic Products by Gas Chromatography-Mass Spectrometry with Stable Isotope-Labelled Internal Standard

作者：Zhang Xiu Yao; Cai Xin Xin^*; Zhang Xiao Yi

来源：Chinese Journal of Analytical Chemistry, 2014, 42(10): 1524-1529.

• Gas chromatography-mass spectrometry
• Methylmercury
• Ethylmercury
• Stable isotope dilution method
• Aquatic products

A method for the determination of methylmercury (MeHg) and ethylmercury (EtHg) in aquatic products was developed using gas chromatography-mass spectrometry with stable isotope-labelled internal standard. After ultrasonication assisted hydrochloric acid extraction, MeHg and EtHg in samples were extracted into toluene under the presence of sodium chloride and then back-extracted into cysteine aqueous solution. The MeHg and EtHg were released from their complexes with cysteine by adding cupric ions, and then derived with sodium tetraphenylborate. Under the optimal chromatographic conditions, MeHgPh and EtHgPh, the resulting derivatives, were separated completely on a DB-5MS capillary column and detected by electron impact ionization mass spectrometry in the selective ion monitoring (SIM) mode, and quantified by a stable isotope dilution method using the d3-methylmercury as internal standard. The calibration curves were linear in the range of 1 500 mu g/L of MeHg and EtHg. Concentration of 0. 828 mg Hg/kg with relative standard deviation (RSD) of 3. 2% (n = 6) was obtained for MeHg in GBW 10029. This was in good agreement with the certified values of (0. 84 +/- 0. 03) mg Hg/kg. The average recoveries were 94% -101% and 81%-104% for MeHg and EtHg spiked in aquatic samples, with RSDs of 1.9% -4.7% and 3.1% -8.2% (n = 6), respectively. The limits of detection (S/N= 3) of the two targets were 0. 1-0. 3 mu g/kg. This method was sensitive, accurate and could meet the demand of the determination of methylmercury and ethylmercury in aquatic products.

• 出版日期2014-10