水相衍生-气相色谱-质谱法同时测定水产品中甲基汞和无机砷

建立了同时测定水产品中甲基汞和无机砷的水相衍生-气相色谱-质谱联用分析方法。采用6 mol/L盐酸超声辅助提取水产品中的甲基汞与无机砷，于-10℃冷冻离心后，提取液中的无机砷（As³⁺与As⁵⁺）与2，3-二巯基丙醇（BAL）溶液于35℃水浴中衍生反应30 min，用甲苯萃取衍生物与甲基汞，萃取前加入无水乙醇避免非脂成分进入有机相中，向甲苯萃取液中添加甲基汞的衍生剂四苯硼钠溶液（pH 3.6）。采用选择离子监测（SIM）模式，外标法测定水产品中的甲基汞与无机砷。结果表明，水产品中甲基汞与无机砷在5～2000 μg/L范围内线性关系良好，相关系数（r）均大于0.999；检出限为0.7～3 μg/kg （S/N=3）。在10、100、1000 μg/kg加标水平下，方法加标回收率为80.0%～110.0%，相对标准偏差（n=6）为2.5%～9.4%。该方法操作简便、准确、灵敏度高，已成功应用于水产品中无机砷与甲基汞的食品污染物风险监测中。

Simultaneous determination of methylmercury and inorganic arsenics in aquatic products by gas chromatography-mass spectrometry with aqueous derivatization

A fast analytical method based on gas chromatography-mass spectrometry (GC-MS) with aqueous derivatization was established for the simultaneous determination of methylmercury and inorganic arsenics in aquatic products. Methylmercury and inorganic arsenics in samples were extracted with hydrochloric acid (6 mol/L) by ultrasonic extraction. After centrifugation at -10℃, inorganic arsenics (As³⁺ and As⁵⁺) were derivatized under 35℃ water bath for 30 min with 2,3-dimercapto-1-propanol (BAL), then the derivative and methylmercury were extracted with toluene. The non-fatty components in the hydrochloric acid extract were avoided to get into the toluene by adding absolute ethanol before extraction, so the tested solution was purified. Then sodium tetraphenylborate solution (pH 3.6) was added to toluene extraction solution as the derivatization reagent. After centrifugation, the derivatives in organic phase were determined by GC-MS with selected ion monitoring (SIM) mode, and quantified with external standard method. The results showed that the calibration curves were linear in the range of 5-2000 μg/L for methylmercury and inorganic arsenic with correlation coefficients (r) greater than 0.999, and the limits of detection (LODs) were 0.7-3 μg/kg (S/N=3). The recoveries were 80.0%-110.0% at three spiked levels (10, 100, 1000 μg/kg), and the relative standard deviations (RSDs) were 2.5%-9.4% (n=6). The new method is simple, accurate and sensitive, and it has been successfully applied to the determination of methylmercury and inorganic arsenics in real aquatic products for the risk monitoring of food pollutants.