气相色谱-负化学源质谱法测定河蟹中五氯苯酚及其钠盐的残留量

Determination of the residue amount of pentachlorophenol and its sodium salt in Eriocheir sinensis by gas chromatography-negative chemical ionization/mass spectrometry

目的测定河蟹可食部分中五氯苯酚及其钠盐的残留量。方法样品在酸性介质中经正己烷提取、HLB固相萃取柱净化后,用甲醇洗脱,吹干后用碳酸钾溶液溶解,经衍生化反应生成的衍生物由正己烷提取,采用选择离子监测模式进行质谱测定。选择^(13)C_6-PCP作为内标物,通过对离子源及其温度、定性离子和定量离子的选择,建立气相色谱-负化学源质谱法测定河蟹可食部分中五氯苯酚及其钠盐残留量的检测方法。结果五氯苯酚乙酸酯在0.2~20.0μg/L范围内的线性关系良好,相关系数r=0.999,五氯苯酚在添加水平为5.0、10.0和50.0μg/kg时的平均回收率在87.2%~96.9%之间,测定相对标准偏差(n=6)在2.8%~6.3%之间,方法检测限为1.0μg/kg。结论该方法的检测准确度和精密度良好,能够用于河蟹样品中五氯苯酚及其钠盐残留的定性与定量测定。

Objective To detect the residue amount of pentachlorophenol and its sodium salt in the eatable part of Eriocheir sinensis.Methods The samples were extracted by n-hexane in anacidic medium,purified by HLB solid phase extraction column,and eluted with methanol.The product was dissolved with K2CO3 after being concentrated by drying,and the derivative of above product was extracted by n-hexane which was analyzed by mass spectrometry using selected ion monitoring mode.A gas chromatography-negative chemical ionization/mass spectrometry method was established through the selection of ion source and its temperature,qualitative ion and quantitative ion when using ^13C6-PCP as an internal standard substance,which could realize the determination of the residue amount of pentachlorophenol and its sodium salt in the eatable part of Eriocheir sinensis.Results The working curve of PCP-OAc had a good linearity when the concentration was between 0.2 μg/L and 20.0 μg/L,and the correlation coefficient（r） was 0.999.The average recoveries were in the range of 87.2%-96.9%when the additive amounts of pentachlorophenol were 5.0,10.0 and 50.0 μg/kg,respectively.The relative standard deviations（n=6）were in the range of 2.8%-6.3%,and the limit of detection was 1.0 μg/kg.Conclusion The method is accurate and precise,which can be used to the qualitative and quantitative determination of the residue amount of pentachlorophenol and its sodium salt in the eatable part of Eriocheir sinensis.