同位素稀释-液相色谱-串联质谱法测定奶粉中五氯苯酚

Determination of Pentachlorophenol in Milk Powder by Isotope Dilution Liquid Chromatography-Tandem Mass Spectrometry

建立同位素稀释-液相色谱-串联质谱法测定奶粉中五氯苯酚的分析方法。样品用水溶解,以乙腈为提取试剂和蛋白沉淀剂,QuEChERS法萃取,Captiva EMR-Lipid脂质去除净化柱净化,净化液与水按体积比1∶1稀释后制得待测液。以甲醇和5 mmol/L乙酸铵溶液(含0.05%甲酸)为流动相,梯度洗脱,Waters ACQUITY BEH C18色谱柱(100 mm×2.1 mm,1.7μm)分离,电喷雾负离子多反应监测模式检测,采用基质匹配结合同位素稀释内标法定量。结果表明:五氯苯酚在0.2~150μg/L范围内具有良好线性关系(r≥0.9960);方法检出限为0.5μg/kg,定量限为1.5μg/kg;平均加标回收率为90.3%~119.2%,相对标准偏差不高于7.5%。建立的前处理方法无需浓缩、复溶等步骤,具有前处理简便、灵敏度高、准确可靠等优点,可作为奶粉样品中五氯苯酚检测的有效手段。

In this study,an analytical method was established to determine pentachlorophenol(PCP)in milk powder by isotope dilution-liquid chromatography-tandem mass spectrometry(LC-MS/MS).The sample was dissolved in water,extracted by the quick,effective,cheap,easy,rugged and safe(QuEChERS)method using acetonitrile as the extraction solvent and protein precipitant,purified on a Captiva EMR-Lipid column,and diluted with the same volume of water before analysis.The chromatographic separation was achieved on a C18 column(100 mm×2.1 mm,1.7μm)with gradient elution using a mobile phase composed of methanol and 5 mmol/L ammonium acetate solution(containing 0.05%formic acid),and then the analyte was detected with negative electrospray ionization(ESI-)in the multiple reaction monitoring(MRM)mode.Matrix matching-isotope dilution internal standard method was used for identification and quantification of the analyte.The results indicated that the calibration curve of PCP was linear in the concentration range of 0.2‒150μg/L with correlation coefficients(r)not less than 0.9960.The limits of detection(LOD)and quantitation(LOQ)of the method were 0.5 and 1.5μg/kg,respectively.The average recoveries for spiked milk powder ranged from 90.3%to 119.2%,with relative standard deviation(RSD,n=6)equal to or less than 7.5%.The method has the advantages of simple pretreatment without concentration or dissolution,high sensitivity,accuracy and reliability,and can be used as an effective method for detecting pentachlorophenol in milk powder.