高效液相色谱-串联质谱法测定草莓中的4-氯苯氧乙酸和2,4-二氯苯氧乙酸

Determination of 4-Chlorophenoxyacetic Acid and 2,4-Dichlorophenoxyacetic Acid in Strawberry by Liquid Chromatography-Tandem Mass Spectrometry

建立了草莓中4-氯苯氧乙酸和2,4-二氯苯氧乙酸的高效液相色谱-串联质谱检测方法。样品前处理采用Qu ECh ERS方法,以乙腈振荡提取,加入无水Mg SO4、Na Cl、二水合柠檬酸钠和柠檬酸氢二钠（1.5水）,促进乙腈与水液液分离。提取液以对丙基苯磺酸基吸附剂（SCX）吸附花色苷,结合C18填料和无水Mg SO4分散固相萃取净化。采用C18色谱柱分离,甲醇和0.1%甲酸水溶液洗脱,多反应监测负离子模式扫描分析。两个目标物在0.025~1.0 mg/L范围内,线性关系良好,R2〉0.999,检出限（LOD,S/N=3）为0.005 mg/kg,方法的定量下限（LOQ,S/N=10）为0.015 mg/kg,加标回收率为85.3%~95.4%,日内精密度为1.1%~6.9%,日间精密度为2.0%~8.7%。该方法稳定、可靠,可满足草莓中两个目标物的检测要求。

A modified Qu ECh ERS method for the determination of 4-chlorophenoxyacetic acid and 2,4-dichlorophenoxyacetic acid in strawberry was developed by using liquid chromatography-tandem mass spectrometry. The modified Qu ECh ERS sample preparation procedure involved an initial extraction of sample with acetonitrile, followed by liquid-liquid partitioning formed by adding anhydrous Mg SO4, Na Cl, trisodium citrate dihydrate and disodium hydrogen citrate sesquihydrate. The acetonitrile extract was cleaned up by dispersive solid-phase extraction（d-SPE） with anhydrous MgSO4, C18 and a strong cation-exchange（SCX） sorbent which was used for the removal of strawberry anthocyanins. The separation of the two analytes was performed on a C18 column with 0.1% formic acid aqueous solution and methanol as mobile phase. The analysis was carried out on a tandem mass spectrometer in multiple reaction monitoring（MRM） mode with negative electrospray ionization. The calibration curves were linear with correlation coefficients over 0.999. The limits of detection（LODs, S/N = 3） for the two analytes were 0.005 mg/kg, the limits of quantification（LOQs, S/N = 10）,0.015mg/kg. The average spiked recoveries were between 85.3% and 95.4%, with the ranges of intra-day and inter-day relative standard derivations（RSDs） being 1.1%~6.9% and 2.0%~8.7% respectively.