提出了液相色谱-串联质谱法测定蔬菜及其制品中苯霜灵、灭多威、扑灭津、哒螨灵及吡螨胺等5种农药残留量的方法。蔬菜样品经含0.1%(体积分数)乙酸的乙腈及无水硫酸镁和无水乙酸钠提取并离心分离后,取上清液蒸干,用乙酸酸化的乙腈2 mL溶解。将此溶液加入于PSA、C18与石墨碳黑混合吸附剂粉末中经涡旋混合的分散固相净化方法净化。以Hypersil GOLD-C18色谱柱为分离柱,以不同体积比的(A)甲醇和(B)甲酸-水(1+9)的混合液为流动相进行梯度洗脱,洗脱液用乙腈-水(2+8)混合液定容,进行MS测定。采用电喷雾负离子源多反应监测模式检测。5种农药在一定的质量浓度范围内与其峰面积呈线性关系,方法的检出限(3S/N)均为0.01 mg·kg-1。加标回收率在86.1%~95.7%之间,测定值的相对标准偏差(n=6)在1.2%~3.8%之间。

A method of LC-MS/MS for the determination of residual amounts of 5 pesticides, i.e. benalaxyl, methomyl, propazine, tebufenpyrad and pyridaben in vegetable and its products was proposed. The sample was extracted with a mixture of acetonitrile (containing φ 0.1% of acetic acid) and anhy. MgSO4 as well as anhy. NaOAc. After centrifugation, the supernatant was evaporated to dryness and dissolved with 2 mL of the CH3CN acidified with CH3COOH. The solution was then purified by dispersive-SPE through mixing vortically with PSA, C18 and graphite carbon black. The supernatant was taken and separated on Hypersil GOLD-C18 column using mixtures of (A) methanol and (B) mixture of formic acid and H2O (1+9) with different ratio as mobile phase by gradient elution. The eluate was made up to definite volume and used for MS determination. ESI- and MRM were adopted in MS/MS. Linear relationships between values of peak area and mass concentration of the 5 pesticides were kept in definite ranges, with the same detection limit (3S/N) of 0.01 mg·kg-1. Tests for recovery were made by standard addition method, giving values of recovery and RSD′s (n=6) in the ranges of 86.1%-95.7% and 1.2%-3.8% respectively.