液相色谱-串联四极杆质谱法测定牛奶中128种农药残留

建立了牛奶中128种农药残留的液相色谱-串联质谱检测方法。10 mL牛奶用20 mL乙腈(加4 g硫酸镁和1 g氯化钠)振荡提取两次,上清液浓缩后经C18固相萃取柱(2000 mg填料)净化以除去提取液中的亲脂性化合物等干扰杂质,洗脱液浓缩至约0.5 mL后,于45 ℃下用氮气吹干,加1 mL乙腈-水(体积比为3:2)定容,超声溶解30 s,经0.2 μm微孔滤膜过滤,液相色谱-电喷雾串联质谱测定。2倍检出限和8倍检出限两个添加水平的5次平行实验结果表明: 128种农药在低添加水平(0.14 μg/L～0.62 mg/L)下回收率范围为60.4%～118.4%,相对标准偏差为2.1%～24.3%;高添加水平(0.56 μg/L～2.48 mg/L)下的回收率范围为64.4%～118.5%,相对标准偏差为1.3%～24.1%。各种农药在确定的添加范围内线性关系良好,相关系数高于0.99,方法的检出限(LOD)为0.07 μg/L～0.31 mg/L。该方法通用性强、选择性好、灵敏度高,快速简便。

Simultaneous determination of 128 pesticide residues in milk by liquid chromatography-tandem electrospray mass spectrometry

A method has been developed for the simultaneous determination of 128 pesticide residues in milk by liquid chromatography-tandem electrospray mass spectrometry (LC-ESI-MS/MS). A total of 10 mL milk was extracted with 20 mL acetonitrile (plus 4 g magnesium sulfate and 1 g NaCl) for two times. The concentrated supernatant was cleaned-up by a C18 solid phase extraction cartridge to remove the lipophilic compounds. The eluate was concentrated to about 0.5 mL in 45 ℃ water bath with nitrogen. The 1 mL mixture of acetonitrile and water (3:2, v/v) was added into the sample and mixed thoroughly for 30 s. The sample solution was filtered by 0.2 μm millipore filters before LC-ESI-MS/MS determination. This method was evaluated at the two spiked levels of 2 times and 8 times of limits of the detection (LODs) in 5 parallel experiments, respectively. The results showed that the average spiked recoveries of 128 pesticides at the low spiked level (0.14 μg/L~0.62 mg/L) were from 60.4% to 118.4% with relative standard deviations (RSDs) of 2.1%~24.3%, and the average spiked recoveries at the high spiked level (0.56 μg/L~2.48 mg/L) were from 64.4% to 118.5% with the RSDs of 1.3%~24.1%. The method showed a good linear relationship with the correlation coefficients over 0.99. The LODs were from 0.07 μg/L to 0.31 mg/L. This method is selective, accurate and easy to operate.