气相色谱方法同时测定果蔬及粮谷中6种除草剂残留

Simultaneous determination of 6 herbicides in vegetables,fruits and cereals by gas chromatography

建立了一种同时测定果蔬、粮谷中6种除草剂（氟乐灵、2,4-D丁酯、乙草胺、甲草胺、异丙甲草胺、丁草胺）的QuEChERS-GC方法。果蔬样品采用乙腈提取,用5g无水硫酸镁和3g氯化钠除水和盐析,再混合使用175mg乙二胺-N-丙基硅烷（PSA）、25mg十八烷基硅烷（C18）、60mg石墨化炭黑（GCB）和500mg无水硫酸镁作为吸附剂,净化4min;粮谷样品采用乙腈提取,用5g无水硫酸镁和3g氯化钠除水和盐析,再混合使用250mg PSA、200mg C18和500mg无水硫酸镁作为吸附剂,净化3min;净化液浓缩后采用DB-1701色谱柱（30m×0.25mm,0.25μm）分离,ECD检测。实验通过空白基质溶液稀释标准品建立校正的标准曲线,以消除基质效应。结果表明,6种除草剂在各自相应的浓度范围内具有良好的线性关系,相关系数均大于0.999,样品加标回收率为84.05%-104.85%,相对标准偏差为2.02%-8.28%,方法的检出限在0.002-0.03μg/mL之间,定量限在0.002-0.02mg/kg之间。方法操作简便、快速、准确,可满足蔬菜水果和粮谷中除草剂的分析要求。

A QuEChERS-GC method was developed for the simultaneous determination of 6 herbicides including trifluralin, 2,4-D butylate, acetochlor, alachlor, metolachlor and butachlor in vegetables, fruits and cereals. The analytes were extracted from the vegetables and fruits using acetonitrile and removed water using 5g MgSO4 and salted out using 3g NaCl,and then cleaned up with 175mg PSA,25mg C18,60mg GCB and 500mg MgSO4 for 4 minutes. The analytes were extracted from the cereals using acetonitrile and removed water using 5g MgSO4 and salted out using 3g NaCl,and then cleaned up with 250mg PSA,200mg C18 and 500mg MgSO4 for 3 minutes. The purified sample solution after concentrating was separated by a DB-1701 （30m×0.25mm, 0.25μm） and detected by GC with ECD detector. The calibration standard curve was established using the standard solution diluted with the blank matrix solution. The results showed the liner ranges of six herbicides were well with correlation coefficient above 0.999. The average recoveries were 84.05%-104.85% and the relative standard deviations ranged from 2.02%-8.28%. The limits of detection were ranged from 0.002μg/mL to 0.03μg/mL and the limit of quantification from 0.002mg/kg to 0.02mg/kg. This method was simple ,accurate and sensitive to herbicides in vegetables ,fruits and cereals.