漩涡辅助液液微萃取和气相色谱法分析水样中甲草胺、乙草胺和丁草胺残留

采用漩涡辅助液液微萃取技术作为前处理方法,气相色谱-微池电子捕获检测器作为色谱分析仪器,建立了水样中甲草胺、乙草胺和丁草胺3种酰胺类除草剂的残留分析方法。对影响微萃取效率的各种条件进行了优化,建立的微萃取条件为:在25 mL容量瓶中,依次加入20 mL水样和50 μL甲苯,在2 800 r/min下漩涡1 min。该方法线性范围在0.02 ~5 μg/L之间,相关系数(R2)大于0.997。方法的富集倍数大于500倍。按照信噪比为3时估算的检出限在3.0~4.5 ng/L之间(纯水),方法的报告限为0.05 μg/L(自来水)和0.5 μ/L(雪水)。使用该方法进行了自来水和雪水中的添加回收试验,在0.5,0.05 μg/L添加水平,方法的添加回收率在74.2% ~96.3%之间,相对标准偏差在4.9% ~ 12.1%之间。

Determination of metoalchlor,acetochlor and butachlor residues in water samples using vortex-assisted liquid-liquid microextraction and gas chromatography analysis

A vortex-assisted liquid-liquid microextraction (VALLME) has been developed and used for extraction amide herbicides from water samples,followed by gas chromatography micro-cell electron capture detection (GC-μECD).Experimental factors affecting the extraction efficiency were investigated.For the optimized VALLME method,aliquots of 50 μL toluene used as extraction solvent was directly injected into 20 mL water in a 25 mL volumetric flask.The extraction solvent dispersed into the water phase under vigorously shaking with the vortex.After standing for several minutes,it could be cleared into two phases and easily collected in the volumetric flask for the following GC analysis.Enrichment factors (EF) larger than 500-fold and estimated limits of detection based on the S/N at 3 in a range of 3.0 to 4.5 ng/L were obtained.Lower practical Levels(LPL) were 0.05 μg/L for tap water,0.5 μg/L for snow water.The calculated calibration curves gave linearity with correlation coefficients (R2) greater than 0.997 at the concentration levels ranging from 0.02 to 5.0 μg/L.The proposed method has been successfully validated during the fortification experiments in tap water and snow water with acceptable recoveries ranging from 74.2% to 96.3%,with RSD of 4.9% to 12.1% obtained.