二氯甲烷萃取气相色谱法测定生活饮用水中的2,4-滴和灭草松

Determination of 2,4-D and Bentazone in Drinking Water by Gas Chromatography with Dichloromethane Extraction

目的建立用二氯甲烷萃取生活饮用水中2,4-二氯苯氧乙酸(2,4-滴)和灭草松,毛细管柱气相色谱电子捕获检测器(GC-ECD)测定其浓度的方法。方法利用经典的液液萃取技术,选择最佳的衍生化温度反应条件,应用气相色谱法测定水样中2,4-滴和灭草松。结果以10倍信噪比计,2,4-滴的最低检测质量浓度为0.5μg/L,灭草松的最低检测质量浓度为0.7μg/L;工作曲线相关系数r≥0.999;二氯甲烷萃取2,4-滴和灭草松回收率分别在82.0%~89.6%与91.1%~94.4%之间,相对标准偏差在1.3%~2.3%与0.36%~1.7%之间。在10℃~15℃之间衍生化的2,4-滴和灭草松响应值明显高于15℃~20℃之间(P<0.05)。结论用二氯甲烷进行液液萃取,在10℃~15℃之间进行衍生,方法灵敏度和精密度均能满足分析要求。

Objectives To develop an analytical method for 2,4-dichlorophenoxyacetic acid( 2,4-D) and bentazone in drinking water by using dichloromethane extraction and gas chromatography. Methods The amounts of 2,4-D and bentazone in water samples were detected by dichloromethane extraction and capillary column gas chromatography with electron capture detector through controlling the temperature of derivatization. Results The working curves for 2,4-D and bentazone detection showed good linearity in the range of 0. 5 ~ 25. 0 μg / L and 0. 7 ~ 25. 0 μg / L respectively,with a correlation coefficient of 0. 999. The minimum detection concentration for 2,4-D was 0. 5 μg / L and that for bentazone was 0. 7 μg / L. The recoveries of 2,4-D and bentazone at three spiking levels were in the range of 82. 0% ~ 89. 6% and 91. 1% ~ 94. 4% respectively,and RSDs were in the range of 1. 3% ~ 2. 3% and 0. 36% ~ 1. 7%,respectively. The response value in 10℃ ~ 15℃ was obviously better than that in 15℃ ~ 20℃( P < 0. 05). Conclusions The sensitivity and precision of the method on detecting 2,4-D and bentazone in water by dichloromethane extraction and derivatization between 10℃ and 15℃ could meet the requirement of the national standard.