固相萃取-气相色谱法测定水体中2,4-滴和灭草松的残留量

Determination of Residues of 2,4-D and Benazone in Water Body by Gas Chromatography with Solid Phase Extraction

提出了固相萃取-气相色谱法测定水体中2,4-滴和灭草松残留量的方法。用硝酸将1.0 L水样酸度调至pH小于2,然后以6.0 mL·min-1流量过活化好的HLB pro固相萃取柱,用10.0 mL水淋洗,再用10.0 mL乙酸乙酯洗脱。收集洗脱液,氮吹至近干,加入500μL N,N-二甲基甲酰胺二甲缩醛和1.0 mL正己烷,于160℃衍生50 min。衍生结束后,取出,冷却至室温,加入2.0 mL饱和氯化钠溶液,待分层后,取0.8 mL上层有机相过0.22μm有机相滤膜,滤液按照仪器工作条件进行测定。结果表明:2,4-滴和灭草松的衍生产物分别为2,4-滴甲酯和灭草松甲酯;2,4-滴和灭草松的质量浓度在0.01~0.50 mg·L^(-1)内与对应的衍生产物峰面积呈线性关系,检出限(3.143s)为0.003~0.010μg·L^(-1);对实际加标样品进行精密度试验,测定值的相对标准偏差(n=6)均小于7.0%;生活饮用水、地表水、城镇污水和海水加标样品中,目标物回收率为81.3%~95.4%。

A method for the determination of residues of 2,4-D and benazone in water body by gas chromatography with solid phase extraction was proposed.The acidity of the water sample(1.0 L)was adjusted to pH less than 2 with nitric acid,and then the water sample was passed through activated HLB pro solid phase extraction cartridge at flow rate of 6.0 mL·min^(-1),with rinsing by 10.0 mL of water,and eluting by 10.0 mL of ethyl acetate.The eluent was collected,and blown to nearly dryness by nitrogen,and 500μL of N,N-dimethylformamide dimethyl acetal and 1.0 mL of n-hexane were added for derivation at 160℃for 50 min.After derivative,the solution was taken and cooled to room temperature,and 2.0 mL of saturated sodium chloride solution was added.After stratification,0.8 mL of upper organic phase was taken and filtrated through 0.22μm organic phase filter membrane.The filtrate was determined according to the working conditions of the instrument.It was shown that the derivatives of 2,4-D and benzoate were 2,4-D-methyl ester and benzoate-methyl,respectively.The mass concentrations of 2,4-D and benzoate were linearly related with the corresponding peak areas of derivatives in the range of 0.01-0.50 mg·L^(-1),with detection limits(3.143s)in the range of 0.003-0.010μg·L^(-1).Test for precision was made on the actual samples,and RSDs(n=6)of the determined values were less than 7.0%.In the spiked samples of drinking water,surface water,urban sewage and sea water,the recoveries of the targets were in the range of 81.3%-95.4%.