Solvent demulsification dispersive liquid-liquid microextraction combined with high performance liquid chromatography for determination of methyl parathion in water samples | 溶剂去乳化分散液-液微萃取-高效液相色谱法测定水样中甲基对硫磷

Chinese. 将萃取剂和分散剂的混合液快速注入水样，获得雾化体系，向雾化体系中直接注入乙腈作为去乳化剂促使混合液分相，避免了离心步骤。以三氯乙烯为萃取剂，考察了分散剂体积、萃取剂体积、去乳化剂体积等因素对萃取率的影响。在优化条件下，建立的方法在1～40μg／L质量浓度范围内呈现出良好的线性（R2=0．9998）；对甲基对硫磷的检出限（SIN=3）为0．03ng／mL。建立的方法平行测定5份质量浓度为10ng／mL的甲基对硫磷水样，相对标准偏差为3．3％。本方法已成功用于实际水样分析，平均回收率为73．9％～84．8％。

English. A new method of solvent demulsification dispersive liquid-liquid microextraction （SD- DLLME） was developed for the determination of methyl parathion in the water samples by high per- formance liquid chromatography （HPLC）. In the extraction procedure, a mixture of extraction solvent （trichloroethylene） and dispersive solvent （methanol） was injected into the aqueous sample solution to form an emulsion. In contrast with the conventional DLLME methods,which usually obtained the phase separation through centrifugation,a demulsification solvent （acetonitrile） was injected into the sample tube to break up the emulsion. The dispersed system turned clear quickly. The subnatant （trichloroethyl- ene） was collected and analyzed by HPLC. No centrifugation was required in this procedure. Factors affecting the extraction efficiency such as the type and volume of dispersive solvent, extraction solvent and de-emulsifier were investigated in detail. Under the optimized conditions, the proposed method provided a good linearity in the range of 1-40 ng/mL （R2 =0. 999 8）. The detection limit （S/N =3） was 0. 03 ng/mL. The relative standard deviations （RSDs） for the determination of 10 ng/mL methyl parathion was 3.3% （n=5）. The proposed method is fast, efficient, convenient and can be successfully applied to the extraction of methyl parathion in natural water samples.