提出了基于低共熔溶剂(DES)修饰磁性碳纳米管的分散固相萃取-高效液相色谱法测定4种杀菌剂残留量的方法。将氯化胆碱与乙二醇按物质的量比1∶2混合,用磁力搅拌器涡旋加热直到获得透明的DES,再用2 mL DES和0.4 g磁性碳纳米管制备DES修饰磁性碳纳米管。取5 mL水置于离心管中,加入200 μL果汁样品和16 mg DES修饰磁性碳纳米管,超声提取10 min,在外加磁场作用下沉淀30 min,去除上层液体,再加入1 mL乙醇,涡旋2.5 min,过0.22 μm滤膜,采用高效液相色谱法测定滤液中异菌脲、氯苯嘧啶醇、腈菌唑、醚菌酯等4种杀菌剂的含量。结果表明,4种杀菌剂的质量浓度在0.5~5.0 mg·L^-1内与对应的峰面积呈线性关系,检出限(3S/N)依次为0.04,0.11,0.15,0.16 mg·L^-1。按照标准加入法进行回收试验,回收率为81.5%~98.9%,测定值的相对标准偏差(n=6)均小于7.0%。

A method for the determination of residues of 4 fungicides by high performance liquid chromatography (HPLC) with dispersion solid phase extraction based on magnetic carbon nanotubes modified with deep eutectic solvent (DES) was proposed. Choline chloride and glycol were mixed at the molar ratio of 1∶2, which was heated by vortex with a magnetic agitator until the transparent DES was obtained. Magnetic carbon nanotubes modified with DES were prepared with 2 mL of DES and 0.4 g of magnetic carbon nanotubes. 5 mL of water was taken and placed in a centrifuge tube, and 200 μL of fruit juice sample and 16 mg of magnetic carbon nanotubes modified with DES were added. The mixture was extracted by ultrasound for 10 min and precipitated for 30 min under external magnetic field. The upper liquid was removed and 1 mL of ethanol was added. After vortex for 2.5 min, the mixture was passed through a 0.22 μm filter membrane. Four fungicides, including iprodione, fenarimol, myclobutanil, and kresoxim-methyl, in the filtrate were determined by HPLC. As shown by the results, linear relationships between values of mass concentration of 4 fungicides and the corresponding peak area were found in the range of 0.5-5.0 mg·L^-1, with detection limits (3S/N) of 0.04 mg·L^-1 for iprodione, 0.11 mg·L^-1 for fenarimol, 0.15 mg·L^-1 for myclobutanil and 0.16 mg·L^-1 for kresoxim-methyl, respectively. Test for recovery was made by the standard addition method, giving results in the range of 81.5%-98.9%, with RSDs (n=6) of the determined values less than 7.0%.