双填料固相萃取-紫外分光光度法检测茶汤中农药残留

以沉淀聚合法制备溴氰菊酯和吡虫啉分子印迹聚合物,然后干法裝柱制备双填料固相萃取柱考察其吸附性能,利用紫外分光光度计确定溴氰菊酯和吡虫啉的最大吸收波长,采用扫描电子显微镜对聚合物进行表征。实验结果表明溴氰菊酯在220 nm处吸收峰较大,而吡虫啉在270 nm处有最大吸收峰,且两种聚合物均具有较好的吸附能力。溴氰菊酯和吡虫啉在10~60 mg/L浓度范围内线性关系良好(R2>0.99),当以甲醇为活化溶剂、1 mL/min的流速上样、10%乙酸甲醇溶液作为洗脱剂时,该萃取柱对不同茶汤中溴氰菊酯和吡虫啉的加标回收率分别为83.15%~110.19%和80.61%~90.73%。对萃取柱8次重复利用结果证明该双填料萃取柱具有较好的再生性,可应用于茶叶中溴氰菊酯和吡虫啉农药的定量检测。

Determination of Pesticide Residues in Tea Broth by Solid Phase Extration Column of Dual Packing Materials with UV Spectrophotometry

The molecularly imprinted polymers of deltamethrin and imidacloprid were prepared by precipitation polymerization,and then the dry-packing column was used to prepare the solid phase extraction on dual packing materials column to investigate the purification effect of adsorption analysis. The maximum absorption wavelength of deltamethrin and imidacloprid were detected by UV spectrophotomete,and the two polymers were characterized by scanning electron microscopy. The experimental results showed that the absorption peak of deltamethrin at 220 nm was larger,and the maximum absorption peak of imidacloprid at 270 nm. Furthermore,the both polymers had good adsorption capacity. The linear relationship of deltamethrin and imidacloprid in the concentration range of 10~60 mg/L were better(R2>0.99). When the methanol as the activation solvent at a flow rate of 1 mL/min and 10% acetic acid methanol solution as the eluents. The spiked recoveries of deltamethrin and imidacloprid in different tea broth were 83.15%~110.19% and 80.61%~90.73%,respectively. The results of 8 repeated use of the extraction column proved that the solid phase extraction on dual packing materials column had good regenerability,which could be applied to the quantitative detection of deltamethrin and imidacloprid pesticides in tea.