NC-100大孔树脂对速溶茶农药残留的降解作用

Degradation of Pesticide Residues in Instant Tea by NC-100 Macroporous Resin

摘要:

本研究对速溶茶溶解液中5种农药残留的树脂吸附效果进行了研究，通过静态吸附试验比较了两种树脂对速溶茶溶解液中农药残留和茶多酚的吸附特性，筛选出具有良好吸附率的NC-100树脂。利用正交试验统计法确定了动态吸附的最佳吸附参数：上样流速3.0 BV/h、pH为5、温度为80 ℃和浓度为100 mg/mL，在该工艺条件下5种农药去除率可达75.1%~90.4%，而茶多酚损失率为17.6%。建立的农药检测方法具有良好的准确性和精密度，五种农药在0.2~50 μg/L内线性关系良好，相关系数大于0.995，该方法定量限为0.01 mg/kg，对空白茶粉添加0.01 mg/kg和0.04 mg/kg两个浓度水平的农药，平均回收率均在76.4%~114.5%，相对标准偏差均在2.3%~4.8%（n=3），以检测方法为基础，通过对过程及结果的全面分析，探索吸附机理，为将树脂应用于去除速溶茶中农药残留提供理论和实践基础。

Abstract:

In this study, the resin adsorption effect on the 5 kinds of pesticide residues in instant tea solutions was studied. Through the comparison on the adsorption properties of two macroporous resins for pesticides residues and tea polyphenols of instant tea solutions by static adsorption experiments, the NC-100 resin with higher adsorption rate was screened out. The optimal adsorption parameters of dynamic adsorption were determined by the orthogonal experimental design and statistical method: sample flow rate was 3.0 BV/h, pH was 5, temperature was 80 ℃, and concentration was 100 mg/mL. Under such process conditions, the removal rates for the five kinds of pesticides reached 75.1%~90.4%, with the loss rate of tea polyphenols being 17.6%. The established detection method for pesticides has good accuracy and precision, with a good linearity in the range of 0.2~50 μg/L, correlation coefficient (r2) higher than 0.995, and limit of quantification as 0.01 mg/kg. After pesticide was spiked at 0.01 or 0.04 mg/kg into the blank tea powder, the recovery rates were 76.4%~114.5% with relative standard deviations (RSD) as 2.3%~4.8% (n=3). Based on the detection method and comprehensive analysis of the process and results, the adsorption mechanism was examined to provide a theoretical and practical basis for the application of resin to removing the pesticide residues in instant tea.