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