Determination of Target Pesticide Residues in Tropical Fruits Employing Matrix Solid-Phase Dispersion (MSPD) Extraction Followed by High Resolution Gas Chromatography

A simple method based on matrix solid-phase dispersion (MSPD) extraction and gas chromatography with electron-capture detection (GC-ECD) is employed to determine pesticide residues in the following tropical fruits: banana, mango, melon, papaya and pineapple. In the MSPD proposed method, C18, silica gel and ethyl acetate presented the best results in the extraction, clean-up and elution steps, respectively. Spiked blank samples were used to minimize the matrix effect in the chromatographic determination. The validation process was conducted at three different concentration levels of spiked samples (0.50-2.50 µg g-1) in within-a-day and in among days assays. The limits of detection for the pesticides ranged from 4.0 to 23 µg kg-1. The method showed acceptable selectivity, coefficients of correlation higher than 0.997, and recovery between 76-105%. The within-a-day precision was assessed through the relative standard deviation (2.8-19%) for the different levels of spiked samples tested.

本研究采用一种基于基质固相分散萃取（matrix solid-phase dispersion, MSPD）结合气相色谱-电子捕获检测器（gas chromatography with electron-capture detection, GC-ECD）的简便方法，对香蕉、芒果、甜瓜、番木瓜及菠萝这五类热带水果中的农药残留进行测定。在本研究提出的MSPD方法中，C18填料、硅胶与乙酸乙酯分别在萃取、净化与洗脱步骤中呈现最优效果。为最小化色谱测定过程中的基质效应，实验采用加标空白样品开展分析。验证实验分别于日内与日间条件下进行，设置3个不同的加标浓度水平（0.50~2.50 µg·g⁻¹）。目标农药的检测限介于4.0~23 µg·kg⁻¹之间。该方法具备良好的选择性，相关系数均高于0.997，回收率处于76%~105%的区间内。针对不同加标浓度水平的日内精密度，通过相对标准偏差进行评估，其范围为2.8%~19%。