Quantitative Screening of Agrochemical Residues in Fruits and Vegetables by Buffered Ethyl Acetate Extraction and LC-MS/MS Analysis

A buffered ethyl acetate extraction method is proposed for the simultaneous analysis of 296 agrochemicals in a wide range of fruit and vegetable matrices by liquid chromatography–tandem mass spectrometry (LC-MS/MS). The optimized quantity of acetate buffer (1% acetic acid + 0.5 g of sodium acetate per 10 g of sample) adjusted the pH of each test matrix to 5–6, which in turn significantly improved recoveries of acidic and basic compounds. The role of diethylene glycol (used in the evaporation step) on signal suppression of certain compounds was evaluated, and its quantity was optimized to minimize such an effect. The method was validated in grape, mango, drumstick, bitter gourd, capsicum, curry leaf, and okra as per the DG-SANCO/12571/2013 guidelines. Recoveries in the fortification range of 1–40 μg/kg were within 70–120% with associated relative standard deviations below 20% for most of the compounds. The method has potential for regulatory and commercial applications with a generic approach.本研究提出一种缓冲乙酸乙酯萃取法，可借助液相色谱-串联质谱（liquid chromatography–tandem mass spectrometry, LC-MS/MS）同时分析多种果蔬基质中的296种农用化学品。经优化的乙酸盐缓冲液（每10g样品添加1%乙酸与0.5g乙酸钠）可将各待测基质的pH值调节至5~6，进而显著提升酸性与碱性化合物的回收率。本研究评估了二甘醇（diethylene glycol）在蒸发步骤中对部分化合物的信号抑制作用，并对其添加量进行优化以最小化该负面影响。本方法按照DG-SANCO/12571/2013指南，在葡萄、芒果、辣木荚、苦瓜、辣椒、咖喱叶及秋葵基质中完成了方法验证；在1~40 μg/kg的加标浓度范围内，绝大多数化合物的回收率处于70%~120%区间，对应的相对标准偏差均低于20%。本方法采用通用化分析策略，具备监管与商业应用潜力。