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.