Development and Validation of a Multi-residue Method for the Determination of Pesticides in Chios Mastic Gum by QuEChERS and Liquid Chromatography–Tandem Mass Spectrometry

Abstract

A simple, rapid, and sensitive method was developed for the simultaneous determination of 21 pesticides from different chemical classes (organophosphorus, triazines, carbamates, and anilinopyrimidine pesticides) in Chios mastic gum (Pistacia lentiscus L. var. Chia). Quick, easy, cheap, effective, rugged, and safe (QuEChERS) technique was used for the extraction of the target analytes; the mastic gum samples were initially extracted with acetonitrile (ACN), and then, the extracts were purified by dispersive solid-phase extraction using primary secondary amine (PSA) and C18 as sorbents. The determination of pesticides in the final extract was carried out by liquid chromatography coupled with tandem mass spectrometry with electrospray ionization (LC-ESI-MS/MS). The method was validated for linearity, accuracy, precision (repeatability and inter-laboratory reproducibility), limits of detection and quantification, and the matrix effect factor. Recoveries of the pesticides fortified at 5, 50, and 500 ng g−1 ranged from 49.7 % (quinalphos) to 127 % (pirimiphos-ethyl) and reproducibility (RSDR, n = 2 × 3) ranged from 4.4 % (propham) to 20 % (pirimiphos-methyl, propham, and triazophos). The detection limits of the method were 0.8 (mecarbam, pyrazophos) to 23 ng g−1 (parathion-ethyl). The uncertainty of the method was also calculated based on the Eurachem/Citac Guidelines, and the contribution of each independent parameter was investigated.