Monitoring of non-systemic and systemic pesticides and date (Phoenix dactylifera L.) fruit metabolites using DESI-TOF MS.

A desorption electrospray ionization-time of flight mass spectrometry (DESI-TOF MS) method was developed for monitoring eight non-systemic and systemic pesticides from five major chemical classes of organophosphates, along with their metabolites and major putative endogenous metabolites-including sugars, lipids, and polyphenols-in both the peel and flesh of Mazafati dates. The limits of detection were 0.10 for diazinon, 0.33 for chlorpyrifos, and 1.00 μg kg-1 for the other pesticides. LC-MS/MS combined with QuEChERS extraction was used for comparison with DESI-TOF MS and reduced solvent consumption and a significant decrease in total analysis time-from 90 min to 3 s-along with simultaneous determination of putative metabolites of pesticides and dates are key advantages of the proposed method. Also, the reduction of non-systemic pesticide residues by water washing was investigated. Water washing led to a residue reduction in the date peel in the following order: chlorpyrifos > diazinon > fenitrothion.