Efficiency of ESI and APCI ionization sources in LC-MS/MS systems for analysis of 22 pesticide residues in food matrix.

The intensive use of pesticides has led to the need to optimize analytical methodologies for the control of residues in food. The present study aims to compare the efficiency of different ion sources (Eletrospray Ionization-ESI and Atmospheric Pressure Chemical Ionization - APCI) in LC-MS/MS systems, when analysing 22 pesticides in a cabbage matrix. The method performance was evaluated during a validation study. Organophosphates, triazoles, pyrethroids and triazines compounds showed good linearity in the range 0.5-200 µg.Kg-1. Statistical tests were used to evaluate linearity. LOQm values varied from 0.50 to 1.0 µg.Kg-1 to the ESI source, and 1.0-2.0 µg.Kg-1 for the APCI source. Matrix effect was more intense when using the APCI source. Accuracy and precision were evaluated at three levels of concentration (2; 20 and 100 µg Kg-1). Most of the compounds presented recovery between 70 and 120%. ESI-LC-MS/MS system showed greater efficiency in multiresidue analysis in the cabbage matrix.

Effect of ozonization in degradation of trifluralin residues in aqueous and food matrices.

This study investigates the oxidation of trifluralin residues during ozonation in aqueous and food matrices (tomato). Domestic ozonation equipment with average production of 23.9 mg O3 L-1 h-1 was used in the tests. Modern chromatographic systems (SPME-GC-IT/MS/MS and QuEChERS-GC-IT/MS/MS) were applied for extraction and detection of trifluralin residue in fortified samples of ultrapure water, tap water, superficial water and tomato fruit. The samples were submitted to the ozonation process during 0, 5, 10 and 20 min. Treatment at 5 min was able to degrade 71.5% of herbicide trifluralin in surface water. The removal (%) in ultrapure water reached 83.4% after 20 min of ozonation. The degradation of trifluralin in fortified tomato samples (0.025-0.1 mg kg-1) were conducted with ozonation at 20 min, and it ranged from 84.4 to 92.7%. After treatment, levels of trifluralin in tomato remained within the established MRLs to EU, USEPA and ANVISA (Brazil). The data provided evidence that ozone is effective for removing trace trifluralin from water and foods.