Quantificação de micotoxinas e resíduos de fungicidas em grãos de trigo por LC-QTOF-MS

Abstract

Wheat (Triticum aestivum) is globally one of the most consumed cereal and is subjected to contamination by mycotoxins and fungicides. Mycotoxins are metabolites derived from specialized metabolism of filamentous fungi, the main belonging to the genus Fusarium, Penicillium and Aspergillus, which are responsible for the production of fumonisin, zearalenone (ZEA), deoxynivalenol (DON), ochratoxin and aflatoxin. The aim of this study was to evaluate an analytical LC-ESI-QTOF-MS method for simultaneous determination of mycotoxins and fungicide residues in wheat grains. Wheat plants were treated with Fox (trifloxystrobin and prothioconazole), Opera (epoxiconazole and pyraclostrobin) and Unizeb Gold (mancozeb) fungicides, separately and in combination. All parameters (linearity, detection and quantification limits, accuracy, precision, specificity, selectivity and matrix effect) for the validation of the analytical method and quantification were in accordance with the rules of the AOAC, ANVISA and SANCO. For simultaneous extraction of mycotoxins (aflatoxins B1, B2, G1, G2, deoxynivalenol, fumonisin B1, ochratoxin A and zearalenone) and fungicides (trifloxystrobin, prothioconazole, pyraclostrobin, epoxiconazole and mancozeb) was used QuEChERS method. In general, the epoxiconazole and DON were found in higher concentrations. The mancozeb could not be detected by LC-ESI-QTOF-MS method, due to polymer characteristics that makes its solubilkization hard. Evaluating a possible relation between the applied fungicides with mycotoxin content it can be observed that the fungicides trifloxystrobin, prothioconazole, epoxiconazole, pyraclostrobin and mancozeb, applied both separately and as a mixture, may have stimulated the production of AFB2; the active ingredients trifloxystrobin, prothioconazole and mancozeb may have presented stressor effect to the fungus, stimulating the production of ZEA; while the use of epoxiconazole, pyraclostrobin and mancozeb fungicides may be associated with OTA production. The AFB1 and DON molecules were found in lower concentrations in all treatments, as compared to the control sample, except for the treatment with mancozeb, in which the concentration of DON increased by 11%.