Método multirresíduo para determinação de micotoxinas em vinho por UPLC-MS/MS

Abstract

A fast multimethod using liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was implemented and optimized to yield a complete determination of 36 mycotoxins in wine samples. Extraction was performed with acetonitrile, applying modified QuEChERS method (Quick, Easy, Cheap, Effective, Rugged and Safe). Traditionally, QuEChERS method is well known in pesticides determination in a variety of matrices and due this has received the distinction of an AOAC (Association of Official Agricultural Chemists) official method for multiple pesticides in fruits and vegetables (LEHOTAY et al., 2005; BANERJEE et al., 2009). Usually mycotoxins analysis are carried out by liquid chromatography after immunoaffinity column clean-up or by enzyme-linked immunosorbent assay tests, but all these methods normally involve determination of a single compounds only (SPANJER et al., 2008; CUNHA et al., 2009). This study aimed to apply modified QuEChERS method as extraction procedure for mycotoxins determination in wine samples.During this study, were performed optimization experiments to improve recovery results and analites stability. Besides the evaluation of the proper volume of wine samples to be applied, tests were performed to test pH effect by using an additional buffering step with ammonium formate/ formic acid. Normally this method apply a dispersive clean-up with sorbents to clean-up sample extract. This procedure followed a dSPE clean-up with various sorbents where mycotoxins were analyzed on UPLC-MS/MS system, using electrospray ionization in positive mode. Mycotoxins standards stock solutions were prepared and classified in three different groups, with different range of concentration. Recovery studies were performed by analyzing samples in three spiked levels, with six (n=6) replicates in each concentration. Other validation parameters evaluated were linearity (r2) of calibration curves, accuracy (recovery %), instrument limits of detection and method limits of quantification (LOD and LOQ), precision (RSD%) and matrix effects (%) were determined for each individual mycotoxin. From 36 mycotoxins analyzed by UPLC-MS/MS (ESI+), 35 showed average recoveries between 70-120% and 88% an RSD ≤ 20%, at the lowest spiked level (Group I = 1, Group II = 50 e Group III = 10 μg kg-1). The method LOQ for 86% mycotoxins was the lowest level studied. The observed matrix effect was lower than ±20% for 75% of mycotoxins. This procedure was applied successfully also in a survey of 56 red wine samples purchased in the city of Amsterdam (The Netherlands) from many different countries.