Multi-mycotoxin analysis of wheat flour by liquid chromatography coupled to triple quadrupole mass spectrometry.

A reliable and rapid method has been developed for the determination of 29 different mycotoxins such as aflatoxins (B1, B2, G1, G2), ochratoxin A, zearalenone, sterigmatocystin, deoxynivalenol, 15- acetyldeoxynivalenol, 3-acetyldeoxynivalenol, nivalenol, fusarenon-X, diacetoxyscirpenol, neosolaniol, HT-2 and T-2 toxins, beauvericin, enniatins (A, A1, B, B1), tenuazonic acid, tentoxin, alternariol, alternariol methyl ether, altenuene, fumonisins (B1, B2, B3) at trace levels in wheat flour. Liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS) was used for their analysis. Extraction and detection conditions were optimized in order to increase sample throughput and sensitivity. Three methods were tested: liquid-liquid extraction, matrix solid phase dispersion and QuEChERS-based extraction procedure. The method chosen consisted on a liquid-liquid extraction of acetonitrile/water (84/16, v/v), which provided the highest recoveries and sensitivity. It was validated for recovery, repeatability, reproducibility, linearity, sensitivity and matrix effect of wheat flour for each analyzed mycotoxin. Method validation was performed by spiking the matrix with standard stock solution of all mycotoxins and depending on the sensitivity, at three different levels from 20 to 300 ng mL-1. Matrixmatched calibration was used for quantification. Recoveries obtained for the 29 mycotoxins were higher than 80%. Repeatability, expressed as relative standard deviation, was always lower than 15%. Good linearity (R > 0.992) was obtained and quantification limits ranged from 2.5 to 60 ng g-1.