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Two simple and low-cost QuEChERS approaches were optimized and validated for multimycotoxin determination in grains by UPLC-MS/MS and applied to assess effectiveness of controlled atmosphere (CA) storage in preventing mycotoxin contamination. Common bean, soybean, and maize samples were stored for 6 months. CA treatments were conducted varying O 2 and CO 2 partial pressures, temperatures, and moisture contents of the chambers. In the validation study for common bean and maize, 8 out of 11 mycotoxins were successfully validated. For soybean, 10 out of 11 mycotoxins were validated. Aflatoxin B1 was detected in all commodities. Statistical tests suggest that storage temperature played a key role in aflatoxin B1 concentrations in common bean and soybean, but had no influence on maize. Maize was also positive for fumonisins B1 and B2. Differences in fumonisin concentrations were not significant among different treatments. Concentrations of aflatoxin B1 in some samples exceeded legislation's maximum levels. Thus, some of the CA treatments applied were effective in preventing mycotoxin contamination in common bean and soybean but were not effective for maize.

Food matrices consist of many components with different physical and chemical properties that may influence instrumental robustness. The soybean contains fatty coextractives which may have a deleterious effect on the gas chromatography (GC) system. In this study, the efficiencies of PSA, C 18 OH, C 18 , silica, aluminum oxide, and Florisil, as dSPE clean-up sorbents, were evaluated by the high-performance liquid chromatography (HPLC) diode-array detector and evaporative light-scattering detector analysis. The dithiocarbamates in soybean samples are determined as CS 2 using acidic hydrolysis and isooctane partitioning, followed by GC-PFPD and GC-ITD-MS analyses. The linearity of the analytical curves, the instrument limit of detection matrix effects, the trueness and precision, and the method limit of quantification (LOQ) were assessed in the validation study. Milled soybean was spiked with thiram solution at three concentration levels (corresponding to 0.05, 0.1, and 0.5 mg CS 2 kg -1 ) for recovery determination. Silica appeared to be an effective and cheap sorbent to remove coextracted matrix components without causing any CS 2 losses. Recoveries were in the range of 68-91%, with relative standard deviations ≤ 8.7%. The method LOQ was 0.05 mg CS 2 kg -1 , and both GC-ITD-MS and GC-PFPD systems appeared to be appropriate and complementary to determine dithiocarbamate residues in soybean extracts.