Development and comparison of two multiresidue methods for the determination of 17 Aspergillus and Fusarium mycotoxins in cereals using HPLC-ESI-TQ-MS/MS

Cereals can be contaminated by several mycotoxins, whose co-presence may represent an undervalued risk for humans and animals. Maize and wheat are the most contaminated cereals and in temperate areas could be affected in field conditions by several Fusarium and Aspergillus infections. To date, only B-fumonisins (FBs), aflatoxins (AFs), zearalenone (ZEA), deoxynivalenol (DON) and T-2 and HT-2 toxins have been regulated in cereals in European Union. The other fungal metabolites, are commonly referred to as “emerging” and “masked” mycotoxins, and more information on their occurrence in combination with the regulated mycotoxins, are needed to design combined toxicological and exposure assessments.This research intends to develop and compare two multiresidue HPLC-ESI-TQ-MS/MS methods for the simultaneous determination of the main regulated, emerging and masked mycotoxins in maize and wheat, among which: FB1, FB2, DON, ZEA, AFB1, AFB2, AFG1, AFG2, moniliformin (MON), deoxynivalenol-3-glucoside (DON-3-G), 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON), nivalenol (NIV), enniatins A, A1, B, B1 (ENNA, ENNA1, ENNB, ENNB1). The extraction was performed for both methods using a mixture of CH3CN/H2O/CH3COOH (79/20/1, v/v/v), while the dilution/purification was carried out through two different procedures: (1) by the “dilute-and-shoot” technique diluting 1:2 the filtered extract with CH3CN/H2O/CH3COOH (20/79/1, v/v/v) to reduce the matrix effect; (2) using the Oasis® PRiME HLB clean-up columns. The analysis was carried out using CH3OH and H2O both acidified with 0.1% of CH3COOH as eluents. The injection volume was 20 μL and the flow rate 200 μL min-1. The analysis of two reference material (maize and wheat), was performed to evaluate the trueness and precision of the two methods by matrix-matched calibration curves. For all the regulated mycotoxins analyzed by both methods, the range of recovery percentage established by the Regulation (EC) No. 401/2006 was respected, except for ZEA by using the Oasis® PRiME HLB clean-up columns. Nevertheless, the results suggest that the Oasis® PRiME HLB clean-up columns, could be a valid alternative to the dilute-and-shoot method, although an additional cost for the clean-up has to be considered. In conclusion, both two analytical methods considerably reduce the analytical time and costs and therefore result to be promising and applicable for high-throughput routine multi-mycotoxins analysis by the use of a TQ

Grain yield enhancement through fungicide application on maize hybrids with different susceptibility to northern corn leaf blight

Foliar fungicides are widely used to control pests on several crops and, from mid-2000s, have become more common on maize. The yield advantages derived from foliar fungicides on maize, as for other crops, could be related not only to the direct control of the disease, but also to physiological effects on the plant. The aim of the research was to evaluate the response of maize to the application of an azoxystrobin and propiconazole mixture. The fungicide was applied to hybrids with different susceptibility to northern corn leaf blight (NCLB) foliar disease at the beginning of stem elongation or at the tassel emergence stage. The best application timing resulted to be at the tassel emergence stage for both pathogen control and grain yield. The treatment effectively controlled disease development on the two hybrids susceptible to NCLB. However, the yield of the moderately-resistant hybrid increased unexpectedly to a comparable extent, even though no significant fungal containment was detected from a visual inspection. The peroxidase and superoxide dismutase activity, the protein leaf content and the translocation efficiency of carbohydrates from the leaf to the ear were not influenced by the fungicide treatments, differently from what had been previously shown on wheat. The authors suggest that rather than the improved metabolism of the reactive oxygen species, the positive effect of the fungicide on the moderately-resistant hybrid is due to other physiological mechanisms. It is hypothesized that the fungicide leads to better yields as it prevents the allocation of metabolic resources to actively defend against the pathogen