QuEChERS - UHPLC-ToF-MS Method for Regulated and Emerging Mycotoxins Including Ergot Alkaloids in Rice.

Abstract

Background: Rice is susceptible to contamination by mycotoxins and ergot alkaloids, posing significant risks to food safety. Despite growing evidence of their co-occurrence, few methods allow simultaneous determination of regulated, emerging, and ergot alkaloids in rice.

Objective: A screening method based on QuEChERS method coupled with UHPLC-ToF-MS was develop and validated for the simultaneous determination of 11 mycotoxins and 12 ergot alkaloids in rice.

Methods: Chromatographic parameters, including column selection, gradient program, flow rate, and injection volume, were optimized to ensure adequate separation and sensitivity. Two extraction approaches, solid-liquid extraction (SLE) and QuEChERS, were systematically compared, and key parameters such as extraction solvent, extraction time, and salt composition were optimized to maximize recoveries across chemically diverse analytes. The validated method was applied to 41 commercially available rice samples from the Portuguese market.

Results: The validated method showed recoveries between 71-119%, repeatability (RSDr ≤ 20%), inter-day precision (RSDR ≤ 25%), and limits of quantification compliant with EU performance criteria. Aflatoxin G2 and sterigmatocystin were the most frequently detected mycotoxins, with three samples exceeding the legal limit for total aflatoxins (4 µg/kg). Mycophenolic acid was also detected in two samples.

Conclusion: The developed method demonstrated adequate sensitivity, selectivity, and precision for multi-mycotoxin surveillance, highlighting the relevance of monitoring emerging mycotoxins in rice.

Highlights: QuEChERS combined with UHPLC-ToF-MS enables simultaneous screening of 23 analytes, including ergot alkaloids, regulated myxotoxins and emerging mycotoxins. The method was validated according to Regulation (EU) 2023/2782. Aflatoxin G2 and sterigmatocystin were detected in Portuguese market rice. Mycophenolic acid was detected as an emerging contaminant.