Ergot Alkaloids in Rye Flour Marketed in Czech Republic: Comparison Between ELISA and LC–MS Methodologies

Ergot alkaloids (EAs) are toxins produced by Claviceps purpurea fungi that may infect cereals, particularly rye. The present study describes the comparison between ultra-high performance liquid chromatography coupled with mass spectrometry (UPLC-MS) and ELISA for the determination of twelve ergot alkaloids in rye flour. The sample preparation for LC–MS analysis was done by the QuEChERS method and clean-up via freeze-out. The analytical LC–MS method was fully validated, and the validation parameters such as linearity, limit of quantification (LOQ), precision, accuracy and matrix effect were tested. The calibration curves were linear (R² > 0.99) for all ergot alkaloids. The recoveries ranged from 74 to 104%, and the relative standard deviation under conditions repeatability (RSDr) did not exceed 17% for any analytes. The analytical LC–MS method and ELISA were applied to 27 samples of rye flour commercially available from retail shops in the Czech Republic. A positive correlation was found between the samples measured by ELISA and LC–MS. Ergot alkaloid concentrations measured by these methods were compared with the European legislation resulting in 5 samples exceeding the set limit of 500 µg/kg with 2 samples exceeding this limit 10 and 20 times, respectively. With the new legislative limit coming into effect in July 2024, more than half of the samples would not comply with the new established limit of 250 µg/kg.