A simple and versatile strategy for sensitive SIDA-UHPLC-MS/MS analysis of Alternaria toxins in olive oil

Alternaria toxins are naturally occurring contaminants found in natural products. Given the prevalence of Alternaria toxins and the complexity of oil-rich matrices, achieving ultra-trace analysis has become a daunting task. A new sample pretreatment technique, i.e., cold-induced liquid-liquid microextraction combined with serially-coupled-columns for SIDA-UHPLC-MS/MS, was developed and reported for the first time. Theoretical and experimental investigations on the mechanism and key parameters revealed that the proposed method achieved simultaneous purification and enrichment in one-step sample extraction with a superior limit of quantitation (0.15-1.5 μg kg^-1), without further sample manipulation, such as fat removal or solvent exchange procedures prior to LC-MS. The method was validated taking into consideration EU guidelines and showed acceptable linearity (r ≥ 0.9991), accuracy with recoveries between 75 and 114% and precision with RSD≤9.7% for all of the analytes studied. It was successfully applied to the analysis of twenty samples sourced from the Mediterranean region in order to gain first insights into Alternaria toxins contaminations in olive oils. This technical approach is well suited for large-scale studies in a high-throughput and cost-effective quality assurance laboratory environments, and it has the potential to detect ultra-trace levels of toxins in complex samples, which may lead to the development of new and sustainable sample preparation procedures.