Comprehensive overview of the analytical methods for determining pyrrolizidine alkaloids and their derived oxides in foods

Abstract

Pyrrolizidine alkaloids and their derived oxides are toxins naturally produced by plants when they are exposed to stress factors. In particular, the unsaturated pyrrolizidine alkaloids exhibiting a double bond between the 1,2-positions have caused great interest in recent years since they have pneumotoxic, genotoxic and carcinogenic effects upon ingestion. In this review, focus on their chemical structure justifying their toxicity is provided as well as insight on the recently adopted EU regulatory framework. In addition, to reveal current trends and highlight the research effort in the field, an all-time bibliometric analysis was performed for the first time. It was found that tea, infusions, honey, spices, and cereals are the most common foodstuffs in which pyrrolizidine alkaloids have been detected. In terms of pre-analytical steps, the application of efficient sample preparation is necessary to detect pyrrolizidine alkaloids in complex food matrices. Solvent extraction followed by a clean-up stage, e.g., solid-phase extraction was the most applied option. Focusing on the analytical methods, liquid chromatography combined with various mass spectrometry detectors has been the golden standard in the field. Gas chromatography methods were also applied, but the need for analyte derivatisation has hindered their application. All in all, this review provides an overview on the analysis of pyrrolizidine alkaloids and their derived oxides, comprehensively discussing the up-to-date advances and highlighting the analytical challenges to be faced.