Bongkrekic Acid and Its Novel Isomers: Separation, Identification, and Determination in Food Matrices

The toxicity associated with bongkrekic acid (BKA) is severe due to its chemical structure, which also facilitates high mortality rates; however, its isomer, isobongkrekic acid (iBKA), with only minor structural variance, demonstrates marked differences in toxicity. This discrepancy in structural properties and toxicity highlights that risks have been potentially underestimated within current detection standards for BKAs. In this study, a novel BKA trans isomer at the C8 and C9 double carbon bonds (E-configuration), termed iBKA-neo, was successfully separated and identified. Subsequently, the multiple reaction monitoring parameters and chromatographic conditions for three BKA isomers were optimized, enabling effective separation within 15 min via UHPLC-MS/MS, among which the ammonium positive adduct ions yielded significantly higher response intensities for all BKA isomers than traditional deprotonated molecules. Additionally, distinct differences in the ion ratios between iBKA-neo and BKA were utilized for preliminary screening. On this basis, the extraction and enrichment strategies for BKAs were optimized in food matrices and validated comprehensively with good linearity (0.25-500 μg/kg), a superior limit of quantification (0.25 μg/kg), acceptable recoveries (82.32-114.84%), and stable intraday and interday precision (an RSD less than 12.67%). These findings significantly contribute to ecotoxicology and the formulation of safety standards concerning BKAs.