Simultaneous Determination of Aristoloxazines, Aristolochic Acids, and Aristolactams Using HPLC–Fluorescence Detection with a Post-column Microreactor: Application in Identifying New Aristoloxazines

Aristoloxazines (AXs), aristolochic acids (AAs), and aristolactams (ALs) are potent genotoxins found in <i>Asarum</i> and <i>Aristolochia</i> plants, many of which are commonly used as herbal medicines. Emerging evidence indicates that these compounds contaminate arable soil during the cultivation of <i>Aristolochiaceae</i> herbs. Currently, no method exists for their simultaneous detection. In this study, we developed a high-performance liquid chromatography (HPLC)-based method for their determination. This method employs an iron powder-packed microreactor to convert non-fluorescent AXs and AAs into naturally fluorescent ALs, enabling fluorescence detection after HPLC separation. After being validated against LC-MS/MS analysis, the method was applied to quantify these genotoxins in herbal and soil samples, detecting AXs at concentrations as high as hundreds of μg/g in some <i>Asarum</i> samples. Given that <i>Asarum</i> plants are widely used in herbal medicine, these results reveal previously unrecognized human exposure to genotoxins that warrants the attention of both the general public and regulatory agencies.