Discovery and Confirmation of a Novel Chlorinated Bisacodyl Derivative Illicitly Added to a Functional Fruit and Vegetable Juice Beverage

During the routine surveillance of functional beverages sold online, a fruit and vegetable juice product marketed for weight-loss and fat-burning effects was suspected of containing an illegally added non-edible substance. Non-targeted screening using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) showed that the ion fragments of the unknown compound were highly structurally related to the characteristic fragments of bisacodyl, a stimulant laxative, although the specific configuration of the suspected compound could not be immediately determined from the above results initially. To confirm its identity, the compound was independently synthesized to obtain an analytical standard. Its structure was fully elucidated using a combination of UPLC-Q-TOF/MS, high-performance liquid chromatography with diode array detection (HPLC-DAD), and nuclear magnetic resonance (NMR) spectroscopy. The synthesized compound was confirmed to be identical to the adulterant found in the beverage. The results demonstrated that this compound was a novel bisacodyl derivative — 5-Cl-bisacodyl dicyclopropyl carboxylate (5-Cl-BDC). Furthermore, a sensitive and reliable UPLC-MS/MS quantitative method was developed and validated, with a limit of quantification of 2.5 µg/kg. The method was successfully applied to determine the adulterant level (approximately 394 µg/kg) in the incriminated sample. This integrated approach, combining non-targeted screening, chemical synthesis for standard acquisition, and multi-technique confirmation, provides a robust strategy for identifying and quantifying novel, structurally modified illegal additives in complex food matrices, thereby addressing an emerging challenge in functional food safety. • A novel chlorinated bisacodyl derivative, 5-chlorobisacodyl dicyclopropyl carboxylate （5-Cl-BDC）, was first identified as an illegal adulterant in a weight-management functional beverage. • A validated UPLC-MS/MS method was developed for sensitive quantification (LOQ = 2.5 µg/kg) of the novel adulterant in complex food matrices, exhibiting superior sensitivity to previously reported methods (50–100 µg/kg). • Real-sample analysis revealed a significant adulteration level (~394 µg/kg), highlighting an emerging safety risk in weight-management functional foods. • Discrepancies in NMR assignments were observed compared with earlier reports, providing a valuable reference for the structural identification of related bisacodyl derivatives. • This study elucidates the derivatization and metabolic pathways of such compounds, along with their qualitative and quantitative ion pair information after derivatization, offering a referenceable workflow for identifying structurally modified illegal additives without commercial standards.