Screening of illegally adulterated oxyphenisatin and phenolphthalein derivatives in weight-loss foods via UPLC-QTrap precursor ion scanning coupled with HRMS confirmation.

The illegal addition of chemically synthesised drugs or their derivatives into foods claiming functionality poses significant public health risks. However, detecting these compounds remains challenging due to structural ambiguity and the lack of standardised comparison substance for emerging synthetic derivatives. This study describes an integrated analytical approach combining sample preparation with ultra-high-performance liquid chromatography coupled with hybrid triple quadrupole-linear ion trap mass spectrometry (UPLC-QTrap/MS) for the screening and detection of oxyphenisatin and phenolphthalein derivatives (OAPs) in functional weight-loss foods. The addition of oxyphenisatin cyclohexanecarboxylate was confirmed in a soft candy product under the brand name "Hai Chi", although in the absence of a commercial standard, the concentration could not be established.Fragmentation patterns of specific oxyphenisatin and phenolphthalein derivatives were analysed based on collision-induced dissociation (CID) pathways in positive electrospray ionisation (ESI) mode. The method employed precursor ion-information dependent acquisition-enhanced product ion (Prec-IDA-EPI) scanning and multiple reaction monitoring (MRM) for screening and quantification. Twelve OAPs were characterised by their CID product ions, with precursor ion scanning targeting diagnostic fragments at m/z 224.1 and m/z 225.1, enabling comprehensive detection of compounds (200-800 m/z). Application of this method to 50 samples of commercial weight-loss foods led to the identification of a novel, illegally added oxyphenisatin analog in soft candy. To confirm the unknown compound, a post-hydrolysis comparison substance verification strategy was implemented, supported by high-resolution mass spectrometry (HRMS) for molecular formula confirmation.