Establishment of high‐performance liquid chromatography‐photodiode array method for 43 weight loss agents and effect of basic environment on bisacodyl degradation

Rationale The demand for weight loss products is increasing as slimness emerges as the new aesthetic standard and people's desire to achieve it increases. In addition, the distribution and sale of products containing illegal ingredients, pharmaceuticals, and chemicals for which safety is not guaranteed and that cannot be used as foods or dietary supplements are increasing. Thus, the development of an analytical method that could monitor these illegal products is required. Methods A high‐performance liquid chromatography‐photodiode array method capable of rapid and reliable qualitative and quantitative analyses of 43 weight loss agents was established and validated. Results The process involved dividing analytes into three groups for rapid analysis; when bisacodyl was mixed with chlorocyclopentylsibutramine, it decomposed into its metabolites: monoacetyl bisacodyl and bis‐(p‐hydroxypheny)‐pyridyl‐2‐methane. This decomposition was due to NaOH that was used to prepare the chlorocyclopentylsibutramine standard solution. Bisacodyl did not degrade when mixed with neutralized chlorocyclopentylsibutramine, whereas when NaOH was added, it rapidly degraded. We identified the bisacodyl degradation products using liquid chromatography‐quadrupole‐Orbitrap/mass spectrometry. MS2 spectra with proposed structures of fragment peaks were also obtained. Conclusions The developed method could be used to regulate slimming products that threaten public health, and knowledge of bisacodyl degradation will be used as the basis for developing an analytic method.