Characterization and determination of benvitimod, an unknown risk substance in cosmetics, using nuclear magnetic resonance spectroscopy and HPLC-MS/MS.

Ultrahigh-performance liquid chromatography-tandem high-resolution mass spectrometry, combined with preparative chromatography and nuclear magnetic resonance spectroscopy, a new method for identifying unknown risk substance structures in cosmetics has been established. Moreover, HPLC-MS/MS was developed for the determination of benvitimod in cosmetics. The sample was collected in ultrahigh-performance liquid chromatography-tandem high-resolution mass spectrometry, and the molecular formula of the unknown was obtained as C17 H18 O2 . After preparative chromatography enrichment and purification, the enriched compound was scanned by nuclear magnetic resonance spectroscopy, and the chemical structure of the unknown compound was confirmed to be benvitimod. Subsequently, the separation was determined in multiple reaction monitoring mode. The results showed that the linearity of benvitimod was good in the range of 1-100 µg/L with a correlation coefficient r2  > 0.999; the limits of detection and quantification were 0.02 mg/kg and 0.067 mg/kg; the precision and stability were good; and the average recoveries were 104.2%, 108.2%, and 108.7% for low, medium, and high spiked concentrations, respectively. Forty batches of cosmetics were screened, of which two batches were detected with the illegal addition of benvitimod at 2.48 and 3.13 g/kg. The method effectively solved the loopholes in regulation and provided a research basis for the qualitative identification of structurally unknown compounds in cosmetics.