Abstract:

An ultra-high performance liquid chromatography-high resolution mass spectrometry （UPLC-ESI-Q-TOF/MS） method was established for simultaneous determination of meprednisone and its nine analogues in cosmetics. The samples were dispersed in saturated sodium chloride solution and extracted with acetonitrile. The separation was operated on a C₈ column using mobile phase consisting of 0.1% aqueous formic acid （A） and 0.1% formic acid-50% methanol/50% acetonitrile （B） in gradient elution. The analysis was performed using a positive electrospray ion source in full scan mode. Confirmatory analysis for target compounds was performed by comparing the retention time, parent ion and daughter ion between the suspected substance and the reference, while quantification was conducted in MS scan mode by external standard method. The results showed that the method had good linearity with the correlation coefficients above 0.99 for the ten compounds. The limits of detection were between 0.27-1.98 μg/g. The average recovery rate was in the range of 76.0%-96.4%, with RSD in the range of 1.9%-5.7%. 3 batches of positive samples were detected among 20 batches of samples, in which Clobetasol impurity B was detected in one batch, meprednisone and betamethasone EP impurity E were found in another batch, and dexamethasone was found in the third batch. This method was simple, selective and accurate, which could be used for determination of glucocorticoids in cosmetics.

Key words: ultra-high performance liquid chromatography-high resolution mass spectrometry （UPLC-ESI-Q-TOF/MS）, cosmetics, glucocorticoid