Determination of clobetasol propionate in cosmetics by high performance liquid chromatography with pre-column fluorescence derivatization of 4-hydrazino-7-nitrobenzo [C] [1,2,5] oxadiazole

Abstract In this study, a fluorescent labeling reagent 4-hydrazino-7-nitrobenzo [c] [1,2,5] oxadiazole (NBD-NHNH2) was synthesized and used for fluorescence detection of clobetasol propionate in cosmetics by high performance liquid chromatography. In the presence of acidic catalyst (pH = 6.0), NBD-NHNH2 reacted at 45 °C for 30 min, and clobetasol propionate can be labeled quickly and efficiently. These derivatives have excellent stability and fluorescent properties. The maximum excitation wavelength was 450 nm, and the emission wavelength was 550 nm. The four cosmetic formulations were completely separated on a Waters e2695 HPLC C18 column by gradient elution. Under the optimal conditions, the standard curve showed a good linear response, and the correlation coefficient of r 2 = 0.9999. The LOD and LOQ were 0.01 ng/mL and 0.03 ng/mL, respectively. Therefore, NBD-NHNH2 was successfully applied in the detection of clobetasol propionate illegal added in cosmetics. Graphical Abstract