Abstract: A rapid method for the determination of the contraindicated component urocanic acid(URA), approved sunscreens 2-ethylhexyl 4-methoxycinnamate(EHMC) and butyl-methoxydibenzoylmethane(B-MDM) in cosmetics were developed using direct analysis in real time (DART) of ion sources combined with four-pole flight mass spectroscopy. For qualitative analysis by positive ions, the Full MS/Targeted MS² mode is applied to obtain the mass spectrum and cosmetics can be directly analyzed in the ionized area. For quantitative analysis, DART parameters are systematically optimized to achieve the best detection performance and the module sampler is used for automatic sampling. The linear range of three kinds of components is 25~1000 mg/L in the calibration curve with a good linear relationship (r＞0.99). The lowest limit of detection (S/N=3) is 7.5 mg/L and the minimum quantitative limit (S/N=10) is 25 mg/L. The method recovery is 96.7%～109.2% and the precision RSD (n=6) is 3.59%～11.23%. The method is simple, rapid, efficient and environmentally-friend. It can be widely used in the rapid screening and quantitative detection of banned additives in cosmetics.

Key words: direct analysis in real time mass spectrometry, sunscreens, urocanic acid, 2-ethylhexyl 4-methoxycinnamate, butyl-methoxydibenzoylmethane