Abstract: Objective To explore solid phase extraction/ultra-high performance liquid chromatography-tandem mass spectrometry technique for the content determination of 5 sunscreens. Methods The samples were purified and enriched by solid phase extraction,and the 5 sunscreens in cosmetics were separated by ultra-high performance liquid chromatography,and measured by mass spectrometry with multi-reaction monitoring（MRM） mode. Results The p-benzenedimethylene-dicamphorsulfonic acid,benzimidazole sulfonate disodium and benzophenone-4 were in the range of 1 μg/L to 10 mg/L,and benzylidene-camphorsulfonic acid,phenylbenzimidazole sulfonic acid were in the range of 0.5 μg/L to 5 mg/L,there was a good linear relationship between peak area and concentration,and the correlation coefficient of regression equation（r）≥0.999 3.5 sunscreens were tested at low,medium and high concentration levels to carry out the recovery experiment. The recovery rate of 5 sunscreens was between 91.7% and 102.5%,and the relative standard deviation was between 2.6% and 4.9%. The detection limits and quantitative limits of p-benzenedimethylene-dicamphorsulfonic acid,benzimidazole sulfonate disodium and benzophenone-4 were 0.001 and 0.002 mg/kg,respectively. The detection limits of benzylidene-camphorsulfonic acid,phenylbenzimidazole sulfonic acid was 0.000 5 mg/kg,and the quantitative limits was 0.001 mg/kg. 6 batches of cosmetics samples with different types in the market were determined,and the results did not exceed the national limit. Conclusions In this method,90% acetone solution containing 2% formic acid was used as extractant,and five sunscreens in cosmetics were purified and enriched by mixed weak anion exchange column,which effectively reduced matrix interference and improved the accuracy of determination with solid phase extraction/ultra high performance liquid chromatography-tandem mass spectrometry. The actual measurement of samples showed that the method was simple,rapid,sensitive,and had wide linear range and strong anti-interference ability,and could realize the automation of sample pretreatment.

Key words: Ultra performance liquid chromatography-tandem mass spectrometry, Solid phase extraction, Cosmetics, Sunscreens