A method was established for screening and quantitative determination of cimetidine and ranitidine in cosmetics by high performance liquid chromatography-quadrupole/time of flight high resolution mass spectrometry.In addition,the tandem MS fragment pathways of cimetidine and ranitidine were studied.Samples were ultrasonically extracted with methanol and filtered,then separated on a Zorbax SB-Aq column(3.0 mm×100 mm,1.8 μm) with acetonitrile and water containing 0.1% formic acid as mobile phases by gradient elution,finally analyzed with double spray electrospray ion source in positive mode.Data were acquired in full mass scan and target mass/mass scan modes.In different cosmetic matrixes,there were good linear relationships for cimetidine and ranitidine in concentration ranges of 5.65-113 ng/mL and 4.95-99.0 ng/mL,respectively,with their correlation coefficients(r) larger than 0.999.The limits of detection for cimetidine and ranitidine were 1.1 ng/mL and 0.99 ng/mL,and the limits of quantitation were 5.6 ng/mL and 5.0 ng/mL,respectively.The recoveries of two analytes at three spiked levels varied from 86.7% to 110% with relative standard deviations(RSD) of 0.90%-6.0%,and the repeatability was satisfactory(RSD<10%).The proposed method is simple,rapid and sensitive,and could be applied in quick screening and quantitative analysis of cimetidine and ranitidine in cosmetics.