An analytical method based on on-line solid phase extraction(SPE) coupled with liquid chromatography-tandem mass spectrometry for determination of aniline and benzidine in underground water was developed.Sample was SPE concentrated by a HLB cartridge and separated on a HSS T3 column with a gradient mobile phase of acetonitrile and aqueous 0.1% formic acid,then analyzed by the tandem mass spectrometry.Quantification was performed by external standard calibration.When the sample injection volume was 5mL,the l...