A method was developed for the analysis of 7 alkaloids in mainstream cigarette smoke aerosol by gas chromatography-mass spectrometry.By using electrical low-pressure impactor(ELPI),particles of cigarette smoke aerosol were divided into 12 stages and collected.The content and concentration distributions of 7 alkaloids with respect to smoke aerosol particle size were investigated.The collected aerosol particles were treated by alkali extraction method with sodium hydroxide solution and dichloromethane.The extract was separated with a DB-5MS capillary column under selected ion monitoring(SIM) mode.The targets were quantitatively analyzed using internal standard method.The results showed that,the relative standard deviations(RSDs) for the established method ranged from 2.1%to 6.4%,with limits of detection(LODs) of 0.39-14.84 ng/cig,and the recoveries at three spiked levels ranged from 85.5%to 124.8%.All of 7 alkaloids mainly distributed in aerosol of medium size particles(0.144-0.722 μm) with a peak content at particle size of 0.431 μm,which was similar to the distribution pattern of collected particle mass.The concentrations of 7 alkaloids were uniform throughout the particles of various sizes,indicating a non-specificity distribution.