Abstract: A method for determining the α-carboline heterocyclic aromatic amines(HAAs) in human urine by tandem solvent-solid phase extraction and HPLC-MS/MS was developed and applied in the detection of 2-amino-9H-pyrido2,3-bindole(A α C) and 2-amino-3-methyl-9H-pyrido2,3-bindole(MeAαC) in the urine samples of 20 nonsmokers and 58 smokers.The urine samples were hydrolyzed with HCl,extracted with ethyl acetate,purified by PXC cation exchange cartridges,and determined by HPLC-MS/MS.The results showed that:1) The detection limits of AαC and MeAαC were 1.86 and 3.25 pg/mL,respectively.The recoveries ranged from 91.2% to 121.0% with the precision of 2.72%-7.84%.2) The contents of AαC detected in samples ranged from 3.11 to 101.71 pg/mL,no MeAαC was detectable.3) The AaC levels in smokers'urine were much higher than those in nonsmokers,the difference was significant in variance analysis(P<0.001).This method is suitable fo r the determination of α-carboline HAAs in human urine,and AαC can be used as a biomarker of tobacco smoke exposure.