Tobacoo-specific　nitrosamine　4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone　(NNK)　is　a　potent　carcinogen　present　in　tobacco　products　and　tobacco　smoke.　The　carcinogenic　mechanism　of　NNK　is　involved　in　the　DNA　damage　induced　by　the　active　electrophiles　generated　from　the　metabolic　activation　of　NNK　catalyzed　by　cytochrome　P450.　It　is　significant　to　establish　an　in　vitro　metabolism　model　of　NNK　and　the　quantitation　method　for　the　investigation　of　tabacco　carcinogens　motabolites.　In　this　work,　the　NNK　metabolite　of　4-hydroxy-1-(3-pyridyl)-1-butanone　(HPB)　was　quantitatively　analyzed　by　high　performance　liquid　chromatography-atmospheric　pressure　chemical　ionization　tandem　mass　spectrometry　(HPLC-APCI-MS/MS).　Selective　reaction　monitoring　(SRM)　was　employed　for　determining　HPB　and　the　internal　standard　HPB　simultaneously.　The　method　shows　good　linearity　within　0.2-400　nmol/L　with　the　correlation　coefficient　(R2)　0.9999.　The　limit　of　detection　(LOD)　and　the　limit　of　quantitation　(LOQ)　are　0.025　nmol/L　(S/N=3)　and　0.05　nmol/L　(S/N=10),　respectively.　The　inter-day　and　intra-day　accuracy　range　from　96.6%　to　101.8%,　and　the　recovery　is　98.1%-102.6%.　The　in　vitro　metabolism　model　of　NNK　can　be　used　to　elucidate　the　molecular　mechanism　of　the　metabolic　activation　of　tobacco-specific　nitrosamine.　This　work　layed　a　foundation　for　the　quantification　of　biomarkers　for　tobacco　carcinogenesis.　©,　2014,　Journal　of　Chinese　Mass　Spectrometry　Society.　All　right　reserved.