This document specifies a method for the quantification of four tobacco specific nitrosamines (TSNAs) in tobacco and the following tobacco products: cigarettes, cigars and smokeless tobacco products using reversed phase high performance liquid chromatography with tandem mass spectrometry (LC-MS/MS). The TSNAs determined with this method are: N-nitrosonornicotine (NNN), N-nitrosoanatabine (NAT), N-nitrosoanabasine (NAB) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK).