This document specifies a method for the quantification of four tobacco specific nitrosamines (TSNAs) in the total particulate matter of cigarette mainstream smoke with the intense smoking regime specified in ISO 20778 by using reversed phase high performance liquid chromatography with tandem mass spectrometry (LC-MS/MS). The quantified TSNAs are: N-nitrosonornicotine (NNN), N-nitrosoanatabine (NAT), N-nitrosoanabasine (NAB) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK).