This International Standard specifies the procedure for the determination of the tobacco specific nitrosamines(TSNAs): N-nitrosonornicotine (NNN), N-nitrosoanatabine (NAT), N-nitrosoanabasine (NAB) and4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in ground leaf tobacco, manufactured tobacco andtobacco products by gas chromatography.