Simultaneous determination of NNK and its seven metabolites in rabbit blood by hydrophilic interaction liquid chromatography–tandem mass spectrometry

A hydrophilic interaction liquid chromatographic–tandem mass spectrometric (HILIC–MS–MS) method for investigation of the in vivo metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a potent carcinogen, in rabbit blood has been developed and validated. This method achieved excellent repeatability and accuracy. Recovery ranged from 76.9 to 116.3 % and precision (as RSD) between 0.53 and 6.52 %. Linearity was good for all compounds (R2 > 0.9990) and the limit of detection (LOD) ranged from 0.016 to 0.082 ng mL−1. Pharmacokinetic analysis indicated that NNK was rapidly eliminated in vivo in rabbit blood and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) was the major metabolite. The hydroxy acid, keto acid, and NNAL-N-oxide were also important metabolites in rabbit blood. It is probable that α-methylene hydroxylation was the major pathway of α-hydroxylation of NNK and NNAL in the rabbit.