Determination of nicotine and its major metabolite cotinine in plasma or serum by gas chromatography-mass spectrometry using ion-trap detection

A specific method has been developed for the quantitative determination of nicotine and its major metabolite cotinine in plasma or serum of active and passive smokers. Deuteriumlabelled nicotine and cotinine were used as internal standards. The amounts of nicotine and cotinine present in a sample of plasma or serum were extracted with a simple extraction procedure (liquidliquid or solidphase extraction). The extracts were analysed by gas chromatography coupled with mass spectrometry using iontrap detection. The analysis was done in positive chemical ionisation with methanol as the liquid reagent. The method has been demonstrated to be linear up to 1000 g/l. Limits of quantification for nicotine and cotinine are 10 and 5 g/l, respectively with liquidliquid extraction, and 1 g/l for each of the compounds with solidphase extraction. The present method has been applied to several real cases.