Simultaneous determination of nicotine and eight nicotine metabolites in urine of smokers using liquid chromatography-tandem mass spectrometry.

A method based on liquid chromatography tandem mass spectrometry (LC-MSMS) applying atmospheric pressure chemical ionisation (APCI) in the positive ion mode was developed for the direct determination of nicotine, cotinine, trans-3'-hydroxycotinine, their corresponding glucuronide conjugates as well as cotinine-N-oxide, norcotinine, and nicotine-N'-oxide in the urine of smokers. The assay involves filtration of crude urine, fast liquid chromatography on a reversed-phase column and mass-specific detection using MSMS transitions. Deuterium-labeled nicotine, cotinine, and trans-3'-hydroxycotinine were used as internal standards. Glucuronides used as reference material were either chemically (cotinine-N-glucuronide) or enzymatically synthesized (nicotine-N-glucuronide and trans-3'-hydroxycotinine-O-glucuronide). Precision for the major nicotine analytes at levels observable in urine of smokers was better than 10%. Accuracy expressed in recovery rates in urine matrix for nicotine, cotinine, trans-3'-hydroxycotinine, and cotinine-N-glucuronide ranged from 87 to 113%. Quantitative results for the three glucuronides in urine samples of 15 smokers were compared to an indirect method in which the aglycons were determined with gas chromatography and nitrogen-selective detection (GC-NPD) before and after enzymatic splitting of the conjugates. Good agreement was found for cotinine-N-glucuronide (coefficient of variation, CV: 9%) and trans-3'-hydroxycotinine-O-glucuronide (CV: 20%), whereas the accordance between both methods was moderate for nicotine-N-glucuronide (CV: 33%). The described LC-MSMS method allows the simultaneous determination of nicotine and eight of its major metabolites in urine of smokers with good precision and accuracy. Since the method requires a minimum of sample clean-up and a very short time for chromatography (3 min), it is suitable for determining the nicotine dose in large-scale human biomonitoring studies.

Determinants of children's exposure to environmental tobacco smoke (ETS): a study in Southern Germany.

Maternal smoking has been repeatedly found to be the most important determinant of children's exposure to environmental tobacco smoke (ETS). Here, we further investigated predictors for the urinary cotinine/creatinine ratio (CCR, ng/mg) in 1220 preschool children for the year 1996. Children from smoking homes (35.1%) had significantly higher CCR than children from nonsmoking homes (mean: 55.5 vs. 14.9 ng/mg). The level of education of the parents was a strong predictor for CCRs even after adjusting for number of cigarettes smoked, maternal smoking and dwelling space. Additionally, dwelling space was inversely related to children's urinary cotinine level. The CCR- levels in children investigated in 1996 and 1998 were significantly correlated (Pearson's r=0.67). The parents of 806 children agreed for a visit to their homes. In 79 of the 536 (14.7%) of the self-reported, nonsmoking households, smoking was admitted during the visit. The mean urinary CCR of these children was 25.2 ng/mg. We conclude that in addition to parental smoking behaviour, other variables such as dwelling space and social and educational status predict the children's exposure to ETS. Our data also revealed that a considerable percentage of parents denied the ETS exposure of their children at home.