Mass Spectrometric Quantitation of Nicotine, Cotinine, and 4-(Methylnitrosamino)-1-(3-Pyridyl)-1-Butanol in Human Toenails

Abstract

Numerous studies have quantified total cotinine (the sum of cotinine and cotinine-N-glucuronide) and total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol [NNAL; the sum of NNAL and its O-and N-glucuronides (NNAL-Glucs)] in the urine and blood of smokers, smokeless tobacco users, and nonsmokers exposed to environmental tobacco smoke. Analysis of hair and nails has several advantages over blood and urine testing, such as accumulation of xenobiotics during long-term exposure, ease of collection, and indefinite stability of samples. We developed sensitive methods for quantitation of nicotine, cotinine, and NNAL in human toenails. Nicotine and cotinine were analyzed by gas chromatography-mass spectrometry-selected ion monitoring. NNAL was assayed using liquid chromatographyelectrospray ionization-tandem mass spectrometry-selected reaction monitoring. The detection limits of the methods were 0.01 ng/mg toenail for nicotine, 0.012 ng/mg toenail for cotinine, and 0.02 pg/mg toenail for NNAL. In 35 smokers, the mean nicotine level was 5.9 F 5.6 ng/mg toenail, mean cotinine was 1.6 F 1.3 ng/mg toenail, and mean NNAL was 0.41 F 0.67 pg/mg toenail. Samples collected from six nonsmokers were negative for NNAL. In smokers, NNAL correlated with cotinine (r = 0.77; P < 0.0001). The results of this study for the first time show the presence of cotinine and NNAL in human toenails. These sensitive and quantitative methods should be useful in epidemiologic studies of the role of chronic tobacco smoke exposure, including environmental tobacco smoke exposure, in human cancer. (Cancer Epidemiol Biomarkers Prev 2006; 15(12):2378 -83)

Relationship of Human Toenail Nicotine, Cotinine, and 4-(Methylnitrosamino)-1-(3-Pyridyl)-1-Butanol to Levels of These Biomarkers in Plasma and Urine

“…The overall mean values and the ranges of toenail biomarker levels observed here are in good agreement with those obtained in our previous study (27). The correlation of toenail NNAL with toenail cotinine observed in this study (r = 0.69) was also similar to that reported previously (r = 0.77; ref.…”

“…Because the analysis involves NaOH digestion, N-glucuronides of these compounds would be converted to their aglycones. Further experiments with h-glucuronidase indicated that NNAL-O-Gluc was not present in human toenails (27). Therefore, the values reported in this article are total nicotine, cotinine, and NNAL, but it is likely that these analytes in toenails are mainly in their nonconjugated form.…”

“…Nicotine, cotinine, and NNAL in toenail clippings were analyzed as described previously (27). Because the analysis involves NaOH digestion, N-glucuronides of these compounds would be converted to their aglycones.…”

“…Recently, we developed sensitive and quantitative methods for analysis of nicotine, cotinine, and NNAL in human toenails (27). Measurement of toenail biomarkers has certain advantages, including ease of collection and storage and potential evaluation of cumulative exposure over a relatively long period due to the slow (f0.1 cm/mo) growth of toenails (28).…”

Current research on cigarette toxicity: critical appraisal in view of clinical laboratory

“…[80][81][82] The distinctions of these techniques over self-reports are centred on issues with validity, reliability and misclassifications. 80 In this appraisal, we would analyse the study of Al-Delaimy WK et al, which compared toenail nicotine biomarkers and self-reports in view of clinical laboratory practice.…”