Fig. 1From: Simultaneous measurement of urinary total nicotine and cotinine as biomarkers of active and passive smoking among Japanese individualsNicotine metabolites. Around 80 % of nicotine is oxidized to cotinine, mainly by cytochrome P450 2A6 (CYP 286) [19, 20]. Nicotine and cotinine glucuronides were hydrolyzed to nicotine and cotinine and measured as total nicotine and cotinine (sum of free compound and glucuronides)Back to article page