Saliva, plasma, urine. Gas chromatograms of nicotine and cotinine in plasma, urine, and saliva: Column: HP-FFAP, 7 m x 0.32 mm ID, 0.52 µm film; Temperature program: 70 °C, 40 °C/min to 115 °C, 1.5 min isotherm, 40 °C/min to 200 °C, 2.25 min isotherm, 40 °C/min to 210 °C, 2.75 min isotherm, Analysis time: 10 min; Carrier gas: Helium; Detector: NPD; Extraction: see protocol; Injection: 2 µl extract; Concentrations of nicotine and cotinine: in plasma 23 and 27 µg/l, in urine 73 and 100 µg/l, in saliva 115 and 130 µg/l; Peaks: 1 - Nicotine, 2 - Cotinine, 3 - 3-Methylcotinine (internal standard), 4 - Caffeine. Nicotine as a component of tobacco is not sufficient to cause acute poisoning unless tobacco is ingested by small children. However, nicotine is present in higher doses in some herbal medicines and is also used in horticulture for pest control. In the body, it is metabolized to cotinine through N-demethylation. Besides the possibility of acute nicotine poisoning, studies on smoking behavior are often the reason for determining nicotine and/or cotinine in biological samples.