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19001717 This test is used to detect nicotine exposure by measuring nicotine and its primary metabolite, cotinine, in biological samples. Nicotine itself has a short half-life of approximately 1–2 hours, making it detectable only for a brief period after exposure. Cotinine, however, has a much longer half-life of approximately 16–20 hours, allowing detection for up to 7 days (depending on the degree of smoking), after nicotine use. For this reason, cotinine is the preferred biomarker to distinguish active smokers from non-smokers, assess recent tobacco use, and evaluate exposure to secondhand (passive) smoke.
Nicotine is a naturally occurring alkaloid found in tobacco products, including cigarettes, cigars, pipes, chewing tobacco, and other nicotine-containing products. During smoking, tobacco combustion produces thousands of chemical compounds, including nicotine, many of which are toxic. Nicotine is rapidly absorbed through the lungs and mucous membranes and reaches the brain within 10–20 seconds, where it stimulates the central nervous system and contributes to dependence and other effects.
