Rapid and Simple Tandem Mass Spectrometry Method for Determination of Serum Cotinine Concentration

Abstract

Tobacco use, primarily through cigarette smoking, continues to be a primary cause of preventable death worldwide. It has been well documented that exposure to tobacco smoke, which is very common, causes chronic lung and heart disease. Data from the 1988–1991 National Health and Nutrition Examination Survey data found that 87.9% of nonsmokers had detectable concentrations of serum cotinine (1). Because of the health risks associated with tobacco exposure, analysis of biomarkers of tobacco exposure has increased. Cotinine is the preferred serum biomarker for tobacco exposure (2)(3)(4)(5). Nicotine, a natural product in tobacco, is rapidly absorbed through the lungs into the pulmonary venous circulation and then to the heart and other body organs. It has a biological half-life of only 1 h and is rapidly excreted in the urine. As such, its use to measure tobacco exposure is limited. Nicotine is metabolized primarily via oxidation of the α-carbon to cotinine and N-oxidation of the pyrrolidine ring (6)(7). Cotinine accounts for ∼90% of nicotine metabolites in serum and has a half-life of 10–40 h (8)(9). This relatively longer half-life makes it suitable for assessing exposure to cigarette smoke. Validated methods for cotinine analysis in passive smoke assessment generally require large sample volumes, which are unsuitable for pediatric populations. Available methods that use smaller sample volumes and/or less complex extractions do not provide adequate assay sensitivity, thus precluding their use in assessing passive cigarette smoke exposure (10). We describe the development of a sensitive single-step extraction and rapid method for serum cotinine based on ion spray tandem mass spectrometry (MS/MS). Cotinine was purchased from Sigma Chemical Co., d,l-cotinine-methyl-d3 from …