Meconium Nicotine and Metabolites by Liquid Chromatography–Tandem Mass Spectrometry: Differentiation of Passive and Nonexposure and Correlation with Neonatal Outcome Measures

sensitive and objective alternative to maternal self-report for detecting prenatal tobacco exposure. Nico-tine and metabolite disposition in meconium is poorly characterized, and correlation of analytes ’ concen-trations with neonatal outcomes is unexplored. Our objectives were to quantify nicotine, cotinine, trans-3-hydroxycotinine (OH-cotinine), nornicotine, norcoti-nine, and glucuronide concentrations in meconium, identify the best biomarkers of in utero tobacco expo-sure, compare meconium concentrations of tobacco-exposed and nonexposed neonates, and investigate concentration–outcome relationships. METHODS: We quantified concentrations of nicotine and 4 metabolites with and without hydrolysis simul-taneously in meconium from tobacco-exposed and nonexposed neonates by liquid chromatography–tan-dem mass spectrometry. We compared meconium concentrations to birthweight, length, head circumfer-ence, gestational age, and 1- and 5-min Apgar scores. RESULTS: Nicotine, cotinine, and OH-cotinine were the most prevalent and abundant meconium tobacco biomarkers and were found in higher concentrations in tobacco-exposed neonates. Whereas cotinine and OH-cotinine are glucuronide bound, performing the lengthy and costly enzymatic hydrolysis identified only 1 additional positive specimen. Unconjugated nico-tine, cotinine, or OH-cotinine meconium concentra-tion 10 ng/g most accurately discriminated active from passive and nonexposed neonates. There was no significant correlation between quantitative nicotine and metabolite meconium results and neonatal out-comes, although presence of a nicotine biomarker pre-dicted decreased head circumference. CONCLUSIONS: Unconjugated nicotine, cotinine, and OH-cotinine should be analyzed in meconium to de-tect in utero tobacco exposure, as approximately 25% of positive specimens did not contain cotinine. Immu-noassay testingmonitoring cotinine onlywould under-estimate the prevalence of prenatal tobacco exposure. © 2008 American Association for Clinical Chemistry Tobacco exposure during gestation presents significant health concerns for pregnant women and fetuses. Th