title: Measurement of nicotine and cotinine in human milk by high-performance liquid chromatography with ultraviolet absorbance detection.
abstract: A high-performance liquid chromatographic (HPLC) assay for the determination of nicotine and cotinine in human milk was developed using an extraction by liquid-liquid partition combined with back extraction into acid, and followed by reverse-phase chromatography with UV detection of analytes. The assay was linear up to 500 microg/l for both nicotine and cotinine. Intra- and inter-day relative standard deviations (R.S.D.) were <10% (25-500 microg/l) for both nicotine and cotinine. Limits of quantitation (LOQ) were 10 and 12 microg/l for nicotine and cotinine, respectively, while the limits of detection (LOD) were 8 and 10 microg/l for nicotine and cotinine, respectively. The mean recoveries were 79-93% (range 25-500 microg/l) for nicotine and 78-89% (range 25-500 microg/l) for cotinine. The amount of fat in the milk did not affect the recovery. We found that this method was sensitive and reliable in measuring nicotine and cotinine concentrations in milk from a nursing mother who participated in a trial of the nicotine patch for smoking cessation.
authors.affiliation: Pharmacology Unit, School of Medicine and Pharmacology, The University of Western Australia, M510, 35 Stirling Highway, Crawley 6009, Australia. msharp@receptor.pharm.uwa.edu.au
authors.forename: Madhu
authors.initials: M
authors.lastname: Page-Sharp
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Hale
authors.forename: L Peter
authors.initials: LP
authors.lastname: Hackett
authors.forename: Judith H
authors.initials: JH
authors.lastname: Kristensen
authors.forename: Kenneth F
authors.initials: KF
authors.lastname: Ilett
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003367:Cotinine / Q000032:analysis*; D006801:Humans; D008895:Milk, Human / Q000737:chemistry*; D009538:Nicotine / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012907:Smoking / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*
chemical_list: D009538:Nicotine; D003367:Cotinine