A new gas chromatography-mass spectrometry method for simultaneous determination of total and free trans-3'-hydroxycotinine and cotinine in the urine of subjects receiving transdermal nicotine

Allena J. Ji, George M. Lawson, Rodger Anderson, Lowell C. Dale, Ivana T. Croghan, Richard D. Hurt

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

trans-3'-Hydroxycotinine (THOC) has been recognized as the most abundant metabolite of nicotine. In an attempt to assess THOC and cotinine (COT) concentrations during nicotine transdermal therapy, we developed a new quantitative gas chromatography-mass spectrometry (GC-MS) method for simultaneous determination of total and free THOC and COT in human urine. The method utilizes the following: (a) hydrolysis of conjugated THOC and COT by β-glucuronidase; (b) basic extraction of THOC and COT with mixed dichloromethane and n-butyl acetate; (c) derivatization of THOC with bis(trimethylflurosilyl)acetamide; and (d) separation and identification by GC-MS with selective ion monitoring. Lower limits of quantification for the assay were 50 and 20 μg/L for THOC and COT, respectively. The intra- and interassay CVs were 4.4% and 11% for THOC, and 3.9% and 10% for COT at 1000 μg/L. The results from six consecutive 24-h urine collections in 71 subjects administered daily transdermal nicotine doses of 11, 22, and 44 mg showed that, on average, free THOC was 76% of total THOC and free COT was 48% of total COT in all subjects. THOC is the major metabolite of nicotine and constitutes 20% of total nicotine intake at steady state, whereas urinary nicotine and COT excretion were 8% and 17%, respectively. The method is useful for simultaneous determination of free and total THOC and COT and can be used to assess the urinary excretion of these metabolites during transdermal nicotine therapy.

Original languageEnglish (US)
Pages (from-to)85-91
Number of pages7
JournalClinical chemistry
Volume45
Issue number1
StatePublished - Jan 23 1999

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Biochemistry, medical

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