title: Assessment of nicotine uptake from cigarette smoke: comparison of a colorimetric test strip (NicCheck I™) and gas chromatography/mass selective detector.
abstract: Colorimetric test strip assays are a convenient and inexpensive means for the determination of cotinine in human urine because they can be performed in a nonlaboratory environment using a trained technician. Four hundred human urine samples were separated into four categories: (1) heavy smokers (>20 cigarettes smoked per day), (2) light smokers (<20 cigarettes smoked per day), (3) non-smokers, and (4) vegetarian non-smokers. Samples were evaluated by a gas chromatography/mass selective detector (GC/MSD) method as a reference and using NicCheck I™ (DynaGen, Inc.). Colour intensity can range from 0 (no colour) to 14 (deep pink). Qualitative values were assigned as negative (0), low (1-6) and high (7-14). Comparison of the test strip and GC/MSD results showed: (1) 43 (10.75%) false negatives using the criterion of a GC/MSD cotinine level above 200 ng ml(-1) and test strip reading of 0, (2) 31 (7.75%) false positives using the criterion of a GC/MSD cotinine level below 1 ng ml(-1) and a test strip reading of 1 or greater, and (3) no correlation between the test strip and GC/MSD results (r = 0.597, p < 0.05). The fact that the colorimetric reaction is sensitive to many nicotine metabolites and/or heterocyclic amine structures whereas the GC/MSD method measures nicotine and cotinine selectively might explain the false positive results. False negative results were likely to be due to a lack of sensitivity of the test strip.
authors.affiliation: Department of Pharmaceutics, Virginia Commonwealth University, PO Box 980533, Richmond, VA 23298-0533, USA.
authors.forename: H
authors.initials: H
authors.lastname: Thomas Karnes
authors.forename: J R
authors.initials: JR
authors.lastname: James
authors.forename: C
authors.initials: C
authors.lastname: March
authors.forename: D E
authors.initials: DE
authors.lastname: Leyden
authors.forename: K
authors.initials: K
authors.lastname: Koller