A study of the stability of nicotine and cotinine in unfrozen plasma was carried out in order to find out whether measurements from unfrozen samples posted to the laboratory are reliable. Plasma left at room temperature for 12 days had nicotine and cotinine concentrations which correlated highly (r > 0.99) with those in duplicate samples frozen immediately. There was no evidence of a shift in values or an increase in variability due to delayed freezing for either nicotine or cotinine. These results suggest that unfrozen plasma samples posted to the laboratory provide nicotine and cotinine measurements which are acceptably reliable for both clinical and research purposes.
|Original language||English (US)|
|Number of pages||4|
|Journal||Journal of Smoking-Related Disorders|
|State||Published - 1994|
All Science Journal Classification (ASJC) codes