Measurement of cotinine in urine by liquid chromatography tandem mass spectrometry.
BACKGROUND
Cotinine is the major metabolite of nicotine. It is also a specific biomarker for nicotine exposure in cigarette smokers. The measurement of urine cotinine concentration will enable: (1) the assessment of the smoking status of lung transplant patients and (2) tobacco abstinence to be studied in patients during treatment under smoking cessation programmes.


METHODS
We have developed and validated a method for the measurement of urinary cotinine using reversed phase high-performance liquid chromatography (HPLC) coupled to tandem mass spectrometry (LC-MS/MS). This technique utilizes online ion exchange coupled with an analytical column to eliminate ion suppression effects. The chromatography was performed using a Waters 2795 Alliance HT LC system.


RESULTS
Cotinine and d3-cotinine had a retention time of 2.5 min and the cycle time from injection to injection was 4 min. The transition identified for cotinine was m/z 177.1>79.6 and for d3-cotinine m/z 180.2>79.6. This method was linear up to 1000 microg/L. Mean recovery of the assay was 112% with a range of 107-117% (n=9). The limit of quantitation for this assay was 2.5 microg/L and the limit of detection was 0.156 microg/L. The intra- and inter-assay imprecision was <12% and <10% respectively over a concentration range of 22-660 microg/L.


CONCLUSIONS
We have developed a robust and rapid assay for measuring and analysing urine cotinine by LC-MS/MS, by utilizing a technique, which has reduced ion suppression effects. Ultimately, the method will facilitate the assessment of lung transplant patients' smoking status.
Chadwick
Carrie Ann
CA
Department of Clinical Chemistry, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, UK. carieannchadwick@yahoo.co.uk
Keevil
Brian
B
D015415:Biomarkers / Q000652:urine; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D003367:Cotinine / Q000652:urine*; D006801:Humans; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012907:Smoking / Q000652:urine*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation / Q000379:methods; D015813:Substance Abuse Detection / Q000295:instrumentation / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000295:instrumentation / Q000379:methods
D015415:Biomarkers; D003367:Cotinine