Investigation of the relationship between nicotine and cotinine concentrations in human biological samples by a GC-MS method

Abstract

In this study, a gas chromatography-mass spectrometry method was developed for the determination of nicotine and cotinine wherein human plasma, urine, and saliva. In addition, it was aimed to determine statistically the correlation between nicotine and cotinine levels in urine and saliva samples and nicotine and cotinine levels in blood samples. The limit of quantification was ≤0.83 ng/mL and precision were ≤4.91 and accuracy (RE%) was between (-4.93) and 4.90. Recovery was detected between 95.4% and 104.7%. The method was employed to determining the nicotine and cotinine concentrations in plasma, saliva, and urine total of 91 samples belong to non-smokers (n=37) and active smokers (n=54) who were healthy (n=65) and COPD patients (n=27) and the statistical relationship within the nicotine and cotinine values of the samples were investigated. It was found a correlation (r=0.752, p≤0.01) between plasma and saliva cotinine levels and estimation equation calculated as y=1.56x+43.24. Also, the correlation between plasma and urine cotinine levels was found (r=0.787, p≤0.01) by the equation that y=0.31x+34.59. The results show that by accurately determining the amount of cotinine in both saliva and urine, the exposure risks of both active smokers and those exposed to cigarette smoke with the ETS can be estimated.