Cotinine detection and tobacco smoke exposure

Tobacco is one of the major preventable causes of morbidity and premature mortality in the world. A simple, rapid method for determination of cotinine, major metabolite of nicotine in urine, is described. The a,,;say involves a fast liquid-liquid extraction with chloroform as a solvent in alkaline environment. The extract was dried at 37 degrees C and the residue was dissolved in 100 mu L of standard internal of pyridine in methanol solution, and an aliquot was analyzed by gas-liquid chromatograph equipped with a flame -ionization detector. This technique was performed to test urine of a sample of smokers and non-smokers who were previously asked about their smoking habit. The limit of detection was 3.1 ng/mL, and using two calibration curves, a linearity range from 3 a 5.000 ng/mL was covered. The median and quartiles (Q) of cotinine in smokers were 255.4 ng/mL, 15.9 ng/mL (Q1) 1050.2 ng/mL Q3) ng/mL and in non-smokers 15.8 ng/mL, 4.1 ng/mL (Q1) - 38.4 ng/mL (0). Wilcoxon sumrank: z = 4.865 p < 0.01. There was a relationship between cotinine concentration in urine and number of smoked cigarettes. Spearman's rho = 0.5672 (p < 0.001), This technique could identify smokers, second hand smokers and non-smokers using cut-off of 10-15 ng/mL of cotinine in urine, usually adopted in epidemiological studies.