A Rapid Gas-liquid Chromatographic Method for the Determination of Cotinine and Nicotine in Biological Fluids

A rapid method is described for the simultaneous measurement of nicotine and cotinine in biological fluids using capillary column gas-liquid chromatography. Using 100 microliters sample volume the lower limit of detection for both nicotine and cotinine was 100 pg mL-1, allowing the method to be used for the measurement of these compounds in both smokers and non-smokers. The extraction time is 3 min per sample, and by using multi-pipetting and vortexing systems 250 samples can be extracted per day. The average coefficient of variation over the nicotine range 1.0 to 100 ng mL-1 was 3.9% and for cotinine over the range 1.0 to 1000 ng mL-1 was 2.2%. Saliva cotinine concentrations were quantitatively related to passive exposure to parental smoking in a population study of 1118 non-smoking schoolchildren.