A simultaneous measurement of nicotine and cotinine in the urine of smokers and passive smokers by high-performance liquid chromatography

This paper describes a sensitive and reliable high-performance liquid chrom atographic method with ultraviolet detection for the simultaneous analysis of nicotine and cotinine in urine of smokers and passive smokers. The metho d involves an internal standard approach with the use of nikethamide, and c onsists of two essential steps: solid-phase extraction on Extrelut-1 column , and separation and quantitation by reversed-phase ion-pair liquid chromat ography. The calibration graphs for nicotine and cotinine were linear over the range from 20 to 2000 ng ml(-1) and from 10 to 1600 ng ml(-1), respecti vely. The relative standard deviations for above calibration ranges were fr om 6.46 to 2.09% and from 15.80 to 1.01%, respectively. The method describe d represents an improvement on different liquid chromatography procedures p reviously published and it has significant advantages mostly in terms of fi nal HPLC separation conditions.