High performance liquid chromatographic determination of nicotine and cotinine in plasma and nicotine and cotinine, simultaneously, in urine.

Three analytical procedures were developed to determine nicotine in plasma, cotinine in plasma and, simultaneously, nicotine and cotinine in urine. After liquid or solid-phase extraction, the purified aqueous phase is injected into a high performance liquid chromatograph equipped with an ultra-violet detector using a CN Spheri-5 micron cartridge-column with an inner diameter of 4.6 mm and a length of 10 or 22 cm. The limit of quantitation for nicotine in plasma was around 8 to 15 ng/ml, that of cotinine in plasma around 50 ng/ml and that of nicotine and cotinine in urine around 170 ng/ml and 70 ng/ml, respectively. The limit of detection of nicotine in plasma was around 1 ng/ml and that of nicotine and cotinine in urine around 20 ng/ml and 10 ng/ml, respectively. The passive exposure to cigarette smoke by non-smokers and the "resting levels" of nicotine in plasma and urine of smokers were studied. The analytical methods were set up to study the pharmacokinetics and bioavailability of nicotine in healthy volunteers following single and repeated administrations of different doses of transdermal nicotine systems.