Direct determination of cotinine‐ N ‐glucuronide in urine using thermospray liquid chromatography/mass spectrometry

A thermospray liquid chromatographic/mass spectrometric method has been developed for direct determination of cotinine‐ N ‐glucurinode in the urine of smokers. Quantification was performed using methyl‐ d 3 ‐cotinine‐ N ‐glucuronide as internal standard and monitoring the protonated aglycons. Using a simple preparation, urine samples from four smokers were analyzed and the results compared favorably with those from a previously reported method that quantifies aglycon release following β‐glucuronidase treatment. Amounts of cotinine‐ N ‐glucuronide found in urine from smokers ranged from less than 0.7 to 21 nmol ml −1 , indicating wide inter‐individual variability in the metabolic production of this metabolite. Cotinine‐ N ‐glucuronide was found to be the second most abundant urinary nicotine metabolite. A similar method was developed for trans ‐3′‐hydroxycotinine‐ N ‐glucuronide but this compound was not detected in smokers' urine.