Contribution of Trans 3′-Hydroxycotinine and Glucuronide Conjugates of Nicotine Metabolites to the Measurement of Cotinine by Ria

Summary

The present study was conducted to quantitate potential cross-reactivity of the cotinine radioimmunoassay (RIA) with nicotine metabolites recently quantitated in urine. Initial experiments found that about 50% of RIA reactive material could be removed by Extralut-3 chromatography which also retained a major portion of authentic trans 3′-hydroxycotinine added to non-smokers urine. This cotinine metabolite cross-reacted with 40% efficiency in the direct RIA and was measured in the urine of smokers. When samples were treated with B-glucuronidase, no differences were observed in the RIA values or in the amounts of material retained by the column. The above results account for higher cotinine values than have been observed in urine when levels are compared to gas chromatography measurements and help account for the recovery of a higher proportion of metabolized nicotine.