SIMPLE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC METHOD TO VERIFY THE DIRECT BARBITURIC-ACID ASSAY FOR URINARY COTININE

An isocratic HPLC method is described to determine urinary concentrati ons of nicotine and cotinine after derivatization with cyanogen chlori de and barbituric acid. This method has been used to assess the reliab ility of the direct barbituric acid assay to determine smoking status. It is concluded that the direct barbituric acid assay is a very relia ble indicator of smoking status, provided that urine blank samples are prepared to correct for background absorbance. If the direct barbitur ic acid assay is in disagreement with self-reported smoking status, th is HPLC procedure is a useful method to resolve the discrepancy.