The determination of nadolol in biological samples using high-performance liquid chromatography

A method has been developed for the determination of nadolol in biological samples by reversed-phase high-performance liquid chromatography with fluorimetric detection. The method has been applied to plasma, serum and urine samples, which are prepared by extraction with diethyl ether-dichloromethane (5:2,v/v), evaporation of the organic solvent, and dissolution of the resultant residue in the chromatographic eluent. The sample is then subjected to chromatography on a C(18)-silica column, with an eluent of water-acetonitrile-triethylamine (800:200:1,v/v) adjusted to pH 3.0 with orthophosphoric acid. A single point external standard is used for quantitation. The working ranges were 1-400 ng/ml for plasma/serum, and 0.1-40 mug/ml for urine, although a detection limit of 0.1 ng/ml appears to be readily attainable. The sample size was 0.5 ml, and for both types of sample the method showed good correlation with a previously published fluorimetric method (for plasma, r = 0.9544, n = 70; for urine, r = 0.9919, n = 35).