Kinetic determination of nortriptyline in pharmaceutical samples by use of photometric and fluorimetric detection.

A fast kinetic method is proposed for the photometric and fluorimetric determination of nortriptyline hydrochloride. The method involves measuring the rate of formation of an adduct with 4-chloro-7-nitrobenzofurazan, which exhibits light absorption and fluorescent properties, and the use of a stopped-flow mixing technique, which facilitates application to automatic routine analyses. The reaction rate is measured within only 30 s. The detection limit is 0.12 micrograms ml-1 (photometry) and 0.18 micrograms ml-1 (fluorimetry) and the calibration graph is linear up to 60 micrograms ml-1 in both cases. The precision (as RSD) is less than 1.5%. The proposed method was satisfactorily used for direct analysis of pharmaceutical preparations and a mean recovery near 100% was obtained with both photometric and fluorimetric detection.