Utilization of 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) for kinetic spectrophotometric assay of befunolol hydrochloride in its pharmaceutical formulation.

A simple, accurate, precise, and sensitive kinetic spectrophotometric method for determination of befunolol hydrochloride is described. The method is based on the formation of a colored product with 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) in methanol at 70 degrees C for 45 min. The red-colored product was measured at 523 nm. The optimization of various experimental conditions is described; Beer's law was obeyed in the range 15.25 x 10(-6) to 122.04 x 10(-6) M. The results obtained showed good recoveries (100.1 +/- 0.80%). Application of the proposed method to a pharmaceutical formulation was successfully achieved. The determination of befunolol hydrochloride by fixed time, fixed concentration, and rate constant methods was feasible with the calibration equation obtained. However, the fixed time method proved to be more applicable.