Spectrofluorimetric determination of fenoterol in pharmaceuticals

A highly sensitive spectrofluorimetric method was developed for the determination of fenoterol HBr in pharmaceutical preparations. The method is based on the nitrosation of fenoterol followed by reaction with 2-cyanoacetamide in the presence of ammonia and measuring the produced fluorescence at 380 nm after excitation at 338 nm. All the variables affecting the reaction conditions were carefully studied and optimized. Linear calibration graph was obtained in the range of 0.064-0.64 mu g.mL(-1) with a correlation coefficient of 0.9999 and a relative standard deviation of 0.83%. The method was applied to dosage forms and the results obtained agreed well with those obtained by the official method. A proposal of the reaction pathway was suggested.