Quantitation of nicorandil in pharmaceutical formulations by spectrophotometry using N-(1-naphthyl) ethylenediamine dihydrochloride as coupling agent.

A validated and sensitive spectrophotometric method is developed for the quantitation of nicorandil in pharmaceutical formulations. The method is based on the reduction of nitroxy ethyl group of nicorandil to carbonyl derivative and nitrite ion by Zn/NH4Cl. The nitrite ion undergoes diazotization with sulphanilamide in presence of HCl followed by coupling with N-(1-naphthyl) ethylenediamine dihydrochloride (NED) to form a colored product with lambda(max) at 525 nm. Under the optimized experimental condition, Beer's law is obeyed in the concentration range of 0.4-12.0 microg/ml with molar absorptivity of 1.92 x 10(4) l mol(-1) cm(-1). The statistical analysis of calibration data yields the linear regression equation: A = 6.304 x 10(-4)+9.13 x 10(-2) C with correlation coefficient of 0.9999. The limits of detection and quantification are 0.05 and 0.15 microg/ml, respectively. The results obtained by the proposed method are acceptable with average recoveries of 100.0-100.1%. The results of the proposed method are compared with those of the reference method by point and interval hypothesis tests, which showed excellent agreement and there is no significant difference in accuracy and precision of methods compared.