Spectral Insights: Bathochromic Shifts in Visible Spectra of Nicotinamide with Ninhydrin

Most of the pharmaceuticals are analyzed using UV-Visible methods due to their simplicity, better understanding for students, and economy. Ammonia and primary amino groups, whenever heated with ninhydrin in the presence of ammonium molybdate, form a rhenium purple color. The simple, precise, and cost-effective UV-Visible method has been developed and validated for the determination of Nicotinamide in bulk drugs. The method is based on the reaction of ninhydrin with amide present in Nicotinamide in the presence of ammonium molybdate to form a blue chromogen, which is determined spectrophotometrically at 761nm. The effects of variables such as temperature, heating time, concentration of colour-producing reagent, and stability of colour were investigated to optimize the procedure. The method is validated for linearity, accuracy, and precision parameters. The rhenium purple color of chromogen is shifted towards longer wavelengths (from 570 nm to 761 nm). Thus, Nicotinamide shows a Bathochromic shift due to the presence of the amide group. This reaction is quantitatively proceeding at 970±1°C in 5 minutes. Beer Lambert’s law is obeyed in the concentration range of 0-125 µg/ml and is described by the regression equation y = 0.0047x with a regression coefficient (r2) of 0.9997. For Nicotinamide, the value of molar absorptivity and Sandell’s sensitivity are 2.3487 x 102 L/mol/cm and 0.2166 µg/ cm2, and LOD and LOQ are found to be 0.0238 and 0.0722 µg/ml, respectively. The statistically validated results indicate that the proposed method is simple, precise, green, and cost-effective.