Development and validation of UV spectrophotometric methods for the simultaneous estimation of dexamethasone and neomycin sulphate in bulk drug and pharmaceutical formulations
Keywords:Dexamethasone, Neomycin Sulphate, Third order derivative method and Absorbance Ratio method.
In the present work two simple, precise, accurate and economical spectrophotometric methods have been developed for the simultaneous estimation of Dexamethasone and Neomycin Sulphate in bulk drug and pharmaceutical dosage forms by using distilled ethanol as a solvent. Method A is a Third order derivative method, which involves the measurement of absorbance of one drug at zero crossing point of other; hence wavelengths 230 nm and 262 nm were selected for the estimation of Dexamethasone and Neomycin Sulphate respectively. Method B is a Q-Absorbance ratio method, which is based on the measurement of absorbances at two selected wavelengths 216nm (Iso-absorptive point) and 258nm for the estimation of Dexamethasone and Neomycin Sulphate respectively. Beer’s law was obeyed in the concentration range of 1-80µg/mL for Dexamethasone and 5-100 µg/mL for Neomycin sulphate. Working concentrations used in the range of 2-10 µg/mL and 10-50 µg/mL for Dexamethasone and Neomycin Sulphate respectively. The% RSD for intra-day and inter-day precision was within 2% for both the methods.