Kaushik Mandal1 and Abhishek Jha

A new, simple, rapid and novel spectrophotometric method has been developed for estimation of Ramipril (RAM) and Hydrochlorothiazide (HCT) in bulk and combined pharmaceutical formulations using First order derivative method. It is a useful means of resolving the spectra and eliminating the interference. It involves conversion of normal spectrum to first and second or higher order spectra where the amplitude in the derivative spectra is proportional to the Conc. of analyte provided the Beer’s law is obeyed.The successive development of zero crossing technique was accordingly due to the feature of derivative spectra to show singles with both positive and negative value. This technique exploits the single crossing through the abscissa axis, for given components. Zero crossing technique is particularly effective in the analysis of several complex mixtures, when  peaks overlapping are present in the corresponding zero order spectra. λmax of RAM was found at 341nm and HCT at 229nm in ethanol respectively. Beer’s law obeyed in concentration range of 0.1‐ 0.5 μg/ mL for RAM and 0.25‐ 1.25 μg/ mL for HCT respectively by the method. This method was validated for precision, reproducibility, linearity and accuracy as per ICH guidelines. The proposed method is recommended for routine analysis since this is rapid, simple, accurate, cost effective , also sensitive and specific. It involves neither heating nor use of any hazardous organic solvent for separation of the combination.