Eco-friendly-assessed TLC-densitometry and absorptivity coefficient based spectrophotometric methods for resolution and simultaneous analysis of two gastrointestinal acting drugs with superimposed spectra

Abstract

Three eco-friendly methods were applied and validated for simultaneous determination of two commonly prescribed drugs for gastro-intestinal treatment Ranitidine hydrochloride and Metronidazole in bulk powder and in their pharmaceutical preparations in the ratio of 3:5. The first two methods were based on smart spectra manipulating approaches to resolve the zero-order spectrum of each drug as single pure component and measuring their concentrations using the absorbance value at the corresponding λ max, 325 nm and 311 nm for Ranitidine and Metronidazole, respectively. Both methods named response correlation method and a- centering method depend on the presence of an isosbestic point between the superimposed spectra of both drugs. While the third method was a TLC-densitometric one which was performed on silica plates F254 using a mobile phase composed of methanol and ethyl acetate in a ratio (24:6 v/v). The results of the presented methods came out to be acceptable with respect to accuracy and precision and the selectivity was evaluated through analysis of synthetic mixtures of the both drugs in different ratios. All the results were validated according to the ICH guidelines. The green character of the developed methods was assessed using a new tool called Green Analytical Procedure Index (GAPI)