Development and validation of q-absorbance ratio method for simultaneous quantification of linagliptin and metformin HCl in synthetic mixture and combined tablets

The present study aims to develop and validate simple, cost effective Q-Absorbance Ratio Method for simultaneous quantification of Linagliptin (LIN) and Metformin HCl (MET). The proposed medium Acetonitrile: Methanol: Distilled Water at 1:1:1 (Solvent Blend) identified λmax 235nm for MET, 298nm for LIN and Isobestic point at 231.7nm for Q-Absorbance Ratio Method. The validation follows ICH Q2(R1) guidelines, demonstrating excellent linearity, accuracy, precision and sensitivity (LOD and LOQ) for LIN and MET. The developed method was successfully applied to a synthetic mixture and marketed formulation, showing % recovery within the acceptable limit with % RSD was less than 2.