The concept of Relative Absorptivity Distribution for enhancing disbanding power of spectrophotometric technique to resolve co-formulated tablets: A tool for purity index and uniformity assessment

Abstract

Resolving the spectral bands of the drugs into their discrete constituents is critical for an effective mathematical spectrophotometric method. The spectral resolution is ordinarily affected by the required application. In the current work an innovative, simple and green Relative Absorptivity Distribution (RAD) concept was established for the successful assay and assessing of content uniformity and purity index of tablet co-formulation which is recommended for lowering the blood glucose level and is comprised of Cangliflozin (CGF) and Metformin CGF and MTF. From the spectrophotometric perspective, the investigation of this combination is challenging as the composition of the tablets is CGF:MTF (1:17), where CGF is not only the minor analyte but also the one of lower absorptivity. The RAD concept is based on the production of master Resolving Spectra (RS). Within the RAD concept and according to the manipulation used for the generation of the RS, three different univariate mathematic methods via spectrophotometer software were developed. The proposed methods are characterized by the ability of extracting the raw spectra of each investigated analyte separately, consequently, enabling each analyte to be determined at its λmax without the contribution of the other. The proposed methods had analyzed CGF in the range 1.0–30.0 μg/mL and MTF within the range 1.0–20.0 μg/mL. The guidelines of the ICH were performed for the complete validation of all methods and the results confirmed satisfactory accuracy, precision and selectivity. The accomplished results together with the simplicity and low-cost of all methods suggested their suitability for the routine quality control analysis of bulk materials, assay of the pharmaceutical formulations and evaluating the content uniformity. Statistical comparison of the results with those of reported HPLC method showed good agreement. In addition, the environmental impact of the proposed methods was assessed by utilizing the National Environmental Methods Index (NEMI), the Analytical Eco-Scale and the Green Analytical Procedure Index (GAPI) where the three tools confirmed the environmentally friendly nature of all proposed methods.