Green chromatographic methods for simultaneous micro-determination of empagliflozin, linagliptin with metformin and its pharmacopoeial impurities in pure form and triple combination tablets: A comparative study

Abstract

Green analytical chemistry (GAC) is gaining great interest with the respect of global environmental pollution control (EPC). Consequently, we have developed two green chromatographic methods for the simultaneous precise and selective estimation of empagliflozin (EMP), linagliptin (LNA) with Metformin (MET) and its pharmacopoeial impurities cyanoguanidine (CGN) and melamine (MLN). The scientific database lacks any analytical reports tackling such concurrent estimation of the five cited analytes. The first developed method is a reversed phase HPLC-DAD employing Agilent C18 column (4.6 × 250 mm, 5 μm p.s.) and a mobile phase composed of methanol and 0.01 M sodium dihydrogen orthophosphate buffer of pH 2.55 (adjusted with orthophosphoric acid) eluted in a gradient mode with detection at 218 and 224 nm.The second method is HPTLC using Merk TLC plates precoated with 60 F 254 silica gel on aluminium sheet as the stationary phase developed with ethanol: ethylacetate: water (3.5: 3:1, v/v/v, respectively) as mobile phase and scanned at 216 and 224 nm. The proposed methods offered neat separation and quantitation of the five analytes in their pure form and in the triple combination tablets. Both methods were validated as per the ICH guidelines in terms of linearity, range, accuracy, precision, specificity and robustness. Moreover, Greenness assessment of the developed methods was carried out using the Analytical Eco-Scale. Further evaluation of the methods’ ecofriendliness and comparison with previously reported methods was performed using NEMI, GAPI and the novel AGREE tool.