Comparative greenness assessment for the simultaneous estimation of diclofenac and methocarbamol in their tablets applying synchronous fluorimetry

For treatment of muscle spasms associated pain, combination of nonsteroidal anti-inflammatory drugs like diclofenac (DIC) and muscle relaxants as methocarbamol (MET) is usually utilized. This work represents a novel, rapid, facile, sensitive, and selective first derivative synchronous fluorescence spectroscopy (FDSFS) for the simultaneous determination of DIC and MET in their combined tablets. Factors influencing method's sensitivity were investigated, and the best findings were accomplished applying Δ λ = 60 nm and using water as a diluting solvent. Through applying the optimized experimental conditions, DIC showed a lower detection limit of 0.15 µg/mL and a quantitation limit of 0.30 µg/mL, while MET corresponding values were 0.03 µg/mL and 0.05 µg/mL. Diclofenac was measured at 288 nm, while methocarbamol was measured at 346 nm, exhibiting linearity over the concentration ranges of 0.3-2.5 and 0.05-5.0 µg/mL, respectively. Through application to several laboratory-prepared mixtures and commercial formulation, the suggested method's applicability was determined. When comparing the proposed method to the reported HPLC method using the student's t-test and F-ratio test, no discernible differences were found. Due to simplicity and economical advantage of the method, it can be applied in quality control laboratories for analysis of the studied drugs. The evaluation of the method's eco-friendliness and greenness was also performed using Analytical GREEnness (AGREE), Green Analytical Procedure Index (GAPI) and Analytical Green Star Area (AGSA) metrics. Complete validation procedures were applied to the suggested approach in compliance with the International Conference on Harmonization's criteria.