Green synchronous spectrofluorimetric method for the simultaneous determination of agomelatine and venlafaxine in human plasma at part per billion levels

A novel sustainable, simple, sensitive, and green spectrofluorimetric method was developed for the concurrent estimation of venlafaxine and agomelatine in pharmaceuticals and biological fluids. The method relies on synchronous fluorescence spectroscopy, where venlafaxine and agomelatine were measured at 276 and 328 nm, respectively, using Δλ of 20 nm. The potential factors affecting the fluorescence intensity were optimized by the one-factor-at-a-time (OFAT) strategy, where synchronous fluorescence intensity was significantly enhanced using a 1% w/v sodium dodecyl sulfate micellar system. The method was fully validated and exhibited excellent linearity (r(2) > 0.999 for both drugs) with very low limits of detection (LODs) in the range of 0.14–0.84 ng/mL. Consequently, the proposed approach was efficiently adopted to analyze the co-administered drugs in their pharmaceuticals and in spiked human plasma with excellent % recovery between 97.4 and 102.2%. Finally, the method's greenness was evaluated using different metric tools, including Green Analytical Procedure Index (GAPI) and Analytical GREEnness (AGREE), which proved its excellent greenness.