Green Assessment of Sensitive Spectrofluorimetric Methods for Simultaneous Estimation of Formoterol Fumarate and...

Highly sensitive spectrofluorimetric methods were developed for the quantitative estimation of formoterol fumarate dihydrate (FFD) and fluticasone propionate (FP) in both authentic raw materials and marketed dosage forms using a micellar-enhanced spectrofluorimetric approach. The proposed methods are based on the determination of FP in the presence of FFD using the first derivative emission spectrofluorimetry. The peak amplitude of the emission spectra of the formed micellar fluorescence was measured at 465 nm after excitation at 236 nm (λ max of FP).The second method quantifies FFD in the presence of FP using second derivative emission spectrofluorimetry. This method measures the peak amplitude of the emission spectra of the formed micelle at 283 nm, where there is no interference from FP, following excitation at 214 nm. In these methods, the emission spectra of the target drugs are measured after micellar formation, with excitation wavelengths at 214 nm for FFD and 236 nm for FP. The fluorescence intensity was enhanced using β-cyclodextrin as a micellar system after optimizing parameters affecting native fluorescence, such as diluting solvents, surfactants, and varying concentrations of β-cyclodextrin. A linear relationship was observed between the fluorescence intensity and concentration for FP over the range of 50-100 ng/mL and for FFD over the range of 30-700 ng/mL. The developed methods are simple, sensitive, non-extractive, economical, and suitable for routine analysis of FFD and FP in their raw materials and combined marketed dosage forms. The proposed techniques were carefully validated for linearity, accuracy, precision, and specificity according to the International Council for Harmonization (ICH) guidelines, demonstrating high sensitivity with lower limits of detection and quantitation. Additionally, the analytical greenness of the suggested procedures was assessed using the Analytical Greenness Metric Approach (AGREE), the Red-Green-Blue model, and the Green Procedure Analytical Index (GAPI).