Fourier Transform Infrared Spectroscopic, Spectrofluorimetric Assays of Canagliflozin, and Stability-Indicating UV-Spectrophotometric Method for the Simultaneous Determination of Canagliflozin and Metformin.

Abstract

Green Fourier transform infrared (FTIR) spectroscopy, using potassium bromide (KBr) disc technique, eliminates the consumption of hazardous chemicals. Spectrofluorimetry for drugs that have native fluorescence. Mean centering of ratio spectra (MCRS) analysing overlapped spectra without preliminary separation. Three simple, accurate, and sensitive methods have been developed and validated for the determination of canagliflozin (CANA); one is a stability-indicating method for CANA and metformin (MET) determination. Method A is FTIR using a KBr disc for CANA determination measuring alkyl halide C-F peak area centered on 1230/cm. Method B is spectrofluorimetry using Δ λ = 50 nm synchronous mode at a peak maximum of 291.8 nm for CANA determination using methanol as solvent. Method C is a stability-indicating MCRS method measuring the peak amplitude of CANA and MET at 306.2 and 246.6 nm, respectively, in their mixture with complete CANA oxidation degradation. The linear ranges were: FTIR spectroscopy, 1.50-24.70 μg/mg CANA; spectrofluorimetry, 100.00-600.00 ng/mL CANA; and MCRS, 1.00-25.00 μg/mL CANA and 1-30 μg/mL MET. All results were statistically compared with a reported method: no significant difference was observed. The proposed methods can be used efficiently for routine analysis in QC laboratories. A green FTIR method utilizes only one reagent, KBr. Spectrofluorimetry using a constant wavelength synchronous scan of CANA native fluorescence in nanogram concentrations overcomes conventional excitation/emission spectra drawbacks and proves that the solvent effect in the fluorescence intensity differs according to concentration used. Stability-indicating MCRS determines the studied drugs in bulk, pharmaceutical formulations, accelerated and long-term stability study samples.