Comparative Study of Different Spectrophotometric Methods for Simultaneous Determination of Tramadol and Paracetamol in Pharmaceutical Formulations

UV spectroscopy of tramadol (TRA) and paracetamol (PAR) shows substantial spectral overlap, which is a challenge for their simultaneous determination without preliminary separation. Three smart spectrophotometric methods based on the ratio spectra developed from the overlapping UV spectra of their binary mixture can be applied for a quantitative estimation of both drugs. The first derivative (DR¹) of the ratio spectra was computed, and then the amplitudes were measured at 268.7 and 237.4 nm for TRA and PAR, respectively. The mean centered ratio (MCR) of the spectra was estimated by measuring the MCR spectra at 279 and 241.5 nm for TRA and PAR, respectively. Finally, the dual wavelength (DW) method was applied by measuring the difference in absorbance at 224.1 and 268.5 nm for TRA determination and at 248 and 285.4 nm for PAR determination without any interference. All the above-mentioned spectrophotometric methods can be used to estimate TRA in the linear range of 10–110 μg/mL. Furthermore, PAR can be estimated in the linear range of 1–25 μg/mL. These methods were successfully applied to the analysis of the combined dosage form and bulk powder of TRA and PAR. The methods were validated according to the International Conference on Harmonization (ICH) guidelines, and the obtained results were statistically compared with those obtained by previously reported methods. No significant difference with respect to accuracy and precision was observed.