Derivative synchronous spectrofluorimetry: Application to the analysis of two binary mixtures containing codeine in dosage forms.

Two binary mixtures containing codeine (COD) with either ibuprofen (IBU), mixture 1, or with phenylephrine hydrochloride (PE), mixture 2, were analyzed using three simple eco-friendly spectrofluorimetric methods without the need to a prior separation step. The first method is derivative emission spectrofluorimetry using λ = 236 nm and 275 nm for mixtures 1 and 2, respectively. The second method is constant-wavelength synchronous spectrofluorimetry using ∆λ = 100 nm and 60 nm for mixtures 1 and 2, respectively. The last method is constant-energy synchronous spectrofluorimetry where a wave number interval of -7000 cm was used for the analysis of the two binary mixtures. All measurements were performed in acetate buffer pH 5 and thus no toxic volatile solvents were used increasing method greenness. High sensitivity was attained for the three studied drugs where the lower limits of quantitation of COD, IBU and PE reached 0.064, 0.512 and 0.087 μg/mL, respectively. Analysis of the two binary mixtures in their tablet and liquid dosage forms was performed with good accuracy and precision using the developed methods. The results of the proposed and reported methods were statistically evaluated using one-way ANOVA test and no significant difference among them was obtained. In addition, all aspects of ICH guidelines on analytical method validation were conducted.