Application of Fourier transform-based algorithms to resolve spectral overlapping for UV spectrophotometric co-assay of spiramycin and metronidazole in tablets.

[Display omitted] • Fourier transform-based algorithms can be used for the spectral resolution of spiramycin - metronidazole binary mixtures. • A combination of the fast Fourier transform-based differentiation and multiple smoothing generates much higher intensity of the derivative signal than the default Savitzky-Golay algorithm. • The co-assay of spiramycin and metronidazole is possible with discrete Fourier transformed UV spectra. • UV spectrophotometric methods are environmentally friendly, technically simple, quick and economic as well as comparable to the RP-HPLC method reported. Fourier transform-based algorithms were investigated to resolve UV spectral overlapping of spiramycin and metronidazole in binary mixtures. UV spectra and ratio spectra were both subjected to fast Fourier transform-based first-order differentiation and discrete Fourier transform {i.e. using trigonometric functions such as sin x i – sin (x i + 450), cos x i + cos (x i + 450), sin 2x i – sin 2(x i + 450), cos 2x i + cos 2(x i + 450), sin x i – sin (x i + 600), cos x i + cos (x i + 600)} that followed by 3 passes of 17-point triangular smooth. Such signal transforms generated linear calibration graphs for either drug in the concentration range of 6.25 – 25 mg/L with R2 > 0.990. In comparison with the RP-HPLC reference method, the developed UV spectrophotometric methods had no significant difference in terms of accuracy and precision (p > 0.05) when quantifying spiramycin and metronidazole in their coated tablets. They are suggested as analytical quality control methods for their being environmentally friendly, technically simple, quick and economic. [ABSTRACT FROM AUTHOR]