Screening and optimization of samarium-assisted complexation for the determination of norfloxacin, levofloxacin and lomefloxacin in their corresponding dosage forms employing spectrofluorimetry

Abstract

Multivariate strategy was applied for setting a fluorescent technique for the determination of three fluoroquinolones: norfloxacin (NOR), levofloxacin (LEV) and lomefloxacin (LOM) in their pure powder and dosage forms. Based on their known interaction with lanthanides, and augmented fluorescence intensity obtained by antenna effect at λ_ex/λ_em = 314/553, 312/553 and 310/556 for NOR, LEV and LOM, respectively, the current research was scrutinized. Four continuous factors were selected for study in the screening step by means of Plackett-Burman Design, where temperature factor was excluded for being non-significant and the other factors as volume of metal ion solution, pH and reaction time were evaluated through Central Composite Design. 3-D surfaces demonstrations and 2-D contour plots designated the factors interactions followed by optimization plots, which defined the best blend for factors conjunction. pH factor was the chief motor force affecting the response as the number of coordinated ligands formed depends on the pH, whereas 1:2 complex is the main species at higher pH values followed by the volume of metal ion solution and ended by little effect of the reaction time. Model verification was monitored, which showed the model superiority for the three fluoroquinolones, where all target points tested were in good agreement with the predicted ones. The linear range for the tested drugs were found to be 0.090-1.280 μg/mL for NOR, 0.068-1.448 μg/mL for LEV and 0.077-1.552 μg/mL in case of LOM, thus approving the suitability of this method for Quality Control testing. Furthermore, applying these conditions to test the fluoroquinolones in their pharmaceuticals was done as well as intra and inter-day effects as to confirm the validity of this technique for routine analysis. Recovery % and RSD were found to be 99.958 ± 0.797, 99.887 ± 0.935 and 100.427 ± 0.698 for NOR, LEV and LOM respectively in their pure powder. While it was calculated to be 100.200 ± 0.785, 100.530 ± 0.396 and 100.620 ± 0.896 for NOR, LEV and LOM in their corresponding dosage forms. This excellent precision and accuracy obtained in results impulse it to be one of the most appropriate methods for further analysis.

Keywords: % recovery; Central composite design; Fluoroquinolones; Plackett-Burman Design; Samarium; Spectrofluorimetry.