International Journal of Multidisciplinary Comprehensive Research

A New Spectrophotometric Method for the Determination of Levofloxacin in Pharmaceutical Formulations via Ion-Pair Complex Formation with Bromothymol Blue

Ghada Fathi Saleh¹, Fayhaa Hassan Ali Ahmad²

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Abstract

A simple, sensitive, and cost-effective spectrophotometric method has been developed and fully validated for the quantitative determination of levofloxacin (LVX) in bulk drug substance and pharmaceutical dosage forms. The method is based on the formation of a yellow-coloured ion-pair complex between the protonated piperazinyl nitrogen of levofloxacin and the anionic dye bromothymol blue (BTB) in an acidic aqueous medium (pH 3.5), followed by extraction of the complex into chloroform and measurement of absorbance at 415 nm. Critical experimental variables were systematically optimized using a Box–Behnken response-surface design; the optimized conditions were subsequently verified by the traditional univariate approach to confirm agreement. Chloroform was selected on the basis of analytical performance; all extractions were performed in a well-ventilated fume hood in compliance with local safety regulations, and solvent volumes were limited to 5.0 mL per assay to minimize environmental impact. The greenness of the method was examined using the AGREE (Analytical GREE ness) scoring of the method, and the scoring produced a score of 0.54, which was deemed appropriate for the extraction-based visible spectrophotometric methodology. Under the optimal conditions, Beer’s law was satisfied over 1.0–20.0 μg mL⁻¹ and the molar absorptivity was 3.24 × 10⁴ L mol⁻¹ cm⁻¹. Detection and quantification limits were 0.31 and 0.94 μg mL⁻¹, respectively. The method was tested in accordance with ICH Q2(R1) criteria involving robustness determination by the Youden–Steiner strategy. The mean percent recovery from spiked samples was between 99.6 and 100.5%, with relative standard deviations below 2.0%. It was statistically compared to a reference HPLC method and the results were corroborated as 95% confidence interval equivalent. The proposed approach provides a broader Beer’s law range, similar molar absorptivity, and a more stringent ICH-compliant validation method than established methods for levofloxacin.

Keywords: Multidisciplinary Research, Engineering, Technology, Mathematics, Management, Medical Sciences, Social Science, Education, Agriculture, Computer Application, Economics, Entrepreneurship, Human Resources Management, Information Technology, Law, Life Sciences, Strategic Management, Sociology, Microbiology, Nursing, Pharmacy, Physical Education, Political Sciences, Psychology

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