Spectrophotometric methods for the determination of gemifloxacin in pharmaceutical formulations

Abstract

This paper describes two simple spectrophotometric methods for the determination of the antibiotic gemifloxacin mesylate (GFX) in pharmaceutical formulations. The first (A) is an indirect method in which oxidation of the drug with a known excess of cerium (IV) sulphate is followed by determination of the residual oxidant by adding excess methyl orange and measuring residual dye at 507 nm. The second (B) is a derivatisation method involving reaction of GFX with 1,2-naphthoquinone-4-sulphonate (NQS) in alkaline medium (pH 11) to form an orange-coloured product exhibiting maximum absorption (λmax) at 411 nm. The methods were linear in the concentration ranges 2–9 and 5–30 μg/mL for methods A and B, respectively, with intra-day precision (as RSD) <1.5% for both. When applied to the determination of GFX in pharmaceutical tablets, the results were in good agreement with those obtained by capillary electrophoresis. The two methods are useful for routine analysis of GFX in quality control laboratories.

Keywords

• Gemifloxacin mesylate
• Spectrophotometry
• 1,2-Naphthoquinone-4-sulphonate
• Pharmaceutical formulations