Determination of moxifloxacin and iron(III) by formation of a complex compound Section A-Research Paper Eur. Chem. Bull. 2013, 2(1), 22-27 DOI: 10.17628/ECB.2013.2.22 22 MUTUAL SPECTROPHOTOMETRIC DETERMINATION OF MOXIFLOXACIN DRUG AND IRON(III) IONS BY FORMATION OF A COMPLEX COMPOUND W.F. El-Hawary [a,b] *, Faisal Kh. Al-Gethami [a] Keywords: Spectrophotometry - Moxifloxacin HCl - Iron(III) ions - Complex. A simple, new and sensitive spectrophotometric method has been developed for the quantitative determination of the drug Moxifloxacin HCl (MOX), in pure form and in pharmaceutical formulation; and Fe(III) ions. The method was based on the formation of a colored complex between the drug and Fe(III) ions. The maximum absorption wavelength was 450 nm for determination of both MOX and Fe(III) ions. Beer’s law was obeyed in the concentration range of 14.45 – 394.2 µg mL -1 (r 2 = 0.998) for determination of MOX and 2.8 – 22.4 µg mL -1 (r 2 = 0.97) for determination of Fe(III) ions. The conditions for complex formation were studied and optimized to obtain the highest absorbance available. The method was successfully applied for the analysis of commercial tablets (Maxim), and the recovery study reveals that there is no interference from the common excipients that are present in tablets. The results obtained by the proposed method were compared with that obtained by a standard reference one. Statistical comparison of the results was performed with regard to accuracy and precision using student’s t-test and F-test at 95% confidence level. The results proved that there no any significant difference, regarding accuracy and precision, between the two compared methods. *Corresponding Author E-Mail: waheedfathi@yahoo.com [a] Chemistry Department, Faculty of Science, Taif University, Taif, Saudi Arabia [b] Chemistry Department, Faculty of Science, Cairo University, Giza, Egypt Introduction Moxifloxacin (MOX) (Scheme 1) is a new fourth generation 8-methoxy fluoroquinolone. Its chemical name is [1-cyclopropyl-7-(S,S)-2,8-diazabicyclo(4.3.0)-non-8-yl-6- fluoro-8-methoxy-1,4-dihydro-4-oxo-3-quinoline carboxylic acid hydrochloride]. The drug was developed primarily for the treatment of community acquired pneumonia and upper respiratory tract infections. It is active against Gram negative pathogens, Gram positive cocci, aerobic intracellular bacteria, atypical organisms and anaerobic bacteria 1 . It has an empirical formula C21H24FN3O4. HCl with molecular weight 437.89. The drug is an odorless yellow crystalline powder with a melting point in the range 324 – 325 °C. The pH of its 0.1% aq. solution is 4.0 - 5.0. The drug base is sparingly soluble in water, slightly soluble in ethanol (96%) and practically insoluble in acetone; but the hydrochloride form of the drug is fairly soluble in water 2 . Only a little is available in the literature about the analytical determination of MOX, this is may be attributed to the relatively recent abundance of the drug. However, several methods are known for quantitative determination of MOX, including spectral 1,3-12 , chromatographic 13-25 and electroanalytical techniques. 9,22,26-29 The chromatographic method for the determination of MOX requires an automated system, which is not available in many research laboratories. Therefore, it was considered worthwhile to develop rapid and sensitive procedures suitable for the routine quality control analysis of the investigated drug. Spectrophotometric methods still belongs to the most frequently used analytical techniques in pharmaceutical analysis, which gives practical and significant economic advantages over other methods. So, the present study is an investigation and developing a new spectrophotometric method for the determination of MOX in pure form and in its pharmaceutical formulation; and Fe(III) ions, based on the formation of a colored complex compound. Scheme 1. Chemical structure of moxifloxacin (neutral form). Experimental Materials and reagents All chemicals used in the present investigation were of the highest purity grade chemicals. Ferric oxide was obtained from Sigma-Aldrich products and ferric chloride was obtained from Fluka. Pure MOX was provided by Jamjoom Pharma, Jeddah, KSA. MOX tablets (Maxim) was produced