American Journal of Analytical Chemistry, 2013, 4, 521-530 http://dx.doi.org/10.4236/ajac.2013.410066 Published Online October 2013 (http://www.scirp.org/journal/ajac) Sensitive Spectrofluorimetric Method for Determination of Fluoroquinolones through Charge-Transfer Complex Formation Jasmin Shah * , M. Rasul Jan, Inayat Ullah, Sultan Shah Institute of Chemical Sciences, University of Peshawar, Peshawar, Pakistan Email: * jasminshah2001@yahoo.com Received June 15, 2013; revised July 15, 2013; accepted August 2, 2013 Copyright © 2013 Jasmin Shah et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT A sensitive spectrofluorimetric method was developed for determination of ciprofloxacin (CPFX), levofloxacin (LEV), gatifloxacin (GAT) and moxifloxacin (MOX) in pure, commercial formulations, human urine and plasma. The method is based on charge-transfer (CT) complex with chloranilic acid. Fluorescence intensity of the complexes was measured at emission wavelength ranging from 445 - 492 nm with excitation wavelengths from 285 - 330 nm. At optimum ex- perimental conditions, a linear calibration plot was obtained in the concentration range of 20 - 1000 ng·mL −1 , 60 - 320 ng·mL −1 , 20 - 800 ng·mL −1 and 20 - 100 ng·mL −1 for CPFX, LEV, MOX and GAT, respectively with good correlation coefficient in the range of 0.9929 - 1.0 in methanolic medium. The limit of detection and limit of quantification were found to be 5 ng·mL −1 and 18 ng·mL −1 for CPFX, 12 ng·mL −1 and 40 ng·mL −1 for LEV, 8 ng·mL −1 and 19 ng·mL −1 for MOX, 6 ng·mL −1 and 19 ng·mL −1 for GAT, respectively. The method was found free of interferences from excipients used as additive in pharmaceutical preparations, some common cations and compounds present in urine and plasma as well as co-administered analgesic, vitamins and other drugs. The method was successfully applied for quantification of selected fluoroquinolones in commercial formulations and also in spiked human urine and plasma samples with percent recoveries of 100.0 ± 1.56 and 100.2 ± 1.29 respectively. Keywords: Fluoroquinolones; Chloranilic Acid; Charge-Transfer Complex; Spectrofluorimetry; Pharmaceutical Formulations; Biological Samples 1. Introduction Fluoroquinolones are a family of one of the most suc- cessful and important classes of manmade broad spec- trum antibiotics. They are receiving a significant atten- tion due to their broad spectrum activity, potency, vari- able indications, well oral bioavailability, good tissue absorbing, longer elimination half-life and excellent pharmacokinetic profile. As a result, fluoroquinolones have become a therapeutically effective class of antim- icrobial agents over the last decade. No other classes of antimicrobial agents have grown so rapidly or have been developed with such interest by pharmaceutical research companies. This class is among the world’s most used antimicrobial drugs in community and hospital settings [1-3]. Fluoroquinolones are generally considered well tolerable because most of their side effects are mild and serious effects occur rarely [4,5]. Fluoroquinolones are widely used to treat human and veterinary diseases [5-7]. Fluoroquinolones can enter cells easily and therefore are often used to treat intracel- lular infections. They are extremely useful for the treat- ment of a number of infections, including urinary tract infections, soft tissue and fluid infections, respiratory infections, bone-joint infections, typhoid fever, sexually transmitted diseases, prostatitis, community acquired pneumonia, acute bronchitis and sinusitis. They are par- ticularly used in bacterial urinary infections and also for infections whose antimicrobes possess great resistance. The broad spectrum antimicrobial activity, excellent bioavailability, good tissue penetration and long plas- matic stocking life, all have made fluoroquinolones, a special class of drugs [8]. Thorough study of the literature reveals that several methods have been developed for the determination of fluoroquinolones in bulk, pharmaceutical dosage form and biological samples based on wide array of instru- * Corresponding author. Copyright © 2013 SciRes. AJAC