TLC separation of fluoroquinolones: Searching for better selectivity

Fluoroquinolones are a relatively new group of chemotherapeutics used worldwide. They are approved for use as therapeutic agents and as feed additives in food producing animals in many countries. The misuse of these antibiotics in human and veterinary medicine has led to the loss of their efficacy and to the emergence of drug-resistant bacteria. Therefore, there is a need for developing analytical methods to monitor the levels of fluoroquinolone residues in biological fluids and edible animal tissues. In this paper, the optimal conditions for thin-layer chromatography (TLC) analysis of six veterinary fluoroquinolones, i.e., difloxacin, ciprofloxacin, norfloxacin, sarafloxacin, enrofloxacin, and flumequine are established. Good separation was achieved using 2-dimensional TLC on silica gel. Retention parameters for various chromatographic systems are compared. Chromatographic properties of four sorbents, i.e., plane silica gel and silica gel with bonded diol-, amino-, and cyanopropyl chains are discussed.