Validated polarographic methods for the determination of certain antibacterial drugs

Two simple, precise, inexpensive and sensitive voltammetric methods for the determination of lomefloxacin (LFX), sparfloxacin hydrochloride (SFX), gatifloxacin (GFX), and moxifloxacin (MFX) were developed. The present methods were first used to explore the adsorption behavior of the four investigated antibacterial agents at a hanging mercury dropping electrode (HMDE), by a direct method and secondly by a modification via their complexation with PdCl(2). For the direct method, drugs were accumulated on HMDE, and a well-defined reduction peak was obtained in Britton-Robinson buffer of pH 7 for LFX and SFX, and pH 6 for GFX and MFX. The adsorptive stripping response was evaluated as a function of some variables such as the scan rate, pH, accumulation time and potential. For the modified method, the adsorptive behavior of Pd(II)-4-quinolone complexes at the HMDE developed a strippining voltammetry peak at a more negative potential than that of the free Pd(II) ions (-1.05 V). The limits of detection (LOD) were 2 x 10(-8) M, while the limits of quantification (LOQ) were 6 x 10(-8) M for the investigated drugs. The methods were applied to the determination of LFX, SFX, GFX, and MFX in biological samples and pharmaceutical preparations, and also compared with the official reference methods. Complete validation of the proposed methods was also done.