THE EFFECT OF SODIUM DODECYLSULFATE ON PROTOTROPIC EQUILIBRIA IN THE ALUMINUM(III)-OFLOXACIN SYSTEM

The protonation, hydrolytic and complexation equilibria in aluminum(III) + ofloxacin (Hoflo) solutions in the presence of sodium dodecylsulphate (SDS) have been studied by glass electrode Potentiometrie measurements in 0.1 mol/dm LiCl ionic medium, at 298 K. The results obtained indicate that in the presence of SDS the beginning of hydrolysis of Al ion shifts toward lower pH for approximately 1 pH unit in comparison with that in the absence of SDS. The obtained experimental data were consistent with the formation of only AI-(OH)4 complex with considerably higher stability constant (log ß3 .4 = 11.39 ± 0.05) than that in the absence of surfactant (log ß3 .4 = 13.73 ± 0.04). Protonation constants of ofloxacin anion (ofloxacinate, oflo) are significantly higher in the presence of SDS. In Al + oflo + SDS solutions, in the concentration ranges 0.6 < [Al] < 2.5 mmol/dm'; 0.6 < [oflo] < 7.5 mmol/dm and 3.0 < pH < 5.0 the formation of the following complexes, with their respective stability constants (logßp q r), was observed: Al(oflo) (10.28 ± 0.08); Al(OH)oflo (3.04 ± 0.10) and Al2(OH),oflo (4.56 ± 0.06) Introduction Ofloxacin (9-f luoro-3-methyl-10-(4-methyll -p iperazinyl) -7-oxo-2,3-dihydro-7H-pyr ido-( l ,2 ,3-de) l ,4benzoxazine-6-carboxylic acid), H(oflo), belongs to the class of fluorinated 4-quinolone antibiotics which finds use in the treatment of urinary and respiratory infections. It exhibits strong activity against Gram-negative and some Gram-positive bacteria, though many anaerobic strains are resistant. The mechanism of its action is based on inhibition of bacterial DNA gyrase thus, interfering with normal cell replication [1,2],