POLAROGRAPHIC DETERMINATION OF STABILITY CONSTANT AND THERMODYNAMIC PARAMETERS OF Cd (II) COMPLEXES WITH ANTIBIOTICS AND CEFOPERAZONE

摘要

Polarographic technique was used to determine the charge and mass transfer with applied potential between dropping mercury electrode and solution interface of [Cd-antibiotics'-cefoperazone] system at pH = 7.30 ± 0:01,μ = 1.0M KNO3 at 25° and 35°. Cd~(2+) formed 1:1:1, 1:1:2 and 1:2:1 complexes with doxycycline, chlortetracycline, ox-ytetracycline, tetracycline, minocycline, amoxicillin and chloramphenicol used as primary ligands and cefoperazone as secondary ligand. The stability constant (log (3) varied from 1.88 to 9.67 showed that these drugs or in combination with cefoperazone or their metal complexes could be used for Cd toxicity. Thermodynamic parameters such as enthalpy change (AH), free energy change (AG) and entropy change (AS) of the complexes were also reported and it is clear from these data that the values of AS are more negative and AG are less negative at higher temperature. This confirmed that complexes are not stable at higher temperature.