Polarographic studies on simple and mixed ligand systems involving cephalosporins

Chemistry Department, Faculty of Science, Minia University, Minia, Egypt Chemistry Department, Faculty of Science, Assiut University, 715 16-Assiut, Egypt Manuscript received 23 October 2000, accepted 20 April 2001 Differential pulse polarography and cyclic voltammetry have been chosen to follow up the metal-drug interactions at low concentrations in unbuffered solutions. Cephapirin, cefoperazone and cefuroxime form stable coordination compounds with ZnII and PbII. The stoichiometric ratios of cephapirin versus ZnII or PbII ions in these compounds are 1 : 1, 1 : 2 and 1 : 3 respectively. Cefoperazone gives one weak complex of molar ratio 1:1 with ZnII ions, but it reacts with PbII ions forming two types of stable complexes of ratios 1 : 1 and 1 : 2. One complex 1 : 1 species occurs between cefuroxime and PbII but three complexes appear with ZnII The formation constants of the metal ions with a mixture of cephalosporin and glycine ligands arc determined. Mixed ligand complexes with molar ratio of 1 : 1 : 1 [metal : gly : cephal) were observed for the all systems, except cefuroxime with ZnII ions which gave 1 : 1 : 2 complex. The formation of 2 : 1 : 1 complexes did not occur for all studied cephalosporins