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 Zn^II and Pb^II. The stoichiometric ratios of cephapirin versus Zn^II or Pb^II ions in these compounds are 1 : 1, 1 : 2 and 1 : 3 respectively. Cefoperazone gives one weak complex of molar ratio 1:1 with Zn^II ions, but it reacts with Pb^II ions forming two types of stable complexes of ratios 1 : 1 and 1 : 2. One complex 1 : 1 species occurs between cefuroxime and Pb^II but three complexes appear with Zn^II 

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 Zn^II ions which gave 1 : 1 : 2 complex. The formation of 2 : 1 : 1 complexes did not occur for all studied cephalosporins.