Preparation and Study of Cephalexin Selective Electrodes and Their Application in Pharmaceutical Drugs

Abstract

A plastic membrane electrodes for the determination of cephalexin monohydrate were fabricated based on the use of cephaiexin-phosphotungstate as an active substance, and with different plasticizers, di-butyl phosphate (DBP), di-butyl phthalate (DBPH), di-octyl phthalate (DOP), tri-butyl phosphate (TBP) and o-nitro phenyl octyl ether (NPOE) in PVC matrix membranes. The study was carried out to investigate the electrode parameters, effect of pH and selectivity. Internal filling solution of 10-3 M Ceph + 10-3 M NaCl was used to fill the electrodes. The best electrodes were based on DBPH and DOP plasticizer which gave a slope 59.5 and 58.5 mV/decade, linear concentration range 10-4 – 10-2 M and detection limit of 5 x 10-5 and 3 x 10-5 M, respectively displayed good stability and reproducibility. The electrodes were used to determine the cephalexin monohydrate in oral suspension and capsules, the average recovery and standard deviation were (100.116 ± 0.393) and (100.344 ± 0.120), respectively. The results were compared with UV-derivative spectrophotometry (DS) and the results for the drugs obtained by first derivative are quite comparable with the recovery obtained by cephalexin selective electrodes.