POTENTIOMETRIC DETERMINATION OF CLORAZEPATE DIPOTASSIUM IN HUMAN PLASMA AND IN PHARMACEUTICAL PREPARATION

摘要

Three developed techniques for the selective determination of clorazepate dipotassium were described. The three techniques were investigated with dioctyl phthalate (DOP) as a plasticizer in a polymeric matrix of polyvinyl chloride( PVC). These sensors for clorazepate cation were based on the use of the ion-association complexes of this cation with tetraphenyl borate, phosphotungestic acid and ammonium reineckate counter anions as ions exchange sites in a plasticized PVC matrix, either as ion selective membranes (sensor1, 1`and 1` `), microcoated wire (sensor 2, 2`and 2` `) or as microsized graphite sensor (sensor 3, 3`and3` `). All these sensors were prepared and fully characterized in terms of composition, life span, usable pH range, response time and temperature. These sensors showed near Nernstian responses with slopes in the range of 56.7-59.4 mv decade-1in a pH range of 4-7 over the concentration ranges of 1.0 x 10- 3- 1.0 x 10-7M and 1.0 x 10- 3- 1.0 x 10-6M for tetraphenyl borate sensors (1, 2and3) and the rest of the studied sensors; respectively. The electrodes exhibit good selectivity for clorazepate with respect to a large number of inorganic cations, sugars and many other exepients. The proposed sensors displayed useful analytical characteristics for the potentiometric determination of clorazepate in pure form, pharmaceutical preparation and in human plasma. The proposed electrodes offer the advantages of simplicity, accuracy and direct applicability to turbid and colored samples without any interference