Potentiometric application of boron- and phosphorus-doped glassy carbon electrodes

Abstract

A comparative study was carried out of the potentiometric application of boronand phosphorus-doped and undoped glassy carbon samples prepared at the same heat treatment temperature (HTT 1000 ?C). The electrochemical activities of the obtained electrode materials were investigated on the example of argentometric titrations. It was found that the electrochemical behaviour of the doped glassy carbon samples are very similar to a Sigri (undoped) glassy carbon sample (HTT 2400 ?C). The experiments showed that the potentiometric response depends on the polarization mode, the nature of the sample, the pretreatment of the electrode surface, and the nature of the supporting electrolyte. The amounts of iodide, bromide, and of chloridewere determined to be 1.27 mg, 0.80 mg and 0.54 mg, respectively, with a maximum relative standard deviation of less than 1.1%. The obtained results are in good agreement with the results of comparative potentiometric titrations using a silver indicator electrode. The titrationmethod was applied to the indirect determination of pyridoxine hydrochloride, i.e., vitamin B6.

Phosphorus-doped and undoped glassy carbon indicator electrodes in controlled-current potentiometric titrations of bromide- or chloride-containing active ingredients in some pharmaceutical preparations

“…1, curves 2 and 3), because the change of the potential around the equivalence point obtained with P-GC10 is about three times greater than that obtained using a silver electrode. By comparing the behaviour of the Sigri-GC with that of the P-GC10 electrode it can be noticed that the total change of the potential was similar with both of them, as could be expected on the basis of titration curves of bromide in the model solution [30][31][32].…”

“…The microcomputer-aided [33] potentiometric (I = 1 A) titrations were carried out with a negatively polarized indicator electrode coupled to a Radiometer saturated calomel electrode (SCE) via a double-junction salt bridge ([GC(−)|SCE(+)]) [30][31][32]. In all experiments, only the electrode disc area was exposed to the solution.…”

“…In view of the fact that controlled-current potentiometric titrations with phosphorus-doped glassy carbon and Sigri glassy carbon indicator electrodes have been successfully applied for the determination of halides in model solutions [30][31][32], continuing on our previous study of argentometric determination of bromine-containing active ingredients in some drug formulations [6], the subject of this work was to investigate the possibility of application the above electrodes for the determination of bromide and chloride in some pharmaceutical preparation. Besides, a potentiometric titration procedure was applied, using a silver wire as indicator electrode.…”