Construction and evaluation of a promazinium cation-selective electrode

The construction of a plasticised PVC matrix-type promazinium cation-selective membrane electrode and its use in the potentiometric determination of promazine hydrochloride in pharmaceutical preparations are described. It is based on the use of the ion-associate species, formed by promazinium cation and tetraphenylborate (TPB) counter ion. The basic electrode performance characteristics are evaluated according to IUPAC recommendations. It exhibited a linear response for 1 x 10(-2) - 1 X 10(-5) M of promazine hydrochloride solutions with a cationic Nernstian slope over the pH range 2-6. Common organic and inorganic cations showed negligible interference. Direct potentiometric determination of 1 x 10(-2) - 1 x 10(-5) M aqueous promazine hydrochloride using this membrane electrode system showed an average recovery of 99.5\% with a mean standard deviation of 1.5\%. This electrode was successfully used for monitoring the titration of promazine hydrochloride with sodium tetraphenyl borate and for determining promazine hydrochloride in ampoules.