Effect of plasticizer type on the potentiometric selectivity coefficient of electrodes for nitarte ion determination constructed by using PVC as polymeric membrane.

Abstract

Seven types of chemical sensors based on polymeric liquid membranes for determination of nitrate ion have been prepared by using 3-nitro-o-xylene (NOX), tri-butyphosphate (TBP), bis-(2-ethylhexyl)sebacate (DOS), o-nitrophenyloctyl ether (o-NPOE), tris-2ethylhexylphosphate (TEHP), dioctylphthalate (DOP) and dibutylphthalate (DBP) as plasticizers, tri-octyl methyl ammonium chloride (TOMACI) as ionophoreas ionophore and poly (vinyl chloride) (PVC) as matrix. The experimental data was validated by calibrating each constructed sensor against a reference AG/AgCl electrode. The calibration parameters for each sensor was determined by applying the method of the addition solutions and the potentiometric selectivity coefficient (K Pot AB) of each electrode was determined by applying the method of mixed solutions. The response of the sensors was determined in relation with the lipophilicity od each plasticizer used solvent-mediator, its dielectric constant (er), polarity and viscosity. No correlation between the calculated calues for K Pot AB of the electrodes and dielectric constant of the plasticizers was observed.