Barium(II)-PVC Membrane Sensor Based on 4-4′-Methylenediantipyrine as a Neutral Carrier

Abstract

A highly selective and sensitive poly(vinyl chloride) membrane electrode, using 4-4′-Methylenediantipyrine as an ionophore, has been prepared and examined as a Ba²⁺-selective electrode. The influence of the anion excluder (sodium tetraphenyl borate, NaTPB) and the effect of the plasticizers dibutyl phthalate (DBP), nitrobenzene (NB), and benzyl acetate (BA) were studied. The best performance was obtained with the sensor having a membrane composition (w/w) of (MAP, 2.0%), (PVC, 30%), (NB, 66%), (NaTPB, 2.0%) with a wide working concentration range of 1.0 × 10⁻⁶ to 1.0 × 10⁻² M between the pH values of 3.4 and 10.6. Furthermore, a Nernstian slope of 29.7±0.3 mV/decade of activity was demonstrated with a response time of 15 s. The sensor could be used over a period of 2 months with no potential divergence, revealing a good selectivity for a broad variety of cations including alkali, alkaline earth, heavy and transition metals. Regarding the practical applicability of this sensing device, it was successfully applied for the Ba²⁺ ions detection in a lithophone pigment and as an indicator electrode in the potentiometric titration of the under study cations.