Silver selective electrodes based on methyl-2-pyridyl ketone oxime, phenyl-2-pyridyl ketone oxime and bis[2-(o-carboxythiophenoxy)methyl]-4-bromo-1-methoxybenzene carriers

Abstract

Silver ion-selective electrodes based on methyl-2-pyridyl ketone oxime (MPKO), phenyl-2-pyridyl ketone oxime (PPKO) and bis[2-(o-carboxythiophenoxy)methyl]-4-bromo-1-methoxybenzene (CMBMB) carriers have been developed. The membrane solutions containing PVC, plasticizer, lipophilic ionic additive, and MPKO, PPKO or CMBMB were directly coated on the surface of graphite electrodes. The electrodes exhibited linear responses with Nernstian slopes of 59.8–60.5mV per decade within the range of 1×10−6M to 1×10−1M silver ion. The response times of the electrodes were <10s over the concentration range of 1×10−2M to 1×10−4M and they did not show a considerable divergence in their potential response over a period of 3 months. The electrodes exhibited good selectivities toward silver ion with respect to alkali, alkaline earth and several transition and heavy metal ions. The electrodes based on MPKO generally showed better selectivity for silver ion compared to the other two carriers. The electrodes based on MPKO and PPKO carriers can be used in a wide pH range of 2.5–8.5 and the one based on CMBMB is suitable in the pH range of 3.0–6.5. Application of the electrodes for potentiometric titrations and determination of Ag+ concentration in waste photographic solutions are reported.