Construction a PVC-membrane sensor based on 4′-nitro-benzo-15-Crown-5 for determination of Ag+ ion

Since heavy metal ions are non-biodegradable and can be accumulated in soft tissues, they are considered as the serious source to pollute the biosphere throughout the world and cause many healthy and physiological diseases [1]. Therefore, the selective and sensitive determination of heavy metals is of increasing interest [2]. Potentiometric ion selective electrodes (ISEs) are one of the most important types of chemical sensors [3]. In this research work, a polyvinyl chloride membrane electrode for measurment of silver(I) ion was constructed based on 4′-nitro-benzo-15-crown-5 as a ionophore. Central composite design (CCD) was applied as experimental design strategies to screen and optimize the influence of membrane ingredients on the electrode performance [4]. The aim of the experimental design is to reduce the number of the experiments for saving the time, as well as, the used material and also the cost, and achieving the reliable results [5]. The proposed electrode has a linear range of 1.0×10−5 to 1.0×10−2 M with respect to Ag+ ion, with a Nernstian slope of 60.1±0.4mV decade−1, and a detection limit of 7.58×10−6 M at pH 5. The electrode has a response time about 5 s with relatively good life time. It could be used in a pH range of 2.5-5. The proposed electrode was applied as an indicator electrode in the potentiometric titration of Ag+ cation with standard solution of sodium chloride.