New Zn(II)-Selective Potentiometric Sensor Based on 3-Hydroxy-2-Naphthoic Hydrazide

A potentiometric membrane Zn(II) ion sensor is described based on 3-hydroxy-2-naphthoic hydrazide (HNH). The sensor exhibited a Nernstian response over a concentration range of 1.8 x 10(-7)-3.6 x 10(-1) mol l(-1), with a detection limit of 1.1 x 10(-7) mol l(-1). The best performance was achieved with a membrane composition of 33% PVC, 62% dibutylphethalate (DBP) and 5% HNH. It was found that in the pH range of 2.3-5.4, the potential response of the sensor was not affected by the pH. Furthermore, the electrode presented satisfactory reproducibility, fast response time (<18 s), and relatively good discriminating ability for Zn(II) ions with respect to many common cations, and transition metal ions. The sensor was applied to the determination of zinc in the sea water, tap water, urine and human hair.