Polymeric membrane sensor for potentiometric determination of vanadyl ions

In this research, new electrodes were prepared by incorporating a new calix[4]arene derivative into a plasticized poly(vinyl chloride) matrix. Calibration plots with Nernstian slopes (29.9 +/- 1.1 mV/decade) for vanadyl ion were observed over a linear range of about four decades of concentration (1.0 x 10(-5) to 1.0 X 10(-1) mol dm(-3), at 25 degreesC). This electrode revealed a lower limit of detection of 3.9 x 10(-6) mol dm(-3). Conductometric data showed the relatively strong interaction between calix[4]arene and vanadyl ions. The results show that this electrode can be used in acetonitril and methanol media until 10% (v/v) concentration without interference. It has a short response time and can be used for more than two months without any considerable divergence in the potentials. The influence of membrane composition, the pH of the test solution, and the interfering ions on the electrode performance was investigated. The effect of temperature on the electrode response showed that the temperature higher than 50 degreesC deteriorates the electrode performance. The isothermal temperature coefficient of this electrode amounted to 0.0015 VdegreesC(-1). The results of application show that the electrode can be used successfully in present Cr3+ and Fe3+. (C) 2004 Elsevier B.V. All rights reserved.