New solid state phosphate sensitive electrodes for routine environmental monitoring

Abstract

Highly selective and sensitive phosphate sensors have been fabricated by constructing a solid membrane disk consisting of variable mixtures of aluminium powder (Al), aluminium phosphate (AlPO 4) and powdered copper (Cu). Both binary and ternary electrode systems are produced. The ternary membranes exhibit greater selectivity over a wide range of concentrations. The ternary electrode with the composition 25% AlPO 4 , 25% Cu and 50% Al was selected as our preferred electrode. The newly fabricated ternary membrane phosphate selective electrodes exhibited linear potential response in the concentration range of 1.0 × 10 í1 to 1.0 × 10 í6 mol L í1. The electrodes also exhibit a fast response time of <60 s. Their detection limit is lower than 1.0 × 10 í6 mol L í1. The unique feature of the described electrodes is their ability to maintain a steady and reproducible response in the absence of an ionic strength control. The electrodes have a long lifetime and can be stored in air when not in use.