A phosphate sensor based on silver phosphate-modified electrodes

Abstract

A phosphate sensitive ion-selective electrode based on silver phosphate has been prepared by electrochemical deposition of silver on platinum and subsequent anodic dissolution of the deposited Ag in alkali phosphate solutions. The potential of these Ag 3PO 4 − modified electrodes is controlled by PO 3− 4 ions in the activity range of 3 × 10 −9 < a PO 3− 4 < 3 × 10 −5 at pH 7–10 and with a Nernstian slope of about −20 mV/p a PO 3− 4 . Strong interference is observed with Cl − ions. The electrode is suitable for the potentiometric titration of phosphate ions and for the determination of phosphate by the standard addition method according to Gran.