Flow-injection Potentiometric Detection of Phosphates Using a Metallic Cobalt Wire Ion-selective Electrode

Abstract

Flow-injection potentiometric detection of phosphate has been undertaken using a metallic cobalt wire ion-selective electrode. The electrode response to phosphate was characterised by potential readings of high stability versus a Ag/AgCl reference electrode, and results have shown that the electrode displays high sensitivity and selectivity towards the phosphate ion. The metallic cobalt wire electrode was used for the flow-injection potentiometric detection of phosphate using a 0.04 mol l ^{- 1} potassium hydrogen phthalate carrier at pH 5.0. A linear response with a slope of -38.00 ± 0.5 mV decade ^{- 1} change in phosphate activity was obtained in the range 1.0 × 10 ^{- 5} –5.0 × 10 ^{- 3} mol l ^{- 1} , and the detection limit was 1 × 10 ^{- 6} mol l ^{- 1} . The phosphate electrode described in this paper is robust, simple to use, highly selective, inexpensive and highly stable.