Polypyrrole-based potentiometric phosphate biosensor

A phosphate biosensor based on potentiometric detection mode is described. Purine nucleoside phosphorylase (PNP) and xanthine oxidase (XOD) were immobilised into polypyrrole films for potentiometric measurement of phosphate in 0.05 M barbitone buffer (pH 7.8) which contain 10 mM inosine. A minimum detectable amount of 1.0 μM phosphate and a linear concentration range of 5–25 μM were achieved enabling sensitive potentiometric detection and a wide linear concentration range. The presence of uric and ascorbic acids had the least effect on the performance of the PPy–PNP–XOD–Fe(CN)64− biosensor and therefore will not have any effect on phosphate measurement at levels normally present in water.