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Journal of Applied Sciences

Year: 2012 | Volume: 12 | Issue: 4 | Page No.: 315-325
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Authors

Abdulazeez T. Lawal

Samuel B. Adeloju

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Research Article

Polypyrrole Based Amperometric and Potentiometric Phosphate Biosensors: A Comparative Study

Abdulazeez T. Lawal and Samuel B. Adeloju
The preparation of two electrochemical (potentiometric and amperometric) phosphate biosensors is described and compared. Purine Nucleoside Phosphorylase (PNP) and xanthine oxidase (XOD) were co-immobilised via entrapment into polypyrrole (PPy) films by galvanostatic polymerization. Polypyrrole entrapment was achieved with 0.5 M pyrrole by using a polymerisation time of 200 sec and a mole ratio of 1:8 (6.2 U mL-1 XOD: 49.6 U mL-1 PNP) in both biosensors. Sensitive amperometric measurements were compared with those of potentiometric measurements obtained for PPy-PNP-XOD-Fe(CN)64¯ biosensors. A minimum detectable concentration of 1.0 μM phosphate and a linear concentration range of 5-20 μM were achieved with potentiometric PPy-PNP-XOD-Fe(CN)64¯ biosensor. In comparison, a minimum detectable concentration of 10 μM and a linear concentration range of 0.1-1 mM were achieved with amperometric biosensor. The presence of uric and ascorbic acids had the least effect on the performance of the amperometric and potentiometric PPy-PNP-XOD-Fe(CN)64¯ biosensors, therefore will not have any effect on phosphate measurement in both biosensors at levels normally present in water.
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