Development of tyrosinase biosensor based on pH-sensitive field-effect transistors for phenols determination in water solutions.

An enzyme biosensor for the determination of 4-chlorophenol in water solutions based on potentiometric pH-sensitive field-effect transistors as semiconductor transducer and tyrosinase immobilised in saturated glutaraldehyde vapours as biorecognition element has been described for the first time. The main analytical characteristics were studied under different conditions, as well as the possibility to optimise these working parameters. Different factors, such as pH of immobilisation, the enzyme loading and time of immobilisation in glutaralaldehyde vapours were investigated with regard to the influence on sensitivity, limit of detection, dynamic range, and operational and storage stability. The best result gives a limit of detection close to 20 ppm and a dynamic range from 25 to 1000 ppm with sensitivity 2 mV mM(-1). The operational stability was not less-than15 h and the R.S.D. were approximately 3% for intra-sensors responses and approximately 7% for inter-sensors responses. The storage stability was >15 days.