Development and demonstration of an immobilised-polyphenol oxidase bioprobe for the detection of phenolic pollutants in water Original Research Article

The development of a portable, disposable bioprobe incorporating mushroom polyphenol oxidase immobilised on a synthetic membrane for this purpose is described for the detection and semi-quantification of phenolic pollutants in water. The enzyme, immobilised on a nylon membrane together with 3-methyl-2-benzothiazolinone hydrazone, produced ranges of maroon colours in phenolic solutions and orange colours in cresylic solutions. The colour intensities produced were found to increase proportionally with increasing substrate concentration after 5 min exposure to the substrates. The bioprobe had a broad substrate specificity and was sensitive to substrate concentrations down to 0.05 mg l−1. The enzyme activity of the bioprobe was not affected in a pH range from 4 to 10 and in a temperature range from 5°C to 25°C. The bioprobe activity was not affected by various concentrations of salt and metal ions and was able to detect and semi-quantify phenolic substrates in industrial effluent samples. The bioprobe could be stored for 1 month without loss of enzyme activity. These features indicate that the commercialisation of such a bioprobe is feasible.