Coconut-based plant tissue reactor for biosensing of catechol in flow-injection analysis

A novel plant tissue biosensor is proposed in this paper. Catechol is determined by the reduction of its oxidation product on glassy carbon electrode after a biocatalytic conversion to quinone in an on-line coconut-based reactor by flow injection analysis. The remarkably high polyphenol oxidase activity of the tissue is successfully associated to its high stability and physical feasibility to manufacture the bioreactor. The sensor retains its enzyme activity for at least one week. Catechol can be determined at micromolar range in a rate of up to 60-90 samples per hour with good precision (RSD 2%). Optimization of the experimental parameters including bioreactor and cell design is addressed. An interference study is also included showing the limitations and other possibilities of the use for this plant material. Applicability to river water analysis and waste water is illustrated. Such use of biocatalytic material apart from the electrochemical detector still holds great advantages for easy screening of new material sources for biosensing applications. (C) 1997 Elsevier Science B.V.