Determination of sulphite by use of a fiber-optic biosensor based on a chemiluminescent reaction

A fiber-optic biosensor based on the immobilization of sulphite oxidase and peroxidase on different membranes, and subsequent detection of luminol chemiluminescence has been developed. The response was linear in the concentration ranges of 1 to 100 μM and 3.2 to 320 μM, with a detection limit (signal-to-noise ratio = 3) of 0.5 μm sulphite. A Nucleopore polycarbonate membrane proved to be superior to the chemically preactivated ones. The effect of pH, buffer, and immobilization conditions, as well as the elimination of ascorbic acid interference are also discussed. The feasibility of the biosensor developed was demonstrated by assaying the sulphite content of different food samples.