Development of xylitol oxidase-based flow injection analysis for monitoring of xylitol concentrations Original Research Article

A flow injection method for monitoring xylitol was developed using xylitol oxidase (XYO) immobilized on a VA-Epoxy Biosynth E3-support. The immobilized XYO cartridge had a good operational lifetime (up to 24 h) and storage stability (up to 1 month). The XYO-FIA system with an oxygen electrode was investigated systematically regarding the factors that can affect enzyme activity, such as pH, reaction temperature, carrier solution and sample matrix. In order to attain high activity of the immobilized XYO, potassium phosphate solution (1 M) with 0.5 g l−1 Triton X-100 adjusted to pH 8.5 was used as the carrier solution. Sample matrix effects on the immobilized XYO were also investigated. High concentrations of some components (arabinose, 20 g l−1; xylose, 30 g l−1; NaCl, 30 g l−1) in the sample had significant inhibitory effects on the response of the XYO-FIA system. The performance of the XYO-FIA system was tested by using different sample injection volumes (75–250 μl) and carrier flow rates (0.7–2.0 ml min−1).