An oxygen-rich fill-and-flow channel biosensor

An oxygen-rich fill-and-flow channel biosensor has been developed for the measurement of glucose in wine. Glucose oxidase (GOD), immobilised in carbon paste (CP), was located in a well adjacent to a downstream detector electrode. When the analyte solution flows, hydrogen peroxide produced in the enzyme reaction is swept down to the detector electrode. Mineral oil and Kel-F oil (poly(chlorotrifluorethylene)) were used to prepare an enzyme layer of GOD within a CP. The hydrophobicity of the CP confined the reaction between the enzyme and its substrate to the surface of the enzyme layer. The oxidation current of hydrogen peroxide was sensitive to the enzyme loading but insensitive to mass transport variations such as flow rate. This response was, therefore, limited by the kinetics of the reaction between the enzyme and the substrate. For Kel-F oil, which can support a high concentration of dissolved oxygen, good reproducibility and greater dynamic range was obtained and the response did not decrease after degassing for 40 min with argon. Analysis of wine samples showed good agreement with the values obtained by spectrophotometric enzyme assay.