Determination of Glucose in Nonalcoholic Beverages by a Biosensor Coupled with Microdialysis Fiber Samplers

Abstract

Glucose in soft drinks, fruit juices, and milk was determined by an interference-free amperometric biosensor coupled with microdialysis fiber samplers. The biosensor was based on glucose oxidase (GOx) immobilized on a platinum electrode by an electroproduced bilayer of overoxidized polypyrrole (Pt/PPyox,GOx/PPyox). The first undercoating of PPyox entrapped GOx, and the second, grown onto the first, limited glucose diffusion, hence improving linearity of response. Such a biosensor coupled with microdialysis sampling extended the linear range to 500 mM. The biosensor response was not affected by sample pH variations in the range 2–10. The influence of flow rate on biosensor response was also investigated. The glucose response of the device in both continuous and discontinuous flow injection experiments showed good repeatability and sensitivity. Real samples containing high glucose concentrations were easily analyzed without pretreatment such as dilution or filtration. Results were in good agreement with those of the reference method.