LAUSR

A new fast, cheap and efficient epoxy-amine immobilized enzyme reactor (IMER) is demonstrated. Polyethyleneimine (PEI) was used as the curing agent of an epoxy resin (bisphenol-A diglycidyl ether (BADGE)) in order to introduce a high number of reactive –NH2 groups at the substrate. A ratio mixture of 3:2 PEI:BADGE (w/w) was shown to be the most suitable for curing, taking into account the number of immobilization sites and the resistance of the material towards channeling. Electrochemical measurements made by a three electrode system, adapted at the IMER, showed that the Km value for immobilized glucose oxidase (GOx) was half the value commonly reported for GOx immobilized at PEI derived substrates. The IMER response decreased by around 41 % after one week of intense usage. Even so, the remaining activity was sufficient for quantifications of approximately 0.1 mmol L−1, merely requiring a new calibration of the reactor before its utilization. The developed system was applied to D-glucose quantification of beverage samples, requiring an injection volume of only 10 μL and a flow rate of 150 μL min−1 (almost 60 samples per hour). Low detection and quantification limits (1.94 and 5.89 μmol L−1, respectively) and a wide linear range (from 8 μmol L−1 to 2 mmol L−1) were also found, which are useful characteristics for quality control analysis.