AN IMPROVED FIA BIOSENSOR FOR THE DETERMINATION OF ASPARTAME IN DIETARY FOOD-PRODUCTS

A flow injection analysis (FIA) biosensor system was developed for the determination of the artificial sweetener aspartame (L-aspartyl-L-phe nylalanine methyl ester). The system consisted of an enzyme column of pronase immobilized on activated arylamine glass beads and a L-amino a cid oxidase electrode connected in series. The dipeptide bond of aspar tame was cleaved by immobilized pronase to release phenylalanine, whic h was in turn monitored by the enzyme electrode that used L-amino acid oxidase immobilized on a preactivated nylon membrane in combination w ith an amperometric electrode (platinum vs silver/silver chloride, 700 mV). The response of the FIA biosensor was linear up to 1 mM aspartam e with a lower detection limit of 25 muM and had good reproducibility (rsd 0.3%). The FIA biosensor was stable for at least 30 h of continuo us use at T(r). Each assay takes 4 min giving a sample throughput of 1 5 h-1. When applied to aspartame in dietary food products the results obtained agreed well with those reported by the product manufacturers.