Glucose biochip: dual analyte response in connection to two pre-column enzymatic reactions

This article describes a novel 'Lab-on-a-Chip' protocol generating two elec trophoretic peaks for a single analyte, based on the coupling of two differ ent pre-column enzymatic reactions of the same substrate followed by electr ophoretic separation of the reaction products. Such operation is illustrate d for the measurement of glucose in connection to the corresponding glucose oxidase (GOx) and glucose dehydrogenase (GDH) reactions. The pre-column en zymatic reactions generate hydrogen peroxide and NADH species, that are sep arated (based on their different charges) and detected at the end-column am perometric detector. The peak current ratio can be used for confirming the peak identity, estimating the peak purity, addressing co-migrating interfer ences, and deviations from linearity. A driving voltage of 2000 V results i n peroxide and NADH migration times of 93 and 260 s, respectively. Factors influencing the unique dual glucose response are examined and optimized. Th e concept can be extended to different target analytes based on the couplin g of two pre-column reactions with electrophoretic separation of the reacti on products.