Amperometrijski biosenzor za određivanje L-askorbinske kiseline u napicima pomoću imobilizirane askorbat oksidaze

Abstract

A novel biosensor for l-ascorbic acid determination in different beverages was elaborated. The ascorbate oxidase enzyme (AAO) from Cucurbita sp., EC 1.10.3.3, was immobilized on a screen-printed carbon electrode with poly(ethylene glycol) (400) diglycidyl ether (PEGDGE) as a crosslinking agent. The standards and samples were measured first with a blank electrode. An inert protein, bovine serum albumin (BSA), was immobilized on the surface of this electrode with PEGDGE. The BSA mass was equivalent to the mass of 10 U of AAO enzyme immobilized on the electrodes (0.021 mg). The linear measuring range for l-ascorbic acid was between 5 and 150 μmol/L. As l-ascorbic acid is a vital vitamin and a common antioxidant used in food industry, fruit juices and vitamin C effervescent tablets were examined. The results were compared to HPLC measurements.Razvijen je novi biosenzor za određivanje L-askorbinske kiseline (vitamina C) u sokovima pomoću askorbat oksidaze izolirane iz bundeve (Cucurbita sp.; EC 1.10.3.3), imobilizirane na grafitnoj elektrodi dodatkom polietilen glikol diglicidil etera (PEGDGE). Standardi i uzorci najprije su ispitani pomoću referentne elektrode. Zatim je inertni protein, i to goveđi serum albumin (BSA), imobiliziran na površinu elektrode pomoću PEGDGE. Masa BSA bila je jednaka masi 10 jedinica askorbat oksidaze imobilizirane na elektrodi (0,021 mg). Linearni raspon mjerenja bio je između 5 i 150 μmol/L askorbinske kiseline. Askorbinska kiselina je esencijalni vitamin i često se primjenjuje kao antioksidans u prehrambenoj industriji, pa je ispitan njezin udjel u voćnim sokovima i šumećim tabletama, a rezultati su uspoređeni s onima dobivenim tekućinskom kromatografijom