Development of amperometric biosensors for the determination of glycolic acid in real samples
(EN)
Tsiafoulis, C. G.
(EN)
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
(EL)
Tsiafoulis, C. G.
(EN)
The first enzyme-based biosensors capable of determining glycolic acid in various complex matrixes, such as cosmetics, instant coffee, and urine, are presented in this paper. Two separate designs, both based on a three-membrane configuration consisting of an inner cellulose acetate membrane (CA) and an outer polycarbonate membrane (PC), which sandwich a membrane bearing the biomolecule(s), are proposed. Glycolate oxidase was immobilized onto a modified polyethersulfonate membrane by means of chemical bonding, and glycolate oxidase/catalase enzyme mixture was immobilized into a mixed-ester cellulose acetate membrane through physical adsorption. The membrane assemblies were mounted on an amperometric flow cell (hydrogen peroxide detection at a platinum anode poised at +0.65 V vs Ag/AgCl/3 KCl) or on an oxygen electrode, respectively. Both configurations were optimized with respect to various working parameters. The proposed biosensors are interference-free to common electroactive species and were successfully applied for the determination of glycolic acid in various samples, showing an excellent agreement with a reference photometric method. The validity of the proposed method in samples, in which the reference method was not applicable, was tested with recovery studies. Values of 102 +/- % were obtained. Inherent interference of oxalic acid was manipulated by using a primary amine-containing buffer and the enzyme catalase. Both systems were designed in order to be compatible with the current technology of the most widely used commercial analyzers.
(EN)
