Immobilized enzyme electrode for the determination of l-lactate in food samples

• Published in: Analytica chimica acta Vol. 345; no. 1; pp. 37 - 43
• Main Authors: Villamil, M.J.Fernández, Ordieres, A.J.Miranda, Blanco, P.Tuñón
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 20.06.1997
• Subjects: Food samples; Immobilized enzyme electrode; l-lactate; TBO; TBO; Immobilized enzyme electrode; Food samples; l-lactate
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/S0003-2670(97)00046-9

A sensitive immobilized enzyme electrode for l-lactate is described. Toluidine blue O (TBO) and lactate dehydrogenase (LDH) were co-immobilized onto the surface of a graphite electrode by means of a dialysis membrane. l-lactate is oxidized to pyruvate by LDH in the presence of nicotinamide adenine dinucleotide NAD + which is then reduced to NADH. The NADH formed is electrocatalytically oxidized by TBO and the reduced mediator is detected at 0 V vs. a Ag AgCl reference electrode. Different dialysis membranes were tested in order to improve stability. The most stable enzyme electrode was fabricated with a benzoylated membrane, showing a half-life of eight days. This amperometric electrode responds fast and linearly to l-lactate in a concentration range 10 −6 − 6 × 10 −5 M. The limit of detection is 4 × 10 −7M. The enzyme electrode was applied to the determination of l-lactate in food samples. Results were compared to those obtained using a spectrophotometric method, showing a good agreement.