Amperometric enzyme electrodes for the determination of l-glutamate

• Published in: Talanta (Oxford) 1991, Vol.38 (1), p.49-55
• Main Authors: Villarta, Rhodora L., Cunningham, David D., Guilbault, George G.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biosensors; Biotechnology; Fundamental and applied biological sciences. Psychology; Methods. Procedures. Technologies; Various methods and equipments
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/0039-9140(91)80008-N

Electrodes for amperometric measurement of l-glutamate were prepared by immobilization of l-glutamate oxidase on an Immobilon-AV Affinity membrane and attachment to an oxygen/hydrogen peroxide sensor. The response of the hydrogen peroxide sensor was linear over the concentration range 5.0 × 10 −8−5.0 × 10 −4 M l-glutamate, with a limit of detection of 35n M. Attachment of a size—exclusion membrane (cut-off for molecular weight > 100) or of a hydrophobic oxygen membrane eliminated electro-oxidizable interferences, but the response was attenuated by a factor of 2–3. The response may be amplified 10-fold by co-immobilizing l-glutamate dehydrogenase with the l-glutamate oxidase. The electrode initially lost 25% of its activity but was then stable for more than 320 days and at least 200 assays. The electrode was successfully used to assay glutamate in a protein tablet and in several food products. A flow-injection system was assembled for the continuous assay of l-glutamate.