Development of an Amperometric Biosensor for β‐ N ‐Oxalyl‐ L ‐α,β‐Diaminopropionic Acid (β‐ODAP)

An amperometric method for the determination of the neurotoxic amino acid β‐ N ‐oxalyl‐ L ‐α,β‐diaminopropionic acid (β‐ODAP) using a screen printed carbon electrode (SPCE) is reported. The electrode material was bulk‐modified with manganese dioxide and used as a detector in flow injection analysis (FIA). The enzyme glutamate oxidase (GlOx) was immobilized in a Nafion‐film on the electrode surface. The performance of the biosensor was optimized using glutamate as an analyte. Optimum parameters were found as: operational potential 440 mV (vs. Ag/AgCl), flow rate 0.2 mL min −1 , and carrier composition 0.1 mol L −1 phosphate buffer (pH 7.75). The same conditions were used for the determination of β‐ODAP. The signal was linear within the concentration range 53–855 μmol L −1 glutamate and 195–1950 μmol L −1 β‐ODAP. Detection limits (as 3σ value) for both analytes were 9.12 and 111.0 μmol L −1 , respectively, with corresponding relative standard deviations of 3.3 and 4.5%. The biosensor retained more than 73% of its activity after 40 days of on‐line use.