FLOW-INJECTION DETERMINATION OF GLUTAMATE IN HUMAN SERUM AND RAT-BRAIN SAMPLES WITH IMMOBILIZED GLUTAMATE OXIDASE AND GLUTAMATE-DEHYDROGENASE REACTORS

Glutamate oxidase was immobilized on non-porous glass beads and glutam ate dehydrogenase was immobilized on glass derivatives. These supports were employed for the construction of Single Bead String Reactors and Packed Bed Reactors, respectively, which in turn were linked to Flow Injection Analysis systems with either photometric or fluorometric det ection. Analytical working curves are linear in the range 1-200 mu mol /l for packed bed reactors and 10-500 mmol/l for single bead string re actors. The samples were pretreated depending on their origin and the applied measuring system. Optimal dilution factors were established fo r the two techniques. Optimal dilution ratios were established and the influence of several added substances was investigated. Recovery and method comparison studies including high performance liquid chromatogr aphy verified the accuracy of the proposed methods. Results from withi n-day and between-day measurements gave relative standard deviations o f 4.7 and 5.9% for serum samples and 2.5 and 4.0% for brain samples, r espectively.