Enzymatic Flow Injection Determination of Gamma-Aminobutyric Acid

γ-Aminobutyric acid (GABA) was determined by using flow injection analysis with a column of GABAse immobilized on glass beads. The NADPH produced was monitored fluorometrically. At a flow rate of 0.8 ml/min, peak heights were linear in the range 1-500 μM, and samples could be injected every minute. Nearly 100 % recovery of GABA was observed when GABA was added to infusions of green tea. ∗Permanent address: National Research Institute of Vegetables, Ornamental Plants and Tea, 2769 Kanaya, Shizuoka 428 JAPAN