Quantitation of monosodium glutamate using immobilized glutamate oxidase/peroxidase and flow injection analysis

A rapid and sensitive now injection method is developed for tbe quantitatio n of glutamate in food samples. The method incorporates a covalently immobi lized glutamate oxidase and peroxidase bioreactor linked in tandem. The H2O 2 liberated from the glutamate samples as a result of enzymatic action is m onitored spectrophotometrically at 552 nm using 4-aminoantipyrine and 3-dim ethylaminobenzoic acid as a new chromogenic reagent. Glutamate calibration curves are linear up to 140 mu M with a detection limit of 1 mu M. Recovery yields from soup matrices are in the range 97 - 101%. Inter- and intra-day precision studies gave CV's of less than 3.5%. The immobilized enzymes sho w good storage and operational stabilities. Up to 40 samples h(-1) can be m anually analyzed. Excellent correlation is obtained from a comparison of th e glutamate content of various soup brands and matrix type (solid, condense d and broths) obtained by the proposed FI method with those obtained for th e same samples analyzed by the standard reference method (y = 0.99x + 0.034 ).