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

ABSTRACT A rapid and sensitive flow injection method is developed for the quantitation of glutamate in food samples. The method incorporates a covalently immobilized glutamate oxidase and peroxidase bioreactor linked in tandem. The H2O2 liberated from the glutamate samples as a result of enzymatic action is monitored spectrophotometrically at 552 nm using 4-aminoantipyrine and 3-dimethylaminobenzoic acid as a new chromogenic reagent. Glutamate calibration curves are linear up to 140 μM with a detection limit of 1 μM. 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 show good storage and operational stabilities. Up to 40 samples h−1 can be manually analyzed. Excellent correlation is obtained from a comparison of the glutamate content of various soup brands and matrix type (solid, condensed and broths) obtained by the proposed FI method with those obtained for the same samples analyzed by the standard r...