Accurate glutamate monitoring in foodstuffs by a sensitive and interference-free glutamate oxidase based disposable amperometric biosensor.

L-Glutamate (L-Glu) is a well-known flavour enhancer that is present in several foodstuffs. Although L-Glu is generally recognized as safe, the use in foodstuffs remains controversial and then its fast and accurate monitoring represents an important issue. In this work a sensitive and interference-free disposable amperometric biosensor for glutamate monitoring in foodstuffs was developed. The biosensor was prepared by immobilizing glutamate oxidase through co-crosslinking with bovine serum albumin and glutaraldehyde onto a screen printed disposable platinum electrode modified with a permselective overoxidized polypyrrole film. The enzyme immobilization was optimized by using different experimental procedures. The optimized glutamate biosensor was integrated in a flow injection system and characterized in terms of linearity (0.005-1.0 mM, r2 = 0.992), limits of detection (1.8 μM) and quantitation (5.4 μM), repeatability (RSD < 3%) and stability of response under operational conditions (up to 50 h, over 400 analysis). The biosensor showed also excellent anti-interference characteristics towards the main electroactive interferents present in food matrices, and this allowed the application to the accurate monitoring of glutamate in different foodstuffs.