Development of an interferent free amperometric biosensor for determination of L-lysine in food

A highly selective, fast responding amperometric biosensor is described, useful for the determination of L-lysine in food. Common electrochemical interferences, like acetoaminophen and ascorbic acid have zero response at +100 mV applied onto a ruthenium/rhodium coated glassy carbon electrode covered with 1,2-diaminobenzene polymer. This novel transducer was coupled with L-lysine alpha-oxidase purified from Trichoderma viride and at the appropriate pH, classic substrate interferences from L-ornithine, L-arginine and L-phenylalanine are reduced to 3.4, 1.1 and 0.7% of the response to L-lysine (taken as 100%). No other amino acids respond. The sensor is inexpensive to produce, has excellent repeatability and very good reproducibility. Thus, the L-lysine (protein) content of foods can be almost specifically determined following rapid microwave digestion of the product. (C) 2000 Elsevier Science B.V. All rights reserved.