Application of a flow injection fibre optic biosensor for the analysis of different amino acids

The analysis of different amino acids is described using a fibre optic biosensor previously described in its principles. This biosensor works according to the measurement principle of flow injection analysis (FIA) and consists of a fluorosensor and a measurement cell operating under pressure. In the measurement cell, enzymes and molecular weight enlarged coenzyme PEG (MW 20000)-N6-(2-aminoethyl)-NAD(H) are confined behind a solid ultrafiltration membrane. Assays for the analysis of L-phenylalanine and L-alanine were developed. The analysis frequency is in the range of 1 to 2 samples per hour, and the sensor stability was found to be sensitive to the stability of each enzyme system used. This effect was studied in detail. The L-alanine assay was found to be especially reliable, sensitive, specific, and highly selective for the L-enantiomer.