Appts. for continuous determn. of oxido:reductase substrate(s) - contg. immobilised enzyme

摘要

Appts. for continuous determn. of substrates of oxidoreductase enzymes having O2, NAD, NADP or artificial redox mediators as acceptors comprises: a receiver (1) for standard solns., connected via a tube (2) with a sterilising filter (3) and hence with a sample injector (4); a manifold (5) connected via a tube (6) with the tube (2) between the receiver (10 and filter (3); a buffer soln. container (7) connected to the manifold (5) via a tube (ii) contg. an air bubble trap (12); at least one immobilised oxidoreductase enzyme located between the working electrode in the measuring cell (1) and the manifold; a waste soln. container (13) connected via tubes (14 and 14a) with the manifold (5) and measuring cell respectively; valves (V) between each of the standard soln. containers and the receiver (1), in each of the tubes (6,11 and 140 entering the manifold, and between the filter (3) and the junction between tubes (2) and (6); and a control device for controlling the pump (8) and all the valves according to a predetermined program. The tubes are plastics hoses. The tube (11) between the manifold and measuring cell has an oxidoreductase enzyme covalently immobilised on its inner surface. The measuring cell has a working electrode, a reference electrode, a counter electrode and potentiostat. A plastics (esp. polyamide) gauze bearing a covalently immobilised oxidoreductase is placed over the working electrode. For H2O2-forming or O2-consuming enzymes, the working electrode is a Pt, platinised glassy carbon, platinised graphite or Au electrode. For NADH- or NADPH-forming enzymes, the working electrode is a mediator-modified electrode with a potential below 200 mV (versus S,C,E.), esp. a polypyrrole-quinone-modified Pt or glassy carbon electrode or a mediator-modified carbon paste electrode. Alternatively, the measuring cell has photometric or fluorometric detector. ADVANTAGE - The appts. is simple than conventional continuous-flow injection systems.