title: Multi-enzyme electrodes for the determination of starch by flow injection.
abstract: A tri-enzyme electrode has been developed for determining starch in a flowing stream based on amperometric monitoring of hydrogen peroxide at a potential of +600 mV versus a silver--silver chloride reference electrode. The nylon-based starch-sensing membranes (over a platinum electrode) were prepared from an enzyme cocktail containing various ratios of amyloglucosidase (AMG), mutarotase (MUT) and glucose oxidase (GO). The best starch-sensing membrane (to give the type A electrode) was made from an enzyme cocktail of AMG--MUT--GO (2000 + 100 + 100 U; where 1 U = 16.67 nanokatals), i.e., containing a high level of AMG. In this system, starch samples were first incubated with soluble alpha-amylase (alpha-AMY) (1000 U) for 1 h at room temperature prior to analysis with the tri-enzyme electrode. Attempts were also made to immobilize alpha-AMY on to nylon net, either alone or as a component of a four-membrane starch-enzyme electrode but starch signals were weak compared with those generated by starch pre-treated with soluble alpha-AMY. This system, associated with the type A starch electrode, not only exhibited a calibration of wide linear range (1 x 10(-4)-0.1% m/v starch) but also showed promising operational properties. It has excellent thermal stability over the range 30-70 degrees C.
authors: School of Chemistry and Applied Chemistry, University of Wales College of Cardiff, UK.
authors: J
authors: J
authors: Abdul Hamid
authors: G J
authors: GJ
authors: Moody
authors: J D
authors: JD
authors: Thomas
mesh_terms: D004566:Electrodes; D004800:Enzymes, Immobilized; D006861:Hydrogen Peroxide / Q000032:analysis; D013213:Starch / Q000032:analysis*
chemical_list: D004800:Enzymes, Immobilized; D013213:Starch; D006861:Hydrogen Peroxide