A voltammetric enzyme-linked immunoassay based on a new system of m- aminophenol(MAP)-H~2O~2-horseradish peroxidase (HRP) has firstly been developed and used for the detection of HRP and labelled HRP.HRP or labelled HRP catalyzes the oxidation reaction of MAP with H~2O~2,the product of which yields a sensitive voltammetric peak at potential of -0.46V(vs.SCE) in Britton-Robinson(B-R) buffer solution. By using this voltammetric peak, HRP can be measured with a detection limit of 3.0x10^-^9g/L and a linear range of 1.0x10^-^8-1.0x10^-^6g/L. The pure producd of H~2O~2 oxidizingMAP catalyzed by HRP was prepared with chemical method. The enzyme-catalyzed reaction has been investigated with electroanalytical chemistry,elemental analysis,UV- vis, IR ^1H NMR, ^1^3C NMR and MS spectroscopy. Under the selected enzyme-catalyzed reaction conditions,the oxidation product of MAP with H~2O~2 catalyzed by HRP is 2-amino-5-[(3-hydroxyphenyl) amino]-2, 5- cyclohexadiene-1,4-dione. The processes of the enzyme-catalyzed reaction and the electroreduction of the product of the enzyme- catalyzed reaction are described.

Key words: AMINOPHENOL, VOLTAMMETRY, ENZYME CATALYSIS, HYDROGEN PEROXIDE, IMMUNOASSAY, PROTON MAGNETIC RESONANCE SPECTROMETRY, HIGH SPEED LIQUID CHROMATOGRAPHY, ELEMENTAL ANALYSIS, ULTRAVIOLET SPECTROPHOTOMETRY, PROTON MAGNETIC RESONANCE SPECTROMETRY