Patent ID: 8309345

Claim:
A method for detecting an antigen using an electrochemical measurement device comprising a working electrode, a reference electrode, and a counter electrode, the method comprising steps of: (A) contacting an electrically conductive support with a sample solution, the support including a mixture of an antibody specifically reacting with the antigen and a multi-copper oxidase CueO; (B) measuring a current between the working electrode and the counter electrode by way of a potentiostat method, the potentiostat method comprising the steps of: (i) equipping the contacted support with the working electrode; and (ii) contacting the working electrode, the reference electrode, and the counter electrode with a buffer solution, the buffer solution having an ionic strength falling within a range of not less than 0.3 mM and not more than 1.0 mM, and containing a substrate of the multi-copper oxidase CueO; and (C) determining that the antigen is contained in the sample solution if the following inequality is satisfied: the current measured in the step >=1.5×(blank value) where the blank value is a current between the working electrode and the counter electrode measured by way of the potentiostat method under the condition that the antigen is not contained in the sample solution.