Patent ID: 7504020

Claim:
A method for determining a substrate contained in a sample solution on the basis of an oxidation current value, the method comprising: applying a first potential from a driving power supply of a measurement apparatus to an electrode portion of a biosensor for a first time period, the biosensor including the electrode portion, which comprises a counter electrode and a measuring electrode, and a reagent layer, which reacts with the sample solution supplied to the electrode portion; stopping the application of the first potential for a given time period; and applying a second potential, which is smaller than the first potential, to the electrode portion for a second time period after the given time period has passed; determining whether a kind of analyte liquid supplied to the biosensor is the sample solution or a standard solution based on the oxidation current value obtained by applying the first potential and the oxidation current value obtained by applying the second potential, wherein the standard solution is supplied to the electrode portion of the biosensor as the standard solution is used for controlling a precision of measurement of the measurement apparatus, wherein when the first potential is applied to the electrode portion of the biosensor to which the standard solution is supplied by the driving power supply of the measurement apparatus, the standard solution shows an oxidation current waveform which is definitely different from a waveform which is obtained when the first potential is applied to the electrode portion of the biosensor to which the sample solution is supplied, wherein when the second potential is applied to the electrode portion of the biosensor to which the standard solution is supplied, the standard solution shows an oxidation current waveform which is approximately the same as a waveform which is obtained when the second potential is applied to the electrode portion of the biosensor to which the sample solution is supplied, wherein the standard solution is one such that the value of the oxidation current, which flows when the first potential is applied to the electrode portion of the biosensor to which the standard solution is supplied by the driving power supply of the measurement apparatus, is larger than the value of the oxidation current which flows when the second potential is applied, and wherein the standard solution includes a reducing substance and a predetermined amount of substrate, and the precision of measurement of the measurement apparatus controlled by checking whether a measured substrate concentration is within a predetermined range or not.