Patent ID: 8882987

Claim:
A method comprising detecting an abnormal waveform in a biosensor, which includes at least a working electrode and a counter electrode and measures an oxidation or reduction current value between the working electrode and the counter electrode, to determine a quantity of a base substance, wherein the detecting of the abnormal waveform is performed by applying a voltage between the working electrode and the counter electrode based on a voltage application pattern having a halt period between a first application period and a second application period, comparing the oxidation or reduction current measurement value obtained in the first application period of applying the voltage with the oxidation or reduction current measurement value obtained in the second application period of applying the voltage, and determining that the oxidation or reduction current measurement value obtained in the first application period and the oxidation or reduction current measurement value obtained in the second application period are not output when a difference between the oxidation or reduction current measurement value obtained in the first application period and the oxidation or reduction current measurement value obtained in the second application period is outside a predetermined range; obtaining P values in formula (1) in the first and second application periods, when the voltage is applied according to the voltage application pattern, P ( t )= X ( t )− X ( t −const) (1), wherein , t represents time, T 0 =first application period start time, T 1 =first application period end time, T 2 =second application period start time, T 3 =second application period end time, X(t) is a measured current value in the second application period ranging from T 2 to T 3 when the time t ranges within the second application period, X(t−const) is a measured current value in the first application period ranging from T 0 to T 1 , and const represents a time difference between the second application period start time T 2 and the first application period start time T 0 ; comparing the X(t−const) in the first application period with the X(t) in the second application period; and outputting no measurement values when a difference P value between the X(t−const) and X(t) is outside a predetermined range.