Patent ID: 7054759

Claim:
A concentration measuring method comprising: selecting a calibration curve optimum for computing concentration of a measurement target substance from a plurality of calibration curves based on an output from a reaction system containing the target substance and a reactant capable of reacting with the target substance; and computing the concentration of the target substance based on the optimum calibration curve and the output; wherein each of the calibration curves is prepared based on a plurality of outputs generated upon lapse of a same reaction time from a plurality of standard reaction systems each containing a standard reagent of a known different concentration and the reactant; wherein the plurality of calibration curves differ from each other in reaction time based on which the calibration curves are prepared; wherein the plurality of calibration curves include a first calibration curve to be selected when the concentration of the target substance is predicted to be higher than a predetermined concentration threshold, and a second calibration curve to be selected when the concentration of the target substance is predicted to be lower than the concentration threshold; wherein the first calibration curve is prepared based on an output measured in an initial stage of the reaction between a standard substance of a known concentration and the reactant; and wherein the second calibration curve is prepared based on an output measured after the output as the base for the preparation of the first calibration curve is measured.