Concentration measuring method

A concentration measuring method for computing concentration of a measurement target substance based on an output from a reaction system containing the target substance and a reactant capable of reacting with the target substance, and a specific calibration curve showing a relationship between the concentration of the target substance and the output;

• wherein the specific calibration curve is prepared as a composite of a first calibration curve and a second calibration curve, the first calibration curve being prepared based on an output measured in an initial stage of the reaction between a standard substance of a known concentration and the reactant, the second calibration curve being prepared based on an output measured after the output as the base for the preparation of the first calibration curve is measured;
• and
• wherein the specific calibration curve comprises a higher concentration portion for a concentration range higher than an intersection concentration which corresponds to an intersection of the first calibration curve and the second calibration curve, and a lower concentration portion for a concentration range lower than the intersection concentration, the higher concentration portion comprising a portion of the second calibration curve for a concentration range higher than the intersection concentration, the lower concentration portion comprising a portion of the first calibration curve for a concentration range lower than the intersection concentration.

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 are prepared by measuring, at a plurality of measurement time points, outputs from the plurality of standard reaction systems each containing a standard reagent of a known different concentration and the reactant, each of the calibration curves corresponding to a respective one of the measurement points;
• and
• wherein the selection of the optimum calibration curve is performed based on an output measured in a time period in which the reaction between the target substance and the reactant is in an initial stage.