Abstract: A residual chlorine measuring apparatus includes: a detection electrode that is immersed in a sample solution, the detection electrode being made of gold or platinum; a counter electrode that is immersed in the sample solution, the counter electrode being made of silver/silver chloride; a voltage applying device that applies an applied voltage between the detection electrode and the counter electrode; an ammeter that measures an oxidation-reduction current flowing between the detection electrode and the counter electrode; and an arithmetic controller that controls the voltage applying device and acquires the oxidation-reduction current measured by the ammeter.

Abstract: A residual chlorine measuring apparatus includes: a detection electrode that is immersed in a sample solution, the detection electrode being made of gold or platinum; a counter electrode that is immersed in the sample solution, the counter electrode being made of silver/silver chloride; a voltage applying device that applies an applied voltage between the detection electrode and the counter electrode; an ammeter that measures an oxidation-reduction current flowing between the detection electrode and the counter electrode; and an arithmetic controller that controls the voltage applying device and acquires the oxidation-reduction current measured by the ammeter.

Abstract: A quantification method includes a calibration curve preparing step to measure a standard solution, which has been prepared by adding sodium ions so that a sodium ion content of the standard solution is equaled to a sodium ion content of a sample to be measured with a method employing a reaction that activates a limulus reagent and/or a biochemical luminescent reaction caused by ATP, luciferin, and luciferase, and to prepare a calibration curve that represents a relation between a measurement value and an amount of a component to be measured; a sample measuring step to measure the sample to be measured with a method being the same as that used in the calibration curve preparing step; and a quantifying step to find, by using the calibration curve, an amount of the component to be measured in the sample to be measured from a measurement value in the sample measuring step.