Patent ID: 8557597

Claim:
A total organic carbon measuring method using an instrument, the instrument comprising: a measuring unit having an organic substance oxidation part for oxidizing organic substances contained in a supplied water sample to carbon dioxide by irradiation with UV light, a carbon dioxide separation part having a water sample channel through which a water sample transferred from the organic substance oxidation part flows and a measurement water channel through which measurement water constituted from deionized water flows, the carbon dioxide separation part being formed by integrating the water sample channel and the measurement water channel being in contact with each other gas-permeably and laminated in this order from top to bottom, and a conductivity measuring part for measuring a conductivity of the measurement water transferred from the carbon dioxide separation part, the measuring unit being formed by laminating the organic substance oxidation part, the carbon dioxide separation part, and the conductivity measuring part in this order from top to bottom, wherein an intensity distribution of the UV light for irradiating the water sample is non-uniform in a flow channel of the organic substance oxidation part resulting in a non-uniform distribution of the carbon dioxide in the water sample in the flow channel irradiated by the UV light; a control unit for controlling the operation of liquid delivery in the measuring unit; and a data processing unit for determining a concentration of total organic carbon from a conductivity of measurement water, the method comprising the steps of: controlling step by the control unit to stop feeding the water sample during oxidation of organic substances and to perform feeding the water sample when the water sample is moved to the carbon dioxide separation part through the organic substance oxidation part, wherein the water sample irradiated with the UV light has a portion irradiated with the UV light of which relative intensity is equal to or higher than a certain value and the other portion irradiated with the UV light of which relative intensity is lower than the certain value by the oxidation during the stop feeding the water sample, and data processing step by the data processing unit to determine the concentration of total organic carbon based on the conductivity measured when the portion of the water sample irradiated with the UV light of which relative intensity is equal to or higher than the certain value is flowing through the carbon dioxide separation unit.