UNDERWATER NITROGEN MEASURING DEVICE

摘要

PROBLEM TO BE SOLVED: To convert entire nitrogen in a water solution sample to NO and to compensate for interference due to CO2 at the time of measurement by detecting NO and CO2 in a sample vaporization gas using an NO detection part and a CO2 detection part, calculating the amount of interference of CO2 for NO detection in the NO detection part based on the detection value of the CO2 detection part, and compensating for the NO detection value. SOLUTION: A water solution sample is poured into a reaction tube 4 and is brought into contact with a heated catalyst oxide for thermal decomposition and vaporization, and a nitrogen constituent in a sample is converted to NO and at the same time the nitrogen constituent is converted to CO2 . The sample gas is fed by a carrier gas and the concentration of CO2 is measured by an NDIR 8 at the CO2 detection part. A sample gas through the NDIR 8 is guided to a chemical emission type NO detection part 10, a chemical emission due to the reaction between NO and ozone is detected, and NO concentration is measured. The output of the NDIR 8 and the NO detection part 10 is amplified by an analog amplifier 12 and is converted to digital by an A/D converter 14. The amount of CO2 interference is calculated and compensated for based on CO2 measurement value according to the NDIR8 by a CPU 16.