METHOD FOR MEASURING GAS CONCENTRATION

摘要

PROBLEM TO BE SOLVED: To develop a method capable of performing stable measurement for a long time by inhibiting the value of a current from lowering with the lapse of time in measuring the concentration of gaseous nitrogen oxide ion a measured gas by using a solid electrolyte type gaseous nitrogen oxide sensor. SOLUTION: This method uses the solid electrolyte type gaseous nitrogen oxide sensor made by forming a detection electrode layer and a counter electrode layer containing alkaline metal nitrate and/or alkaline metal nitrite, and a reference layer if necessary, on a surface of a solid electrolyte layer. A voltage is applied between the detection electrode layer and the counter electrode layer while they are heated up to 100 to 600 deg.C so that the detection electrode layer is at a potential lower than the counter electrode layer. The value of a current flowing across the two electrode layers is measured to measure the concentration of gaseous nitrogen oxide in the measured gas. The period during which the voltage is applied is established so that the counter electrode layer is at a potential lower than the detection electrode layer each time the measurement is carried out for a fixed period.