논문 상세보기
pp.24-31
Purpose of CH4 reference gases Intercomparison is to evaluate measurement ability among different laboratories and to improve problems in analyzing reference gases. As a result, the goal is for being reached a scale within the limits of the possibility in intercomparison. Korea Meteorological Administration (KMA) and Korea Research Institute of Standards and Science (KRISS) carried out CH4 reference gases intercomparison of the Far East Asia managed by Japan and CH4 intercomparison among standard institutions managed by Consultative Committee for Amount of Substance (CCQM) respectively. CH4 reference gas and standard gases is injected to calibrate instrument drift by turns and checked uncertainty of measurement additionally. Expanded uncertainty in intercomparison among meteorological administrations in the Far East Asia showed 1784.3 ppb±0.26%, 1935 ppb±0.29% respectively. Expanded uncertainty in the case of one point calibration and multipoint calibration showed 1903 ppb±0.11%, 1904 ppb±0.32% respectively. One point calibration obtained better result than mult-point calibration because of having an extent of different manufacturing uncertainty in the case of using various standard gases and having an instrument drift caused by long-time analysis. Through these intercomparison experiment, we could know that concentration of CH4 standard gases produced in CMDL was higher about 1.3~1.4% (about 24~26 ppb) than those of KRISS. This is reason caused a difference between manufactured by gravimetric method and manometric method. Therefore, the standard gases is required to intervalidation with standard institutions and GAW observatories. Also, a low level standard gases need to be calibrated by upper level standard gases periodically.
