Preparation of Carbon Monoxide in Synthetic Air at Ambient Level by Gravimetric Method and High Accuracy Determination by Gas Chromatography

摘要

The atmospheric lifetime of CO varies from weeks to months depending on OH radical concentrations. CO itself does not directly contribute to the greenhouse effect, but the reaction of OH radical with CO controls the concentration distribution and variation in space and time of the other greenhouse gases such as CO_2, CH_4, O_3 etc. And then it will impact on regional environment and global climate. Ambient CO ranges from 50 nmol/mol to 300 nmol/mol at marine boundary, from 100 nmol/mol to 500 nmol/mol at city area. The World Meteorological Organization (WMO) requires exact analysis of CO at ambient level as 2% uncertainty. In this paper CO in synthetic air with the concentration level of 350 nmol/mol was prepared by gravimetric method and standard uncertainty was less than 0.3%. By using gas chromatography with FID/Methanator the RSD of the peak area of CO was less than 0.2% through the optimization of gas chromatographic conditions. Our lab on behalf of China participated in the CCQM-K84 international comparison of CO and achieved good agreement with other national labs.