中文摘要 一氧化碳是燃燒以及大氣光化之產物，可借其背景濃度變化反推大氣氧化的能力，同時它也是高毒性的污染氣體。本研究利用小孔徑分子篩當作填充靜相做為一氧化碳分子的層析管柱，並由鎳觸媒管將一氧化碳還原成甲烷，再搭配感度、線性皆相當良好的火焰離子偵檢器(FID：flame ionization detector)做偵測，開發低成本的自製分析系統。方法驗証上分別與現行環保單位廣泛應用的非分散式紅外線光譜儀(non-dispersive IR)以及美國背景測站所使用的汞還原分析儀做一連續性的平行比對，以達到充份驗證的目的。 而後針對上述系統的缺點做進一步的改良，利用雙管柱逆吹的層析方法以恆溫方式分析，縮短分析時間增加並時間解析上的能力，藉此更精確的描繪一氧化碳的濃度變化，並改善長期觀測上因管柱調理所可能產生的不穩定因素。 再者，希望開發中孔徑的矽分子篩材料在層析技術上的應用。利用具有較大孔徑的持性，預期能夠作為快速分離大氣中的二氧化碳的填充靜相，並且搭配已經建構完成的自動進樣系統以及熱導偵檢器(thermal conductivity detector)，探討新材料在應用上的可能性，最後並設計簡單的動態稀釋裝置，用以產生不同濃度之CO2氣體當作初步的定性依據；並根據不同的稀釋比例，驗証分析效果的線性以及再現性。 Abstract Carbon monoxide is a by-product of biomass burning and photochemistry in the atmosphere. Monitoring background CO is a means to indirectly diagnose atmospheric oxidation capacity. The first part of this study involves the development of an automated gas chromatographic system for CO analysis. Using a molecular sieve 5Å column and a flame ionization detector (FID) with a Ni catalyst, CO can be reduced to CH4 by feeding H2 and detected by FID. The completed system was validated by a NDIR CO analyzer and a Reduced Gas Analyzer (RGA) by synchronously monitoring the CO variation in ambient air. The GC/FID/methanizer system was further modified into a back-flash model, which was able to perform CO monitoring with improved precision and better consistency with NDIR and RGA, because the separation can then be run at isothermal condition resulting in better analytical stability. Furthermore, this research also assessed the feasibility of employing mesoporous silica, i.e., MCM-41, MCM-48, and SBA-15, as the potential stationary phases aiming at separating CO2 in the atmosphere. By devising a similar system to that for CO with a thermal conductivity detector (TCD), it was found that MCM-41 with pore size of 46.6Å allowed the best CO2 separation. CO2 can be eluted from the MCM-41 packed column with a symmetric peak shape and within a reasonable time spent of 8 minutes . Due to the poor sensitivity of the TCD, a simple dynamic dilution device was built to easily make CO standards of any desired concentrations for testing the separation effectiveness and quality control aspects such as precision and linearity.
