Medusa: A Sample Preconcentration and GC/MS Detector System for in Situ Measurements of Atmospheric Trace Halocarbons, Hydrocarbons, and Sulfur Compounds

详细信息    查看全文

• 作者：Benjamin R. Miller ; Ray F. Weiss ; Peter K. Salameh ; Toste Tanhua ; Brian R. Greally ; Jens Mü ; hle ; Peter G. Simmonds
• 刊名：Analytical Chemistry
• 出版年：2008
• 出版时间：March 1, 2008
• 年：2008
• 卷：80
• 期：5
• 页码：1536 - 1545
• 全文大小：299K
• 年卷期：v.80,no.5(March 1, 2008)
• ISSN：1520-6882

文摘

Significant changes have occurred in the anthropogenicemissions of many compounds related to the Kyoto andMontreal Protocols within the past 20 years and many oftheir atmospheric abundances have responded dramatically. Additionally, there are a number of related naturalcompounds with underdetermined source or sink budgets. A new instrument, Medusa, was developed to makethe high frequency in situ measurements required for thedetermination of the atmospheric lifetimes and emissionsof these compounds. This automated system measures awide range of halocarbons, hydrocarbons, and sulfurcompounds involved in ozone depletion and/or climateforcing, from the very volatile perfluorocarbons (PFCs,e.g., CF₄ and CF₃CF₃) and hydrofluorocarbons (HFCs,e.g., CH₃CF₃) to the higher-boiling point solvents (suchas CH₃CCl₃ and CCl₂=CCl₂) and CHBr₃. A network ofMedusa systems worldwide provides 12 in situ ambientair measurements per day of more than 38 compoundsof part per trillion mole fractions and precisions up to0.1% RSD at the five remote field stations operated bythe Advanced Global Atmospheric Gases Experiment(AGAGE). This custom system couples gas chromatography/mass spectrometry (GC/MSD) with a novel schemefor cryogen-free low-temperature preconcentration (-165C) of analytes from 2 L samples in a two-trap processusing HayeSep D adsorbent.