ANALYSIS OF GASES ARTICLE SERIES
Analysis of Gases via Gas Chromatography
Part 1: Nitrous Oxide

by Jaap de Zeeuw (Restek, The Netherlands)

Article1.pngGas chromatography (GC) is a technique that deals with gas separations. Practically the components to separate must be brought in the gaseous phase to be able to be transported by the carrier gas. In order to do that, the temperature of the sample and column can be increased. Today’s gas chromatographs can be used up to 500 °C, meaning that it is possible to analyse components with boiling points around 700 °C. The component must be thermally stable. This works fine for hydrocarbons but more polar molecules will decompose.

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Analysis of Gases via Gas Chromatography
Part 2: Sulfur Gases

by Jaap de Zeeuw (Restek, The Netherlands)

Article1.pngSulfur components are widely present in many raw materials used for hydrocarbon processing. The sulfur components are undesirable because they have a strong smell, they cause acidic rain, they poison (expensive) catalysts and reduce polymer yields. Most problematic sulfur gases are hydrogen sulfide (H2S), carbonyl sulfide (COS) and methyl-ethyl mercaptans. These compounds have to be measured at ppb levels. Besides that sulfur gases are volatile, they are also very reactive. Systems for trace sulfur analysis must be very inert from the sampling device to GC setup to measure reproducible values at ppb levels.

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Analysis of Gases via Gas Chromatography
Part 3: CO and CO2

by Jaap de Zeeuw (Restek, The Netherlands)

Article1.pngCO and CO2 are products that are present in many industrial processes. CO2 is used in many applications varying from propellants, refrigerants, preservatives, beverages, inert atmosphere and fire extinguishers. It’s also used in oil recovery, supercritical solvent and in greenhouse. Carbon dioxide is analysed typically at higher levels (10 ppm – % level). CO is a toxic gas but it is mostly used as chemical precursor. Both CO and CO2 are analysed at levels from 100 ppb to % level. Because these gases cannot be detected by FID, other detectors are required. One can also convert the CO/CO2 into methane to take advantage of FID sensitivity.

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Analysis of Gases via Gas Chromatography
Part 4: Permanent and Noble Gases

by Jaap de Zeeuw (Restek, The Netherlands)

Article1.pngIn Part 3 of this series, we discussed the analysis of CO and CO2. Often a series of other gases has to be quantified. We will look here at hydrogen, oxygen, nitrogen, methane and the noble gases helium, neon, argon, xenon and krypton.

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