Gas purifiers are necessary because they assist in providing a clean gas stream, that may guarantee the quality of the gas chromatographic analysis and the reliability of the outcomes. Further, such gas purifiers minimize detector noise and prolong the life span of the column. Gas purifiers are like plans to protect the instrumentation and other analytical columns from various kinds of contaminants. Still, the gas purifiers will never be in a position to convert low purity gases into high purity gases. Because of this important factor, it’s important to select the right grade of gases with different purity levels for proper use in gas chromatographic applications.
Collection of Right Gas Purifier to fit your Applications
Numerous kinds of gas purifiers can be purchased in the market. While some gas purifiers remove just one single specific contaminant, other types remove multiple contaminants simultaneously from the gas stream. You should reflect on several factors during the selection process of gas purifiers, taking into consideration your specific applications. These factors includes the potential contaminants within the gas stream, the limitations on flow and pressure, levels of gas purity required, desired convenience in replacement of spent gas traps, and space availability.
Common Traps Found in Gas Purifiers
Oxygen, hydrocarbon, carbon dioxide, and moisture traps will be the most common purifiers used in majority of the gas chromatography (GC) applications. Oxygen traps are usually packed with metal catalysts. Oxygen is considered as the most detrimental contaminating gas in every analytical columns. Oxygen is with the capacity of producing irreversible oxidation damage, especially to polar stationary phases. headspace sampler are usually filled with activated charcoal, which can absorb organic compounds that are larger than methane. Still, the molecular weight and size of the organic contaminants could have a definite effect on the capacity of the hydrocarbon trap to a great extent but it will also reflect on trap efficiency somewhat.
Activated charcoal possesses an increased capacity to trap larger hydrocarbons that are greater than C4, compared to smaller hydrocarbons, which are lesser than C4. Moisture traps are often filled with unique molecular sieves. When subjected to extensive heating, the crystalline structures are forced to lose their hydration or water content. This opens a cavity which gets filled readily with any compound that may fit the cavity. Water fits perfectly into this cavity but this trap will also be in a position to remove gases like carbon dioxide, sulfur dioxide, hydrogen chloride, and chlorine or other gases which have effective diameters lesser than water.
Procedure for Contaminants Affecting Gas Stream
If you wish to understand how the contaminants affect the gas stream, you will need to follow the path that the carrier gas takes to find yourself in the gas chromatograph. This path is applicable for detector fuel gases also. The gases start from a gas tank or perhaps a special gas generator. The gas travels through long lengths of tubes, pressure gauges, valves, and various other fittings. Every one of these areas is really a potential culprit to introduce contaminants in to the gas stream. This leads not merely in degrading the results of chromatography but also shortens the life span of the column of CG.
Major contaminants like oxygen, hydrocarbons, and moisture can handle wreaking havoc with the columns and detectors of CG. The packed and capillary columns can get degraded easily when they face oxygen or moisture, especially at high temperatures. These contaminants will also compromise detector performance. Because the detectors actually ‘see’ these contaminants, the result is baseline noises, spikes, and drifts.
You should install gas purifiers in a vertical position as wall mounted types to avoid channeling. Channeling occurs once you install the gas purifier in a horizontal position. Gas purifiers are available as compact panels having multiple purifiers or single panel which has multi-absorbent capabilities.