Gas purifiers are necessary because they help in providing a clean gas stream, which can guarantee the grade of the gas chromatographic analysis and the reliability of the results. Further, such gas purifiers minimize detector noise and prolong the life span of the column. Gas purifiers are like plans to safeguard the instrumentation and other analytical columns from several types of contaminants. Still, the gas purifiers will not be in a position to convert low purity gases into high purity gases. Because of this important factor, it is necessary to select the proper grade of gases with different purity levels for proper used in gas chromatographic applications.
Selection of Right Gas Purifier to fit your Applications
Numerous kinds of gas purifiers can be found in the market. While some gas purifiers remove just one single specific contaminant, other styles remove multiple contaminants simultaneously from the gas stream. You have to think about several factors during the selection procedure for gas purifiers, taking into consideration your unique applications. headspace sampler will include the potential contaminants present in the gas stream, the limitations on flow and pressure, degrees of gas purity required, desired convenience in replacement of spent gas traps, and space availability.
Common Traps Found in Gas Purifiers
Oxygen, hydrocarbon, skin tightening and, and moisture traps will be the most common purifiers used in most the gas chromatography (GC) applications. Oxygen traps are usually filled with metal catalysts. Oxygen is recognized as probably the most detrimental contaminating gas in all analytical columns. Oxygen is with the capacity of producing irreversible oxidation damage, especially to polar stationary phases. Hydrocarbon traps are typically filled with activated charcoal, that may absorb organic compounds that are larger than methane. Still, the molecular weight and size of the organic contaminants will have a definite effect on the capacity of the hydrocarbon trap to an excellent extent but it will also reflect on trap efficiency somewhat.
Activated charcoal possesses a higher capacity to trap larger hydrocarbons which are greater than C4, compared to smaller hydrocarbons, which are lesser than C4. Moisture traps are usually filled with unique molecular sieves. When put through 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 can fit the cavity. Water fits perfectly into this cavity but this trap will also be able to remove gases like skin tightening and, sulfur dioxide, hydrogen chloride, and chlorine or other gases which have effective diameters lesser than water.
Procedure for Contaminants Affecting Gas Stream
If you want to understand how the contaminants affect the gas stream, you must follow the road that the carrier gas takes to find yourself in the gas chromatograph. This path does apply for detector fuel gases also. The gases start from a gas tank or a special gas generator. The gas travels through long lengths of tubes, pressure gauges, valves, and different other fittings. Each one of these areas is really a potential culprit to introduce contaminants into the gas stream. This leads not only in degrading the results of chromatography but also shortens the life 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 if they are exposed to oxygen or moisture, especially at high temperatures. These contaminants may also compromise detector performance. Since the detectors actually ‘see’ these contaminants, the effect is baseline noises, spikes, and drifts.
You should install gas purifiers in a vertical position as wall mounted types to prevent channeling. Channeling occurs when you install the gas purifier in a horizontal position. Gas purifiers can be found as compact panels having multiple purifiers or single panel that has multi-absorbent capabilities.
