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 outcomes. Further, such gas purifiers minimize detector noise and prolong the life of the column. Gas purifiers are like insurance policies to protect the instrumentation along with other analytical columns from different types of contaminants. Still, the gas purifiers will not be in a position to convert low purity gases into high purity gases. headspace sampler to this important factor, it’s important to select the proper grade of gases with different purity levels for proper use in gas chromatographic applications.

Selection of Right Gas Purifier to fit your Applications

Numerous kinds of gas purifiers can be purchased in the market. Although some gas purifiers remove just one specific contaminant, other types remove multiple contaminants simultaneously from the gas stream. You should think about several factors during the selection process of gas purifiers, taking into consideration your specific applications. These factors will include the potential contaminants within 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, carbon dioxide, and moisture traps are the most common purifiers found in most the gas chromatography (GC) applications. Oxygen traps are usually packed with metal catalysts. Oxygen is recognized as the most detrimental contaminating gas in all analytical columns. Oxygen is capable of producing irreversible oxidation damage, especially to polar stationary phases. Hydrocarbon traps are typically packed with activated charcoal, that may absorb organic compounds which are bigger than methane. Still, the molecular weight and size of the organic contaminants could have a definite influence on the capacity of the hydrocarbon trap to an excellent extent but it may also think about 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 often packed 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 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 should follow the path that the carrier gas takes to get into 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 different other fittings. Every one of these areas is 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 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 will get degraded easily when they face oxygen or moisture, especially at high temperatures. These contaminants will 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 are available as compact panels having multiple purifiers or single panel that has multi-absorbent capabilities.