Gas purifiers are essential because they help in providing a clean gas stream, that may 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 span of the column. Gas purifiers are like plans to safeguard the instrumentation along with other analytical columns from various kinds of contaminants. Still, the gas purifiers will not be able to convert low purity gases into high purity gases. For this reason important factor, it’s important to select the right grade of gases with different purity levels for proper used in gas chromatographic applications.

Selection of Right Gas Purifier to fit your Applications

Various types of gas purifiers are available in the market. Although some gas purifiers remove just one specific contaminant, other types remove multiple contaminants simultaneously from the gas stream. You will need to reflect on several factors through the selection procedure for gas purifiers, considering your unique applications. These factors includes 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, 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 probably the most detrimental contaminating gas in every analytical columns. Oxygen is capable of producing irreversible oxidation damage, especially to polar stationary phases. Hydrocarbon traps are usually filled with activated charcoal, which can absorb organic compounds which are bigger than methane. Still, the molecular weight and size of the organic contaminants will have a definite effect on the capability of the hydrocarbon trap to a great extent but it may also reflect on trap efficiency to some extent.

Activated charcoal possesses an increased 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 headspace sampler , 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 able to remove gases like skin tightening and, sulfur dioxide, hydrogen chloride, and chlorine or other gases that 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 does apply for detector fuel gases also. The gases begin from a gas tank or 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 really a potential culprit to introduce contaminants into the gas stream. This leads not only in degrading the outcomes of chromatography but also shortens the life of the column of CG.

Major contaminants like oxygen, hydrocarbons, and moisture are capable of wreaking havoc with the columns and detectors of CG. The packed and capillary columns will get degraded easily if 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.

It is advisable to install gas purifiers in a vertical position as wall mounted types to prevent channeling. Channeling occurs once you install the gas purifier in a horizontal position. Gas purifiers can be found as compact panels having multiple purifiers or single panel which has multi-absorbent capabilities.