Gas purifiers are essential because they assist in providing a clean gas stream, which can guarantee the quality of the gas chromatographic analysis and the reliability of the results. Further, such gas purifiers minimize detector noise and prolong the life of the column. Gas purifiers are like insurance policies to safeguard the instrumentation along with other analytical columns from various kinds 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 right grade of gases with different purity levels for proper use in gas chromatographic applications.
Collection of Right Gas Purifier to Suit Your Applications
Various types of gas purifiers are available in the market. While some gas purifiers remove just one specific contaminant, other types remove multiple contaminants simultaneously from the gas stream. headspace sampler must think about several factors through 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, degrees of gas purity required, desired convenience in replacement of spent gas traps, and space availability.
Common Traps Used in Gas Purifiers
Oxygen, hydrocarbon, skin tightening and, and moisture traps are the most common purifiers found in majority of the gas chromatography (GC) applications. Oxygen traps are usually packed 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 packed with activated charcoal, that may absorb organic compounds which are larger 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 that are greater than C4, compared to smaller hydrocarbons, which are lesser than C4. Moisture traps are usually packed 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 can fit the cavity. Water fits perfectly into this cavity but this trap may also be able to remove gases like carbon dioxide, sulfur dioxide, hydrogen chloride, and chlorine or other gases that have effective diameters lesser than water.
Process of Contaminants Affecting Gas Stream
If you wish to understand how the contaminants affect the gas stream, you have to follow the road 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 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 additionally 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 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 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 can be found as compact panels having multiple purifiers or single panel that has multi-absorbent capabilities.