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 insurance policies to protect the instrumentation along with 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’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
Numerous kinds of gas purifiers can be purchased in the market. Although some gas purifiers remove just one single specific contaminant, other styles remove multiple contaminants simultaneously from the gas stream. You must think about several factors through the selection procedure for gas purifiers, taking into consideration your specific 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 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 usually filled with activated charcoal, which can absorb organic compounds that are bigger 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 a great extent but it may also think about 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 filled with unique molecular sieves. When put through extensive heating, the crystalline structures are forced to reduce 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.
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 find yourself in the gas chromatograph. This path is applicable for detector fuel gases also. headspace sampler 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 a potential culprit to introduce contaminants into the gas stream. This leads not only in degrading the outcomes 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 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 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 when 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.