Gas purifiers are essential because they assist in providing a clean gas stream, that may guarantee the quality 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 plans to safeguard the instrumentation and other analytical columns from several types of contaminants. Still, the gas purifiers will never be able to convert low purity gases into high purity gases. Due to this important factor, it is necessary 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 are available in the market. While some gas purifiers remove just one single specific contaminant, other types remove multiple contaminants simultaneously from the gas stream. You will need to reflect on several factors during the selection procedure for gas purifiers, taking into consideration your unique applications. These factors includes the potential contaminants present in the gas stream, the limitations on flow and pressure, levels 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 found in majority of the gas chromatography (GC) applications. Oxygen traps are normally packed with metal catalysts. Oxygen is considered 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 bigger than methane. Still, the molecular weight and size of the organic contaminants will have a definite influence on the capability of the hydrocarbon trap to a great extent but it will also think about trap efficiency to some extent.
Activated charcoal possesses a higher 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 in a position 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 will need to follow the road that the carrier gas takes to get into the gas chromatograph. headspace sampler 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 in to 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 are capable of wreaking havoc with the columns and detectors of CG. The packed and capillary columns can get degraded easily if they face oxygen or moisture, especially at high temperatures. These contaminants will also compromise detector performance. Because 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 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.