Headspace Sampler Awards: 9 Reasons Why They Don’t Work & What You Can Do About It
Gas purifiers are necessary 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 protect the instrumentation and other analytical columns from various kinds of contaminants. Still, the gas purifiers will never be in a position to convert low purity gases into high purity gases. Because of this important factor, it’s important to select the proper grade of gases with different purity levels for proper use in gas chromatographic applications.
Collection of Right Gas Purifier to fit your Applications
Various types 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 will need to reflect on several factors during the selection process of gas purifiers, considering your specific 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, 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 probably the most detrimental contaminating gas in all analytical columns. Oxygen is capable of producing irreversible oxidation damage, especially to polar stationary phases. headspace sampler are usually filled 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 think about trap efficiency somewhat.
Activated charcoal possesses an increased capacity to trap larger hydrocarbons which are greater than C4, in comparison to smaller hydrocarbons, which are lesser than C4. Moisture traps are usually packed 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 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 want to know how the contaminants affect the gas stream, you need 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 a special gas generator. The gas travels through long lengths of tubes, pressure gauges, valves, and different other fittings. Each 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 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.