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Advantages And Disadvantages Of Gas Chromatography

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Gas chromatography is one of the chromatographic technique which is extensively used in revealing organic compounds. In gas chromatography, the compounds to be analyzed are vapourized and eluted through a column with the help of a gas as the mobile phase. The mobile phase is used exclusively as a carrier gas, so that interactions of the mobile phase with the analyte are negligible. Apart from that, the stationary phase can be either a solid or liquid.
A solid substance can act as a stationary phase on which the constituents to be separated can be adsorbed. In practice, gas-solid chromatography (GSC) or adsorption chromatography is essential for the analysis of air gases. The use of liquid as stationary phase is preponderant for the analysis …show more content…

Yet, GC still plays an critical role in certain types of quantitative analysis and has broad application in qualitative analysis. The advantages of GC may be overlooked since HPLC is dictating the quantitative analysis in pharmaceutical industry nowadays. Capillary GC is capable of performing much more effective separations than HPLC with the limitation that the compounds being analyzed must be volatile or must be rendered volatile by formation of suitable derivative and must also be thermally stable. GC is widely used in environmental science, brewing, the food industry, perfumery and flavouring analysis, the petrochemical industry, microbiological analyses and clinical biochemistry. …show more content…

Habitually, the injected sample first goes into the inlet/inlet liner and is carried by the carrier gas to the column. The sample injection port, column, and detector are heated to temperatures at which the sample has a vapor pressure of at least 10torr, usually about 50◦C above the boiling point of the highest boiling solute. The injection port and detector are generally kept warmer than the column to vaporize the injected sample quickly and prevent the condensation of sample in the detector. For packed columns, liquid samples of 0.1 to 10 μL are injected, while gas samples of 1 to 10mL are injected. Gases may be injected via a gas-tight syringe or through a special gas inlet chamber of constant volume (gas sampling valve). For capillary columns, sample consisting of volumes of only about 1/100 these sizes must be injected due to the lower capacity (albeit greater resolution) of the columns. Sample splitters are incorporated on chromatographs designed for use with capillary columns that deliver a small fixed fraction of the sample to the column, with the remainder going to waste.

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