Introduction

The term 'headspace analysis' was first applied to the analysis of gases in sealed cans and was later applied to the general analysis of vapours in contact with the sample from which they come. Gas chromatography was the technique of choice for this type of analysis; the combination is therefore called headspace-gas chromatography (HS-GC).

For quantitative analysis calibration of the volatiles in the vapour is necessary. This is achieved preferably, but not necessarily, in a state of equilibrium. To reach this state the sample is placed in a glass vial and thermostatted. When equilibrium is achieved, an aliquot of the gas phase above the sample is rapidly transferred onto the GC column. The term equilibrium HS-GC is commonly used for this sampling technique. However, since under certain circumstances calibration for quantitative analysis may also be performed in a nonequilibrium system, the term static HS-GC is more appropriate to distinguish this sampling technique from the so-called dynamic HS-GC techniques. In dynamic HS-GC analysis, the volatile compounds are stripped off completely from the sample by a continuous flow of an inert gas. This takes some time and the continuously delivered volatiles need to be concentrated in a trap, either by absorption or by cold trapping. The trapped compounds are released from the trap by thermal desorption and transferred to the gas chromatograph. This

See also: II/Chromatography: Gas: Column Technology; Detectors: General (Flame Ionization Detectors and Thermal Conductivity Detectors); Historical Development; Theory of Gas Chromatography. III/Gas Analysis: Gas Chromatography.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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