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What is the difference between liquid chromatography and gas chromatography?

Time:2018/11/09   Pageviews:0    Share:
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First, the mobile phase is different: HPLC is the liquid mobile phase, and GC is the permanent gas as the mobile phase (usually called carrier gas).
Second, the injector is different: the high-performance liquid phase is a flat-headed injection needle, and the gas chromatograph is a pointed syringe.
Third, the column length is different:
(1) Gas chromatography columns are 1.5ml gas chromatography vials usually several meters to several tens of meters.
(Gas chromatography has a low relative molecular weight and a large molecular gap, so the viscosity is low, the fluidity is good, and the components flow fast in the gas phase, so the column length can be increased to improve the column efficiency).
(2) The liquid chromatography column is usually several tens to several hundreds of millimeters.

Fourth, there are differences in the types of analysis:
Most of the objects analyzed by gas chromatography are (not absolutely): compounds with a molecular mass of less than 1000, low boiling point, volatile, and good thermal stability.
Liquid Chromatography: It is more suitable for the analysis of liquid compounds with high boiling point, difficult to volatilize, poor thermal stability and large molecular mass (1000 - -2000).
V: The change in the sample before the column is different: the sample of the gas chromatograph must be changed to gas before the column (vaporization of the gasification chamber), while the sample of the liquid chromatography does not change before the column.
Sixth, the detector used is different:
The liquid phase is mainly: ultraviolet detector, fluorescence detector, and refractive index detector.
 The main gas chromatographs are: 1.5ml gas chromatography vials hydrogen flame ionization detector (FID), thermal conductivity detector (TCD), electron capture detector (ECD), flame photometric detector (FPD), nitrogen phosphorus detector (NPD).

This is the end of the introduction of What is the difference between liquid chromatography and gas chromatography? I hope it can help you.


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