The gas chromatograph detector has different response values ​​to different substances, and the absolute/relative correction factor of the measured substance is the basis for accurate quantification. How to determine the relative correction factor of a substance when using TCD as a detector?

When using TCD as a detector, there are usually several ways to determine the relative correction factor for a substance.

1. Find relative correction factors from the literature

For conventional components, it can usually be found in chromatography related books or literature. For the thermal conductivity detector, the commonly used standard is benzene, and the carrier gas used is helium or hydrogen.

2. Experimental determination of relative correction factors

For some of the more specific substances that do not have a relative correction factor in the literature or to more accurately determine the correction factor for a substance, it is usually obtained by experimental determination. However, when using the experimental method to determine the relative correction factor of the substance, attention should be paid to the accuracy of the configuration standard. Otherwise, there will be a case where the correction factor measured by the test differs greatly from the literature value.

The relative correction factors measured by some analysts are inconsistent with the literature values, not caused by fluctuations in operating parameters, but due to measurement errors, such as insufficient purity of standards, improper preparation of samples, volatilization of components at room temperature, and inaccurate measurement of peak area. The peaks obtained are very asymmetrical or incompletely separated. For the analysis of volatile components, the effect of sample preparation is particularly significant.

3. Estimate the correction factor using the law

Currently, only the thermal conductivity detector and the hydrogen flame ion detector for the gas chromatograph can be used to estimate the correction factor. When no suitable data can be found in the literature and no known standard content is measured, it can be estimated according to the method described in the relevant reference book, as the relative molar response of the structure on the thermal conductivity detector and its molecular The carbon number or molar mass in the linear relationship is linear. However, this method is not widely used in practical operations.

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Label: How to determine the relative correction factor of a substance when analyzing gas chromatograph

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