In the process of using gas chromatography, partners often hear the word “solvent effect”. What exactly does “solvent effect” mean? About the solvent effect in gas chromatography, today will give you a brief overview and related solutions.
In gas chromatography, the boiling point of sample components is very important in the process of chromatographic separation. When we analyze some compounds with low boiling point, the peak time of sample components will be relatively shorter. Therefore, for these sample components with short peak time, they will overlap or cover the solvent peak in the sample solution. This phenomenon is the “solvent effect” in gas chromatography. So what are the reasons for this phenomenon and how to avoid “solvent effect” in the analysis process?

In the process of recording the chromatogram by the detector, when our solvent peak is seriously tailed and the peak width is large, it will be easier to affect the resolution with the target peak, so it is easier to cover some sample components that flow out earlier.

First of all, we need to understand the injection process of the gas chromatograph. Our sample will be injected into the injection port through the injection needle. Due to the high temperature of the injection port, the sample solution will vaporize. The volume of the sample solution vaporized at the sample inlet is much larger than the volume of the unit carrier gas flow rate set by us, so that the carrier gas can not concentrate the sample components into the chromatographic column quickly. The solvent in the sample solution is the largest component, which will cause a wide spectral band of the solvent peak in the chromatographic separation process, accompanied by serious tailing, and cover some early outflow sample components. In order to avoid solvent effect and improve the resolution between solvent peak and sample components, the following solutions are available:

When the sample capacity of the chromatographic column is relatively large: we can set the initial temperature to about 20 ℃ lower than the boiling point of the solvent by changing the heating program of the column temperature box. In this way, the vaporized sample solution will condense at the column head of the chromatographic column and the sample solution will be refocused; Then, in the next temperature programmed process, the condensed sample solution will gradually vaporize and enter the chromatographic column in turn for chromatographic separation. This focusing process is conducive to narrowing the peak width and increasing the peak height of our sample solvent peak; In this way, the resolution between the solvent peak and the target peak can be effectively improved without covering some early outflow sample components.

When the sample capacity of the chromatographic column is small: in order to avoid the overload of the chromatographic column and solve the solvent effect at the same time. We can also avoid solvent effect by changing the injection volume of sample solution. For example, adopt the split mode, increase the split ratio of gas chromatography, or select a smaller injection volume.

In addition, Welch Materials has focused on the R & D and production of gas chromatographic columns for many years, with the advantages of super inertia, low loss, high column efficiency and long life. In recent years, the technology has been launched in the medicinal herbs and herbal pieces (plant) banned pesticide multi residue determination, 22 kinds of organic chlorine, 37 kinds of fatty acids, liquor ingredient analysis and other popular applications. With excellent product performance and perfect customer service system, the company’s gas chromatography column has been widely applied in universities, research institutes, pharmaceutical, petrochemical, brewing, Environmental protection and other industries.

If you have any problem or require further information, please contact info@welchmat

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