GIT&T: Optimization of Capillary Connections

Besides bringing many advantages, a reduction in the internal diameter is accompanied by certain complications.  The influence of dead volumes on the efficiency when using miniature columns is therefore very clear and should be avoided. One can achieve a lot by using the following tips and tricks for capillary connections.

 What does one need to consider with regard to the capillaries?

Independent of which kind of capillary is used, there are some general points that need to be considered when connecting the system components e.g. the detector and the column, if a high efficiency is to be achieved

  • Install capillaries without dead volumes.

This can be managed if the capillaries are flush with connector piece. Here, it can be helpful to use a light counter pressure in the screw connection. Another possibility for achieving a better result is if the capillaries are installed directly vertical to the connector piece as this prevents any shifting.     

  • It is of utmost importance that the capillaries being used have a clean, straight cut end. Figure 1 shows frequent mistakes but als0 the correct way to install capillaries.

What is the advantage?

Looking at Figure 2 it is clear that in a real live example, the peak’s form and therefore the quality of the connection have an influence on the number of buffer stages. The red line represents the Gaussian-fit and shows the deviation from the optimum peak form.    

It is quite clear that a reduction in the tailing factor from 1.25 to 1.12 has the effect of increasing the efficiency by ca. 550 floors. It is therefore recommended that when exchanging the columns one pays special attention to the connection capillaries.   

If you have questions about the application and technology in the field of Micro-LC and 2D-LC, ask the experts at IUTA: adlichrom@iuta.de

Author:

Denise Loeker, IUTA Duisburg

Contact

Microsite Advanced Liquid Chromatography


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