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Guard column or Retention gap?

Retention gaps are mainly used for focusing the sample components when introducing a large liquid sample directly on to the column. Guard columns, however, are used to protect the analytical column from contamination. When using a retention gap system, the gap will also act as a guard column, but its primary function is to create a focusing effect.

The guard column or the retention gap must be coupled to the analytical column, which may introduce a potential risk in many labs. But a new approach has been launched where the guard column is integrated with the analytical column. By applying a “segment”-coating technology, the stationary phase can be deposited in a certain part of the column, allowing for a deactivated section at the beginning. Column coupling is no longer required and maintenance is greatly simplified.

Please contact us for more information on our MEGA-GAP columns line with integrated built-in retention gap.


MEGA Retention gaps

- Retention gap DPTMDS: deactivated for General Purposes

- Retention gap HMDS: deactivated for Apolar Solvents Injections

- Retention gap CARBOWAX: deactivated for Polar Solvents Injections

Retention gaps are available with L = 1m, 2m, 5m, 10m 20m or 50m, ID = 0.25mm, 0.32mm or 0.53mm.


MEGA Press-Fit connectors

In modern gas chromatography the need to join two lengths of capillary column together in a leak-free, zero dead volume connection can arise in a variety of situations. Whether just repairing a broken column, adding a guard column or splitting column effluent 2 or 3 ways, press-fit glass (quartz) connectors are one route to a quick, effective and low cost solution.
The connectors work by having a gently tapered inner profile at each connection point that grips the cut end of column. On heating the connection in the GC oven, the polyimide coating of the column melts, bonding the column to the connector in a circular seal at this contact point to make the connection permanent.
In order for a leak-free connection to be made, it is essential that the capillary column has a perfect perpendicular cut at the end. Any jagged spurs, cracks or chips around the column end will provide a site for leakage. The cut may either be hand-prepared or cut using one of several custom-made tools designed for the purpose, but the end result must be the same: a smooth, perpendicular cut, free of jagged edges.


A002 The Retention Gap Effect
B009 Guide to the Use of PRESS-FIT Connectors