BASE DEACTIVATED GUARD COLUMN
Proprietary deactivation of the tubing, suitable for analysis of amines and other basic compounds.
PURPOSE OF GUARD COLUMNS (RETENTION GAPS) A capillary guard column is a length of 1-10 meters of deactivated fused silica tubing attached to the front of the capillary column. Deactivated fused silica tubing does not contain any stationary phase, however, the surface is deactivated to minimize solute interactions.
The tubing is attached to the column with a suitable union or universal press fit connector. Usually the diameter of the guard column is the same as the analytical column. If the tubing sizes are different, it is better to have a larger diameter guard column than a smaller one. Guard columns trap non-volatile residues and prevents them from collecting on the inlet of the analytical column resulting in longer column life. This greatly reduces the interaction between the sample and the residues as the guard column does not retain the solutes (because it does not contain any stationary phase). Also, the residues do not coat the stationary phase which often results in poor peak shapes.
Periodically it is necessary to trim the guard column due to the build-up of residues. Guard columns of 5 to 10 meters allow for considerable trimming before it has to be replaced. Abnormal peak shapes usually indicates that the guard column requires trimming or changing. Various guard columns are available with different polarities. It is important to match the polarity of the solvent with the polarity of the surface deactivation.
More information is available in the Greyhound Q-Cap Capillary Columns catalogue
