Guard columns and retention gaps are used widely in gas chromatography. Both of them are short (1-10 m) piece of uncoated deactivated fused silica tubing which are placed in-line between the
GC injection port and the analytical capillary column. Guard column is to protect the analytical column from contamination, not allowing nonvolatile materials to reach the analytical column. Retention gap is to help focus the compounds in large volume injected from the inlet to a small band at the head of the analytical column. InertCap ProGuard is a"guard column built-in"analytical capillary column without the connection for such purposes. For this reason, now there is no need to worry about leakage and compounds adsorption.