In a packed column, the carrier gas percolates through the porous bed and separation is achieved by moving the solutes apart. Packed columns are made up of two main materials; stainless steel and Pyrex glass. Pyrex glass columns are shaped as desired by coiling at about 700°C. Glass column are in some cases treated with silanizing reagent to eliminate the surface hydroxyl groups which becomes catalytically active and produce asymmetric peaks. Chromosorb W is a fragile white solid prepared by heating the diatomaceous earth with a flux. The resulting fine structure is the cemented over glass which results in large and irregular pores. HP is the classification of a support as high performance grade.
Use a glass column for applications where high inertness is required, such as for the analysis of active analytes. All glass columns undergo a proprietary high temperature silanization to ensure inertness. This column fits Agilent 5880, 5890, 6890. 7820, and 7890 (configuration A, on-column injection, all detectors except TCD).