Improved quantitative capillary GC by the use of CO2 as secondary coolant in cold on-column injection

A comparison is made between air and carbon dioxide as secondary cooling gases in cold on-column injection into capillary columns. Because CO₂ is a more effective coolant than air, the injection zone can be kept at a colder temperature, thus preventing loss of sample vapor through the open injector even as the initial oven temperatures because greater than the boiling point of the solvent. Sample loss at these elevated temperatures is shown as a reduction in peak area as functions of column temperature during injection and different injection zone temperatures. The maximum allowable oven temperature during injection is significantly higher when CO₂ is used as secondary coolant rather than air.