Special cooling system for the on-column injector in capillary gas chromatography eliminating discrimination of sample compounds



On-column injection into a hot gas chromatograph oven involves the danger that the bottom part of the needle is warmed up above the boiling point of the solvent in the sample. Consequently parts of the sample are evaporated out of the needle instead of being introduced as a liquid into the capillary column. This causes losses and hence discrimination of the less volatile parts of the sample which remain in the needle.

A technical solution is proposed using a system for cooling the capillary during the injection, down to the injection point in the oven.