INSERTS PROVIDING COMPLETE SAMPLE EVAPORATION ABOVE THE COLUMN ENTRANCE IN VAPORIZING GC INJECTORS

Completeness of sample evaporation in conventional vaporizing injectio n is a problem for many samples and calls for measures to arrest the s ample liquid in the space between the needle exit and the column entra nce. A visual testing procedure reveals that a small plug of loose gla ss or quartz wool ensures complete evaporation in all instances. Obsta cles built into the liner also stop liquid, provided they force the sa mple to pass through narrow channels. Other important design character istics concern access to the narrow channel. Evaporation in a packed i nsert usually occurs from a surface, whereas the sample hardly touches surfaces in the instance of an insert with obstacles. Evaporation fro m a packing is, in fact, more reliable, but creates more problems conc erning inertness.