Large volume splitless injection with concurrent solvent recondensation: Keeping the sample in place in the hot vaporizing chamber

Abstract

An injector liner packed with a plug of glass wool is compared with a laminar and a mini laminar liner for large volume (20-50 microL) splitless injection with concurrent solvent recondensation (CSR-LV splitless injection). Videos from experiments with perylene solutions injected into imitation injectors show that glass wool perfectly arrested the sample liquid and kept it in place until the solvent had evaporated. The sample must be transferred from the needle to the glass wool as a band, avoiding 'thermospraying' by partial solvent evaporation inside the needle. The liquid contacted the liner wall when the band was directed towards it, but from there it was largely diverted to the glass wool. In the laminar liners, part of the liquid remained and evaporated at the entrance of the obstacle, while the other proceeded to the center cavity. Vapors formed in the center cavity drove liquid from the entrance of the obstacle upwards, but the importance of such problems could not be verified in the real injector. Some liquid split into small droplets broke through the obstacle and entered the column. Breakthrough through the laminar liners was confirmed by a chromatographic experiment. An improved design of a laminar liner for large volume injection is discussed as a promising alternative if glass wool causes problems originating from insufficient inertness.