Partially concurrent eluent evaporation

While partially concurrent eluent evaporation is easier to use, and is preferred for the transfer of normal phase solvents, concurrent eluent evaporation with co-solvent trapping is the technique of choice for transfer of water-containing solvents, because wettability is not required. 

M. Biedermann, K. Grob and W. Meier, Partially concurrent eluent evaporation with an early vapor exit detection of food irradiation through coupled LC-GC analysis of the fat , /. High Resolut. Chromatogr. 12 591-598 (1989). 

Retention gap techniques with on-column interfaces are used to analyze those analytes that are poorly retained during full concurrent eluent evaporation [98-102,105]. The eluent fraction is pushed by the liquid chromatography pump into the thermostatted retention gap where it is mixed with carrier gas and evaporated at a temperature below the pressure corrected eluent boiling point. A layer of condensed solvent (flooded zone) is formed in front of the evaporation site that acts as a temporary retaining liquid phase. Partial concurrent eluent evaporation during transfer allows the use of shorter retention gaps and an increase in the eluent volume that can be transferred. A 10 m x 0.53 mm... 

For the highly volatile components, commonly present in essential oils, the most adequate transfer technique is partially concurrent eluent evaporation [137]. In the latter technique, proposed by Grob, a retention gap is installed, followed by a few meters of precolumn and the analytical capillary GC column, both with identical stationary phase, for the separation of the LC fractionated components. A vapor exit is placed between the precolumn and the analytical column, allowing partial evaporation of the solvent. Hence, column and detector overloading are avoided. This transfer technique can be applied to the analysis of GC components with a boiling point of at least 50°C higher than the solvent. 

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