A SIMPLE LARGE-VOLUME INJECTION SYSTEM WITH A SOLID-PHASE SAMPLE LOOP FOR PACKED-COLUMN SUPERCRITICAL-FLUID CHROMATOGRAPHY

The design and use of an easy-to-build large-volume injection system for packed column supercritical fluid chromatography (SFC) are reported. Two 6-port injection valves are used. After introduction of a liquid sample via the sample loop of one of the valves, nitrogen is used to transport the sample to a solid-phase extraction disk which is placed in a pressure tight fitting. The sample solvent evaporates into the nitrogen stream leaving the analytes on the solid-phase material. After a certain evaporation time the moblie phase of the SFC is directed to the solid phase, introducing the solvent-free sample into the SFC. It is possible to introduce liquid sample volumes of PAH- and PCB-solutions of up to 100 mu l without loss of chromatographic resolution. The relative standard deviations of peak areas are in the range of 4-9%.