USE OF AN OPEN-TUBULAR TRAPPING COLUMN AS PHASE-SWITCHING INTERFACE IN ONLINE COUPLED REVERSED-PHASE LIQUID-CHROMATOGRAPHY CAPILLARY GAS-CHROMATOGRAPHY

The applicability of open-tubular traps for phase switching in coupled RPLC-GC was studied. The phase-switching process involves sorption of the analytes of interest from a methanol-water mobile phase into the stationary phase of an open-tubular column, removal of the aqueous phase by purging the trap with nitrogen and desorption of the analytes with hexane. Water elimination carried out in this manner appears to be highly efficient. In the sorption step the sampling flow-rate and the capacity factors of the analytes in the trap are critical parameters. Using a 2 m x 0.32 mm I.D. trap with a swollen 5-mum stationary phase at flow-rates not exceeding 100 mul/min, polycyclic aromatic hydrocarbons are trapped quantitatively from 300 mul of aqueous phases containing up to 65% (v/v) of methanol. For desorption 70-125 mul of hexane are needed. These volumes are easy to handle in solvent elimination carried out using a PTV injector prior to transfer of the analytes to a GC column.