Optimisation of trapping parameters in preparative capillary gas chromatography for the application in effect-directed analysis.

Preparative capillary gas chromatography (pcGC) provides novel high resolution fractionation opportunities in effect-directed analysis. However, harvesting efficiency strongly depends on the operating parameters of the system. Therefore, the performance of the pcGC system was optimised by identifying the best operating parameters for the preparative fraction collector (PFC) using six test analytes with different physicochemical properties. The present study indicates that pcGC parameters need to be selected individually for the investigated analytes. The major focus was put on the trapping parameters as published findings on optimum trapping conditions are very variable. No generally agreed concept is available. An alternative to temperature-controlled trapping are solvent-filled traps. The solvent dichloromethane (DCM) proved to be most suitable for a large range of compounds. Recoveries are equal to optimised dry trapping at defined temperature. Optimised recoveries were in the range of 50-70% for all compounds except benzo[a]pyrene with a recovery of 94% using one PFC and DCM-filled traps at trapping temperature of -10 degrees C, at PFC temperatures of 300 degrees C for phenol, 400 degrees C for benzo[a]pyrene and 320 degrees C for the remaining analytes.