Abstract. The solvent venting injection technique has been tested for 1-pL injections of lipids in open tubular column SFC. No sample loss during solvent venting was experienced with a 7-m precolumn at elevated temperatures. The solvent venting technique has also been combined with gas purging to concentrate the sample on-line with SFC. Injections totalling 10-50 pL of sample have been performed. The solvent venting technique with minor modifications in the instrumentation was utilized for group separations of triglycerides. Different techniques for solute focusing were tested. The best peak shape was obtained by a combination of phase ratio and low temperature focusing.

Abstract. Peak broadening and sample recovery are important considerations when working with large sample volume injections in capillary SFC. To measure possible contribution to peak broadening in the venting valve, a tee coupling was inserted between the retention gap and the column. A standard sample containing glyceryl esters was injected. Based on time variance measurements, the venting valve did not lead to measurable band broadening. Recovery was found to be dependent on the length of the retention gap, the C02/He ratio in the purge gas, and the temperature of the retention gap. Cryofocusing was needed to increase the recoveries of volatile n-alkanes. To increase the recoveries of glyceryl esters, an enhanced C02/He ratio was needed.