Evaluation of solvent venting with a gas purge for the introduction of microliter sample volumes in supercritical fluid chromatography

Abstract

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.

Supercritical Fluid Chromatography and Extraction

“…Greibrokk et al have led in the development of solvent-venting injection for OT-SFC. Their techniques allow automated injections of microliter volumes ( − ). Cortes et al.…”

Separation and quantification of components of edible fat utilizing open tubular columns in SFC. Sample introduction by direct injection and SFE coupled on-line to SFC

“…During 5 rain of solvent venting at an oven temperature of 36 ~ most of the octanoic acid, the most volatile compound, was evaporated together with the sample solvent. Increased recovery of volatile components can be obtained during solvent venting using cryofocusing [7]. Despite the large volume of solvent injected, isomeric fatty acids differing by only one double bond were almost baseline separated (Figure 3).…”