SummarySupercritical carbon dioxide can be utilized both as an introduction solvent in capillary SFC and as a reaction medium; both possibilities are illustrated in this study. An off-line SFE unit was modified for on-line SFE-SFC. To facilitate rapid depressurization of the extraction cell and to prevent memory effects, a 6-port valve was installed at the outlet line of the extraction unit. An increased background signal was obtained when PEEK polymer was used in the construction of the extraction vessel; when stainless steel was used, the blanks improved. The synthesis of methyl esters and butyl esters of fatty acids from triglycerides in edible fat was examined using an immobilized lipase as a catalyst in on-line SFE-SFC. As a result of 30 minutes reaction -extraction time, high yields of fatty acid esters were obtained at a pressure of 150 bar and a temperature of 50°C.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.