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High performance reversed-phase chromatography (HPRC) is an efficient and powerful tool gaining momentum in the separation of triglycerides and other lipid components. In the present study the effect of different variables in triglyceride separation has been studied. It was found that a longer hydrocarbon chain bonded to silica gel as well as the percent coverage improved the separation. Smaller particle size packing increased triglyceride resolution. A decrease in mobile phase polarity by increasing the acetone content resulted in a decrease in the retention time and resolution of triglyceride.

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The least stable thiophenes were 5-(but-3-ene-l-ynyl)-2,2'-bithiophene and 5-(but-3-ene-l-ynyl)-5'-methyl-2,2'-bithiophene. This lower stability is attributed to the molecules' highly conjugated side chains, which interact more strongly with the W A radiation; these side chains are absent in 2,2',5',2"-terthiophene and 5-methyl-2,2',5',2"-terthiophene. It is not clear whether other factors contribute to the increased stability.More than 35 % of 2,2',5',2"-terthiophene and 5-methyl-2,2',5', 2"-terthiophene was left in the flower oil after 24 h of exposure and it is thus surprising to find reports in the literature which claim that irradiated marigold extracts are not biocidal to mosquitoes IS]. A possible explanation is that the concentrations of 2.2',5',2"-terthiophene and 5-methyl-2,2'5',2"-terthiophene are below those required to elicit a biocidal response in mosquitoes. Current work focuses on the economical isolation of this group of insecticidal components.

Cholesterol and cholesteryl esters were separated according to their carbon number and number of double bonds by high performance reversed-phase chromatography (HPRC) using acetonitrile/chloroform/methanol (1:1:1, v/v) as a mobile phase. It was found that within the same equivalent carbon number (ECN) category, cholesteryl esters with the highest number of double bonds eluted ahead of those with a lower number of double bonds, and with the cis isomers eluting ahead of their trans partners. Thus, cholesteryl oleate (C27-18:1c) elutes ahead of cholesteryl palmitate (C27-16:0) and ahead of cholesteryl elaidate (C27-18:1t). Human lipoprotein, as well as rat liver cholesteryl esters, were separated using this technique.