Separation of Fatty Acid Dimethyl Esters on an Ionic Liquid Gas Chromatographic Column.

An ionic liquid (IL) 111 column was compared with other commonly employed stationary phases including polydimethyl siloxane and polyethylene glycol for the separation of fatty acid monomethyl and dimethyl esters. The fatty acid esters employed in this study were derived from metathesis reactions of vegetable oils both with and without olefins. The IL 111 column demonstrated enhanced performance compared with conventional columns for the separation of these esters. These advantages included significantly enhanced retention of dimethyl esters relative to monomethyl esters, excellent cis/trans isomer separation and the ability to analyze higher carbon number dimethyl esters. As a result, these columns are highly suited for the analysis of mixtures of mono- and dimethyl fatty acid esters found in lipid metathesis reaction products or to determine monofunctional impurities in samples of commercial dimethyl esters.

Fast gas chromatographic separation of biodiesel.

A high-speed gas chromatographic method has been developed to determine the FAME distribution of B100 biodiesel. The capillary column used in this work has dimensions of 20 m × 0.100 mm and is coated with a polyethylene glycol film. Analysis times are typically on the order of 4-5 min depending upon the composition of the B100. The application of this method to a variety of vegetable and animal derived B100 is demonstrated. Quantitative results obtained with this method were in close agreement with those obtained by a more conventional approach on a 100 m column. The method, coupled with solid-phase extraction, was also found suitable to determine the B100 content of biodiesel-diesel blends.

A review of chromatographic characterization techniques for biodiesel and biodiesel blends.

This review surveys chromatographic technology that has been applied to the characterization of biodiesel and its blends. Typically, biodiesel consists of fatty acid methyl esters produced by transesterification of plant or animal derived triacylglycerols. Primary attention is given to the determination of trace impurities in biodiesel, such as methanol, glycerol, mono-, di-, and triacylglycerols, and sterol glucosides. The determination of the fatty acid methyl esters, trace impurities in biodiesel, and the determination of the biodiesel content of commercial blends of biodiesel in conventional diesel are also addressed.

Determination of elemental sulfur in gasoline by gas chromatography with on-column injection and flame ionization detection following derivatization with triphenylphosphine.

Several years ago, the presence of elemental sulfur in gasoline became a significant issue for the automotive and fuel industries. In several incidents, elemental sulfur at trace levels led to the corrosion of silver alloy fuel sensing elements in automobile gasoline tanks. This report describes a derivatization method that allows the determination of trace levels of elemental sulfur using flame ionization detection. The sample is derivatized with triphenylphosphine to form triphenylphosphine sulfide. This component is readily detected with a flame ionization detector. In most analyses, on-column injection was employed to allow detection of trace levels of elemental sulfur. However some analyses with splitless injection were also performed. For some gasolines, detection limits on the order of less than 1 microg/g elemental sulfur were possible with this approach. However, the detection limit can vary depending upon the concentration of trace higher boiling components. The precision of the analysis, as measured by the relative standard deviation of triplicate injections, for gasolines containing 1 to 10 microg/g of elemental sulfur was in the 1 to 3% range. The recovery of a gasoline spiked with approximately 4 microg/g elemental sulfur was 102%. The presence of ethanol did not appear to affect results.