Evaluation of the retention pattern on ionic liquid columns for gas chromatographic analyses of fatty acid methyl esters

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.

The Influence of Ionic Liquids on the Effectiveness of Analytical Methods Used in the Monitoring of Human and Veterinary Pharmaceuticals in Biological and Environmental Samples-Trends and Perspectives

Recent years have seen the increased utilization of ionic liquids (ILs) in the development and optimization of analytical methods. Their unique and eco-friendly properties and the ability to modify their structure allows them to be useful both at the sample preparation stage and at the separation stage of the analytes. The use of ILs for the analysis of pharmaceuticals seems particularly interesting because of their systematic delivery to the environment. Nowadays, they are commonly detected in many countries at very low concentration levels. However, due to their specific physiological activity, pharmaceuticals are responsible for bioaccumulation and toxic effects in aquatic and terrestrial ecosystems as well as possibly upsetting the body's equilibrium, leading to the dangerous phenomenon of drug resistance. This review will provide a comprehensive summary of the use of ILs in various sample preparation procedures and separation methods for the determination of pharmaceuticals in environmental and biological matrices based on liquid-based chromatography (LC, SFC, TLC), gas chromatography (GC) and electromigration techniques (e.g., capillary electrophoresis (CE)). Moreover, the advantages and disadvantages of ILs, which can appear during extraction and separation, will be presented and attention will be given to the criteria to be followed during the selection of ILs for specific applications.

Chromatographic efficiency of polar capillary columns applied for the analysis of fatty acid methyl esters by gas chromatography

The chromatographic efficiency that could be achieved in temperature-programmed gas chromatography was compared for four capillary columns that are typically applied for analysis of fatty acid methyl esters (FAME). Three different carrier gases, hydrogen, helium and nitrogen, were applied. For each experiment, the carrier gas velocities and the temperature rates were varied with a full 9 × 3 design, with nine levels on the carrier gas velocity and temperature rates of 1, 2 or 3°C/min. Response surface methodology was used to create models of chromatographic efficiency as a function of temperature rate and carrier gas velocity. The chromatographic efficiency was defined as the inverse of peak widths measured in retention index units. The final results were standardized so that the efficiencies that could be achieved within a certain time frame, defined by the retention time of the last compound in the chromatogram, could be compared. The results show that there were clear differences in the efficiencies that could be achieved with the different columns and that the efficiency decreased with increasing polarity of the stationary phase. The differences can be explained by higher resistance to mass transfer in the stationary phase in the most polar columns.

Ionic liquids as stationary phases for fatty acid analysis by gas chromatography

The present paper provides an overview of the application of ionic liquid (IL) columns for GC analysis of fatty acid methyl esters (FAMEs).