Liquid Chromatography and Lipid Analysis

When considering necessary food testing protocols to ensure both food safety and nutritional composition, one area of interest is lipid analysis. Lipids (including fatty acids, triglycerides, waxes, steroids, and phospholipids) play important biological functions and are used in cooking and food production. In terms of analysis, primary reasons for lipid characterization and quantification include maintaining accurate labeling, ensuring food quality, recognizing and preventing lipid oxidation, detecting adulteration and optimizing processing. The actual process of lipid analysis can be complicated by virtue of the characteristics of the lipids themselves. Gas chromatography may be used, but many lipids must be derivatized prior to separation and detection. This renders the method labor intensive and inefficient. High performance liquid chromatography (HPLC) may be preferable, although this approach is not without its own challenges. The most notable issue is that, because lipids lack chromophores, UV absorbance cannot be used for detection. A common alternative detector, evaporative light scattering, is also less than ideal, particularly in the analysis of triglycerides, since the results demonstrate it has a limited dynamic range and is less sensitive. For this reason, researchers recently used an Accucore C18 column (Thermo Scientific) and a Corona ultra RS charged aerosol detector (CAD) (Thermo Scientific) for HPLC separation and detection of lipids. This system nebulizes the analyte prior to charging it for measurement with an electrometer. The HPLC/CAD approach is effective with various lipids, including complex oils, requires minimal dilution and can be combined with mass spectrometry so that a single HPLC run yields complete lipid composition analysis. The researchers were able to use two complex oils, algal and emu respectively, to demonstrate the method’s resolution and quantitative parameters. They found that the sensitivity of the method is linked to each analyte’s natural boiling point with 300 degrees celsius emerging as the outside limit for detectability. In terms of detection capabilities, most analytes fell in the 2 to 20 ng on column range. Dionex Chromeleon software (Thermo Scientific) efficiently processes data, including non-linear calibration curves and powerful quantification. Overall, HPLC with Corona charged aerosol detection is an efficient, sensitive option for general lipid analysis for a broad range of lipid classes. The general nature of this approach may render it a versatile tool for a variety of testing applications. To read the full application note, please follow the link: https://static.thermoscientific.com/images/D22386~.pdf Interested in what you’ve read here? Let us know, and share with a colleague.