General strategies in chromatographic analysis of lipids

Lipid extracts of natural sources contain a large number of lipid classes and molecular species. Completely reproducible samples are obtained only with great care and skill. Analytical methods other than chromatography and/or mass spectrometry are of little use for resolution and identification of lipid molecules even in simple mixtures. The analytical information desired governs the selection of the chromatographic and mass spectrometric method, which determine the sample preparation and derivative needed. Usually a combination of chromatographic methods is necessary to identify specific species of lipids. The recent development of soft ionization techniques, that are readily interfaced with mass spectrometers, have greatly simplified the sample preparation and have largely eliminated the need for derivatization. Because these techniques require expensive equipment and dedicated operators, the methods selected must be consistent with the true analytical needs and the available resources. Although personal preference cannot be eliminated entirely, the general strategies outlined below should help to reduce the number of possibilities facing a lipid analyst to a few practical choices.