A simple and reproducible quantitative method of acid catalysed transesterification of lipids is described, utilisable for sample quantities from several hundreds of pg to several hundreds of mg. It consists in heating the sample with a transesterification mixture (chloroform, methanol and acetylchloride) in a sealed glass ampoule or in a vial and subsequent neutralization of the hydrogen chloride formed with silver carbonate. After centrifugation the supernatant can be analyzed directly by GC, GC-MS, or also furhter separated by means of TLC, C C or HPLC. Quantitative studies can be carried out especially with lipids containing short chain fatty acids in their molecule, beginning with 2-methyl propanoic acid (i-4:O). Description of all significant gas chromatography peaks of individual components of the transesterification mixture is presented, before and after the reaction, in relation to the peaks of methyl esters of short chain fatty acids.
Einfache quantitative Umesterung von Lipiden -2. Anwendungen. Folgende Proben biologischen Ursprungs wurden mit methanolischer Chlorwasserstofflosung, hergestellt durch Umsetzung von Acetylchlorid mit Methanol, umgeestert: Triglyceride aus dem Samenol von schwarzen Johannisbeeren, aus Butter, Schweinefettgewebe, Fettgewebe aus inneren Teilen der Gans, lyophilisiertem Plasma von Menschenblut, Larven der Fleischfliege der Gattung Sarcophaga, Lipid A aus Shigella dysenteriae, Ester aus Bienenwachs und Ester aus cuticularen Lipiden der Griinen Erbsenblattlaus Acyrthosiphon pisum. Sterinester und freie Fettsauren wurden ebenfalls analysiert. Die Bedingungen der Umesterung sowie die Bedingungen der gaschromatographischen Analyse der Komponenten nach Umesterung werden diskutiert.
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