Rapid characterization of lipids by MALDI MS. Part 1: Bacterial taxonomy and analysis of food oils

by Lay, Jackson O., Jr.; Gidden, Jennifer; Liyanage, Rohana; Emerson, Beth; Durham, Bill

A review. Several new methods have been developed recently that allow the direct detection of lipids without resorting to derivatization or chromatog. sepn. The simplest of these is direct MALDI (matrix-assisted laser desorption/ionization) mass spectrometry. This approach is most useful for mixts. that contain minimal amts. of ion-suppressing interfering components. However, even when such components are present, their effects can often be minimized by using simple sepn. techniques beforehand, such as solid phase extn. or thin layer chromatog. For example, direct MALDI has been used for rapid screening of lipids and for taxonomic identification of the source organisms with no sample pretreatment. Fractions collected from solid phase extn. cartridges have also been used to avoid the most extreme effects of ion suppression from more complex lipid mixts. More recently, direct MALDI has been applied to the anal. of TLC plates allowing the detection of TLC-sepd. lipids from the complex lipidome. Herein, we briefly describe the application of rapid MALDI MS to some typical research problems involving the characterization of lipids. In Part 1 these include bacterial taxonomy by direct anal. of intact lipids in simple exts. rather than by conversion to fatty acid Me esters. Food oils such as triacylglycerols can be characterized simply and easily by direct MALDI MS without resort to any sort of sepn. Part 2 (in the next issue of Lipid Technol.) will cover the spontaneous fragmentation of protonated lipids, ion suppression and the use of solid phase extn. and thin layer chromatog. with MALDI MS to characterize complex biol. samples.

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