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The Bottom Up Solution to the Triacylglycerol Lipidome

W.C. Byrdwell, Florida Atlantic University, USA.

 

Work over the last several years has shown the utility of using the fragments in atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) mass spectra for the regiospecific analysis of triacylglycerols (TAG).  Specifically, for an ABA/AAB TAG, the [AA]+/[AB]+ ratio has been used to produce a quantitative estimation of the relative amounts of specific regioisomers.  Also, it has been shown that the abundance of the protonated molecule and the diacylglycerol fragment ions, [DAG]+, formed by APCI-MS depends on the amount of unsaturation in a TAG molecule.  Therefore, the ratio of the protonated molecule, [M+H]+, to the sum of the [DAG]+ may be correlated to the degree of unsaturation in a TAG molecule.  Presented here is an approach to determining the identities of triacylglycerols (TAG) by constructing ‘Critical Ratios’ from the abundances of the protonated molecule, [M+H]+, and the diacylglycerol fragment ions obtained by HPLC/APCI-MS.  These Critical Ratios provide direct information regarding the structural characteristics of the TAG.  For instance, one of the two Critical Ratios constructed for an ABA/AAB TAG can be used to determine the relative amounts of the regioisomers of a TAG.  An ‘AAA’-type TAG has only one Critical Ratio, an ‘ABA/AAB’-type TAG has two Critical Ratios, and an ‘ABC’-type TAG has three Critical Ratios.  It is shown that, in addition to providing direct structural information, the Critical Ratios actually constitute a ‘reduced data set’ from which the mass spectrum of any individual TAG can be reconstructed in its entirety.  To do this, the Critical Ratios are processed through a construct that contains a series of conditional tests leading to final equations.  The construct contains a series of Critical Values and Critical Limits that allow the TAG to be categorized into Cases.  The Cases define the exact form of the equations to be used to calculate the specific abundances of the protonated molecule, [M+H]+, and all [DAG]+ fragment ions.  Since the mass spectrum of any TAG can be reproduced using this construct, it is referred to as a solution to the TAG lipidome (the set of all possible structures of TAG).  This complete construct is referred to as ‘The Bottom-Up Solution to the Triacylglycerol Lipidome’.

The Powerpoint presentation given by the link below was presented at the 96th Annual Meeting of the American Oil Chemists’ Society in Salt Lake City, Utah on Monday afternoon, May 2, 2005. The abstract of this presentation is given below. Follow the link below the abstract to view the presentation.

The Powerpoint presentation may be accessed by clicking

HERE

The file size is ~ 1.5 Mb

Please note that the powerpoint presentation contains automatically timed events and text. When run as a slide show, the text and graphics appear and disappear in synchronization, so they do not overlap. When looking at the raw file, text and figures may appear overlapped. When the slide show is run, the text does not overlap in time.

© 2005-2009

The names “The Bottom Up Solution” and “The Unit Simulacrum” and all equations, figures and schemes are copyrighted in 2005-2009 by William Craig Byrdwell.  No portion of the equations, figures or schemes may be used without prior written permission from the copyright holder, William Craig Byrdwell.