Journal of Lipid Research
Volume 60, Issue 11, November 2019, Pages 1968-1978
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Methods
Analytical separations for lipids in complex, nonpolar lipidomes using differential mobility spectrometry

https://doi.org/10.1194/jlr.D094854Get rights and content
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Secretions from meibomian glands located within the eyelid (commonly known as meibum) are rich in nonpolar lipid classes incorporating very-long (22–30 carbons) and ultra-long (>30 carbons) acyl chains. The complex nature of the meibum lipidome and its preponderance of neutral, nonpolar lipid classes presents an analytical challenge, with typically poor chromatographic resolution, even between different lipid classes. To address this challenge, we have deployed differential mobility spectrometry (DMS)-MS to interrogate the human meibum lipidome and demonstrate near-baseline resolution of the two major nonpolar classes contained therein, namely wax esters and cholesteryl esters. Within these two lipid classes, we describe ion mobility behavior that is associated with the length of their acyl chains and location of unsaturation. This capability was exploited to profile the molecular speciation within each class and thus extend meibum lipidome coverage. Intriguingly, structure-mobility relationships in these nonpolar lipids show similar trends and inflections to those previously reported for other physicochemical properties of lipids (e.g., melting point and phase-transition temperatures). Taken together, these data demonstrate that differential ion mobility provides a powerful orthoganol separation technology for the analysis of neutral lipids in complex matrices, such as meibum, and may further provide a means to predict physicochemical properties of lipids that could assist in inferring their biological function(s).

wax esters
cholesteryl esters
meibum
lipidomics
mass spectrometry
ion mobility

Cited by (0)

This work was supported by Australian Research Council Linkage Project GrantLP140100711 (with industry support from Allergan), Discovery Project Grants DP150101715 and DP190101486 and Future Fellowship Grant FT110100249 (T.W.M.).

The online version of this article (available at http://www.jlr.org) contains a supplement.

    Abbreviations:

    CCS

    collisional cross-section

    CE

    cholesteryl ester

    CV

    compensation voltage

    DMS

    differential mobility spectrometry

    DTIMS

    drift-time ion mobility spectrometry

    IMS

    ion mobility spectrometry

    MRM

    multiple reaction monitoring

    OzID

    ozone-induced dissociation

    SV

    separation voltage

    TG

    triacylglycerol

    TWIMS

    traveling-wave ion mobility spectrometry

    WE

    wax ester

1

Present address of S. E. Hancock: School of Medical Sciences, University of New South Wales, Sydney, Australia.