The growth of lipidomics can be traced to the developments in mass spectrometry, most notably electrospray ionization (ESI), which have enabled the analysis of complex non-volatile lipids by mass spectrometry (MS).  From a lipidomic perspective, the analysis of CD1 bound lipid antigens presents specific analytical challenges.  The potential for CD1 to present both mammalian self and foreign lipids from a variety of sources (microbial, botanical, synthetic etc.) results in an enormous breadth in potential antigenic lipids, making their identification and characterization a significant challenge. The considerable chemical diversity that arises as a result necessitates adopting a liquid chromatography mass spectrometry (LC-MS) approach applicable to a broad range of lipids.  Furthermore, the quantity of sample available for mass spectrometric analysis is often limited and consequently there is a strong motivation to develop mass spectrometry approaches with greater sensitivity.

The use of nano-electrospray ionization (nESI) is known to increase ionization efficiency, and consequently sensitivity, in comparison with traditional ESI sources.  Similarly, nano-LC has the potential to reduce sample requirements over more traditional modes of analytical LC.  While nESI has found extensive application in shotgun lipidomics, involving the direct analysis of lipid extracts without chromatographic separation, there has been limited work using nano-LC coupled to nESI sources for lipid analysis.  This is in spite of the widespread application of this approach in related fields such as proteomics. 

Here we present the development of methodology using nano-LC-nESI-MS for the analysis of lipids and discuss the potential advantages of this approach in the context of lipid antigen identification.