Meibum is believed to be the major source of tear !lm lipids, which are vital in the prevention of excess
evaporation of the aqueous phase. The complete lipid composition of meibum has yet to be established.
While earlier studies reported the presence of phospholipids in human meibum, recent mass spectrometric
studies have not detected them. In this study we use electrospray ionisation tandem mass
spectrometry to investigate the presence of phospholipids in meibum and provide comparison to the
phospholipid pro!le of tears.
Lipids were extracted from human meibum and tear samples using standard biphasic methods and
analysed by nano-electrospray ionisation tandem mass spectrometry using targeted ion scans. A total of
35 choline-containing phospholipids were identi!ed in meibum and the pro!le of these was similar to
that observed in tears, suggesting tear lipids are derived from meibum. The results shown here highlight
the need for a combination of optimised techniques to enable the identi!cation of the large range of lipid
classes in meibum.