Table 1.

Summary of the Major Molecular Lipid Components in Human Meibum^*

Species	Composition
Wax esters	CnH2nO2 (n = 39–41, 43), n: 0
	CnH2n−2O2 (n = 38–47), n: 1
	CnH2n−4O2 (n = 34, 38–50), n: 2
	CnH2n−6O2 (n = 40–50), n: 3
	CnH2n−8O2 (n = 44), n: 4
	CnH2n−10O2 (n = 44), n: 5
Cholesteryl esters	Cn−1H2n−1COOC27H45 (n = 20–29), n: 0
	Cn−1H2n−3COOC27H45 (n = 20–26, 28, 30, 32), n: 1
	Cn−1H2n−5COOC27H45 (n = 20, 22, 24), n: 2
Diesters
α, ω Type II	CnH2n−6O4 (n = 64–67), n: 2
	CnH2n−8O4 (n = 64, 66–68, 70), n: 3
	CnH2n−10O4 (n = 66, 68, 70), n: 4
ω Type I-St	(CnH2n−5O3)OC27H45 (n = 46–51), n: 1
	(CnH2n−7O3)OC27H45 (n = 44, 46, 48–52), n: 2
	(CnH2n−9O3)OC27H45 (n = 48, 50, 52), n: 3
Triacyglycerols	CnH2n−8O6 (n = 55, 57), n: 2
	CnH2n−10O6 (n = 55, 57), n: 3
Free fatty acids	CnH2nO2 (n = 12, 14–18, 20–29), n: 0
	CnH2n−2O2 (n = 16–18, 20, 22, 24, 26, 28, 30, 32), n: 1
	CnH2n−4O2 (n = 18), n: 2
(O-acyl)-ω-hydroxy fatty acids	CnH2n−4O4 (n = 42–50), n: 1
	CnH2n−6O4 (n = 42, 44, 46, 48–52), n: 2
	CnH2n−8O4 (n = 48, 50, 52), n: 3
	CnH2n−10O4 (n = 50, 52), n: 4

^*The assignments were considered only when the corresponding mass accuracies were within ± 5 ppm for positive mode and within ± 12 ppm for negative mode (free fatty acids and (O-acyl)-ω-hydroxy fatty acids).