Lipid Class Specific Fragments

Positive ion mode

Lipid classes	Prec. ion	FragmentNeutral loss	AnnotationLevel	Example (QQQ)	Remark
PC	[M+H]+	m/z 184.0733NL 183.0661	Sum composition	Precursor m/z 746.6PC O-34:1*PC 33:1**	1
PE	[M+H]+	NL 141.0191	Sum composition	Precursor m/z 704.5PE O-34:1*PE 33:1**	1
MMPE	[M+H]+	NL 155.0347	Sum composition	Precursor m/z 718.5MMPE O-34:1*MMPE 33:1**	1
DMPE	[M+H]+	NL 169.0503m/z 170.0576	Sum composition	Precursor m/z 732.6DMPE O-34:1*DMPE 33:1**	1
PS	[M+H]+	NL 185.0089	Sum composition	Precursor m/z 748.5PS O-34:1*PS 33:1**	1
PG	[M+NH4]+	NL 189.0402	Sum composition	Precursor m/z 752.5PG O-34:1*PG 33:1**	1
PA	[M+NH4]+	NL 115.0035NL 17.0266	Sum composition	Precursor m/z 678.5PA O-34:1*PA 33:1**	1; NL of 17 has a low specificity
PI	[M+NH4]+	NL 277.0563	Sum composition	Precursor m/z 840.6PI O-34:1*PI 33:1**	1
LPX	see respective diradyl lipid class	Molecular lipid species	Precursor m/z 482.3LPC O-16:0*LPC 15:0**	1
DG	[M+NH4]+	NL 35.0371NL 17.0266	Sum composition	Precursor m/z 598.5DG O-34:1*DG 33:1**	1; NL of 17 has a low specificity
SM	[M+H]+	m/z 184.0733	Sum composition	Precursor m/z 703.6SM 34:1*SM 33:2**	2
CerHexCerHex2Cer	[M+H]+	Long chain base specific product ions: e.g. m/z 264.2685 for SPH d18:1 backbone	Molecular lipid species	Cer d18:1/16:0

Remarks:

1. Isobaric overlap of species may require assumptions:
   • *only acyl chains with even number of C-atoms
   • **only ester bonds are present
2. Isobaric overlap of species may require assumptions:
   • *sphingoid base with two hydroxyl-groups
   • **sphingoid base with three hydroxyl-groups

Negative ion mode

Lipid classes	Prec. ion	Fragment Neutral loss	AnnotationLevel	Example	Remark
PC	[M+HCOO]–	NL 60.0211	Sum composition	Precursor m/z 790.6PC O-34:1*PC 33:1**	1
PC	[M+CH3COO]–	NL 74.0368	Sum composition	Precursor m/z 804.6PC O-34:1*PC 33:1**	1
PE	[M-H]–	m/z 140.0118m/z 196.0380	Sum composition	Precursor m/z 702.5PE O-34:1*PE 33:1**	1
PG	[M-H]–	m/z 152.9958m/z 171.0063	Sum composition	Precursor m/z 733.5PG O-34:1*PG 33:1**	1
PA	[M-H]–	m/z 152.9958	Sum composition	Precursor m/z 659.5PA O-34:1*PA 33:1**	1
PI	[M-H]–	m/z 241.0119m/z 223.0013m/z 152.9958m/z 259.0224	Sum composition	Precursor m/z 821.5PI O-34:1*PI 33:1**	1
PS	[M-H]–	m/z 152.9958NL 87.0320	Sum composition	Precursor m/z 746.5PS O-34:1*PS 33:1**	1
DMPE	[M-H]-	m/z 168.0431	Sum composition	Precursor m/z 730.6DMPE O-34:1*DMPE 33:1**	1
SM	[M+HCOO]-	m/z 168.0431NL 60.0211	Sum composition	Precursor m/z 747.6SM 34:1*SM 33:2**	2
SM	[M+CH3COO]-	m/z 168.0431NL 74.0368	Sum composition	Precursor m/z 761.6SM 34:1*SM 33:2**	2
LPXs	see respective non-lyso lipid class	Molecular lipid species	Precursor m/z 438.3LPE O-16:0*LPE 15:0**	1

Remarks:

1. Isobaric overlap of species may require assumptions:
   • *only acyl chains with even number of C-atoms
   • **only ester bonds are present
2. Isobaric overlap of species may require assumptions:
   • *sphingoid base with two hydroxyl-groups
   • **sphingoid base with three hydroxyl-groups