Positive ion mode

Lipid classes

Prec. ion

Fragment

Neutral loss

Annot.

Level

Example

Remark

Glycerophospholipids

[M+H]+

NL -FA X1:Y1(+HO)

NL -FA X2:Y2(+HO)

NL -FA X1:Y1(-H)

NL -FA X2:Y2(-H)

Molecular lipid species

PC 16:0_18:1

NL of fatty acid and ketene

LPX

see respective diradyl lipid class

Molecular lipid species

Precursor m/z 482.3

LPC O-16:0*

LPC 15:0**

 1

Cer

HexCer

Hex2Cer

 [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

Negative ion mode

Lipid classes

Prec. ion

Fragment

Neutral loss

Annot.

Level

Example

Remark

Glycerophospholipids
(except PC)

[M-H]-

 

FA X1:Y1(+O)

FA X2:Y2(+O)

additional:
NL -FA X1:Y1(+HO)

NL -FA X2:Y2(+HO)

NL -FA X1:Y1(-H)

NL -FA X2:Y2(-H)

Molecular lipid species

PX 16:0_18:1

both acyl chain fragments should be observed;

additional evidence from NL of fatty acid and ketene

PC

[M-CH3COO]-

[M-HCOO]-

FA X1:Y1(+O)

FA X2:Y2(+O)

additional:

NL -FA X1:Y1(+HO)

NL -FA X2:Y2(+HO)

NL -FA X1:Y1(-H)

NL -FA X2:Y2(-H)

Molecular lipid species

PC 16:0_18:1

both acyl chain fragments should be observed;

additional evidence from NL of fatty acid and ketene

LPX

see respective non-lyso lipid class

Molecular lipid species

Precursor m/z 438.3

LPE O-16:0*

LPE 15:0**

 Remarks:

  1. Isobaric overlap of species may require assumptions:
    • *only acyl chains with even number of C-atoms
    • **only ester bonds are present