Table 2.
Summary of class-related regiochemical assignment by ESI-MS/MS of phospholipids, sulfolipids, and glycolipids along with their lyso forms identified in the lipid extract of wakame brown alga (U. pinnatifida).
| Lipid Class | Precursor Ion | Diagnostic Product Ion for Regiochemical Assignment: sn-1/sn-2 | Comparison between Peak Signal Intensity | Ref. |
|---|---|---|---|---|
| SQDG | [M-H]− | [M-H-R1COOH]−; [M-H-R2COOH]− | [M-H-R1COOH]− > [M-H-R2COOH]− | [31] |
| SQMG | [M-H]− | m/z 243.0, [C6H11O8S]− | Product ion is generated if the FA is at sn-2 | [32] |
| DGDG | [M+Na]+ | [M+Na-R1COOH]+; [M+Na-R2COOH]+ | [M+Na-R1COOH]+ > [M+Na-R2COOH]+ | [37] |
| PG | [M-H]− | [M-H-R1COOH]−; [M-H-R2COOH]− | [M-H-R2COOH]− > [M-H-R1COOH]− | [38] |
| PI | [M-H]− | [M-H-R1COOH]−; [M-H-R2COOH]− | [M-H-R2COOH]− > [M-H-R1COOH]− | [39] |
| PA | [M-H]− | [M-H-R1COOH]−; [M-H-R2COOH]− | [M-H-R2COOH]− > [M-H-R1COOH]− | [40] |
| PE | [M-H]− | [M-H-R’1=C=O]−; [M-H-R’2=C=O]− | [M-H-R’2=C=O]− > [M-H-R’1=C=O]− | [41] |
| LPE | [M-H]− | m/z 196.1, [M-H-RCOOH]−; | If RCOOH is in sn-1: [M-H-RCOOH]− > [M-H-R’=C=O]− else viceversa |
[42] |
| m/z 214.1, [M-H-R’=C=O]− | ||||
| PC | [M-CH3]−, | [M-CH3-R’1=C=O]−; [M-CH3-R’2=C=O]− | [M-CH3-R’2=C=O]− > [M-CH3-R’1=C=O]− | [43] |
| [M+HCOO]− | ||||
| LPC | [M-CH3]−, | m/z 224.1, [M-CH3-RCOOH]− | If RCOOH is in sn-1: [M-CH3-RCOOH]− > [M-CH3-R’=C=O]− else viceversa |
[42] |
| [M+HCOO]− | m/z 242.1, [M-CH3-R’=C=O]− |