Table 1.
Values of m/z with high resolution mass accuracy, predicted molecular formula, ion description, error in ppm (Delta ppm) and tentative attribution of lipids detected in negative and positive ion modes by DESI-MS.
| Ions | Predicted Molecular formula | Ion description | Delta ppma | Attributionb |
|---|---|---|---|---|
| 253.21610 | C16H29O2 | [M-H]− | −1.203 | 16:1c (palmitoleic acid) |
| 255.23173 | C16H31O2 | −1.224 | 16:0 (palmitic acid) | |
| 279.23163 | C18H31O2 | −1.324 | 18:2 (linoleic acid) | |
| 281.24728 | C18H33O2 | −1.324 | 18:1 (oleic acid) | |
| 283.26290 | C18H35O2 | −1.354 | 18:0 (stearic acid) | |
| 303.23150 | C20H31O2 | −1.454 | 20:4 (arachidonic acid) | |
| 311.29407 | C20H39O2 | −1.484 | 20:0 (eicosanoic acid) | |
| 329.24708 | C22H33O2 | −1.524 | 22:5 (docosapentaenoic acid) | |
| 339.32558 | C22H43O2 | −1.274 | 22:0 (docosanoic acid) | |
| 465.30219 | C27H45O4S | −2.214 | Cholesterol sulphate | |
| 511.47073 | C32H63O4 | −2.454 | FA dimer | |
| 537.48644 | C34H65O4 | −2.394 | FA dimer | |
| 539.50207 | C34H67O4 | −2.414 | FA dimer | |
| 559.47058 | C36H63O4 | −2.604 | FA dimer | |
| 585.50738 | C35H69O6 | −2.583 | FA dimer | |
| 609.48489 | C40H65O4 | −3.944 | FA dimer | |
| 788.54144 | C42H79O10NP | −3.267 | PS (36:1) | |
| 747.51486 | C40H76O10P | −2.201 | PG (34:1) | |
| 804.57281 | C43H83O10NP | −3.197 | PS (37:0) | |
| 835.53082 | C43H80O13P | −3.382 | PI (34:1) | |
| 857.51494 | C45H78O13P | −3.612 | PI (36:4) | |
| 885.54613 | C47H82O13P | −3.722 | PI (38:4) | |
| 887.56518 | C47H84O13P | −0.322 | PI (38:3) | |
| 686.18886 | C30H50O3NAg2 | [M+Ag2NO3]+ | 0.223 (for m/z | Squalene |
| 686.18803)d | ||||
| 725.42684 | C39H70O5Ag | [M+Ag]+ | −0.041 | DAG (36:2)c |
| 751.44284 | C41H72O5Ag | 0.426 | DAG (38:4) | |
| 909.60999 | C51H94O6Ag | 0.0445 | TAG (48:2) | |
| 911.62492 | C51H96O6Ag | −0.346 | TAG (48:1) | |
| 935.62574 | C53H96O6Ag | 0.540 | TAG (50:3) | |
| 937.64121 | C53H98O6Ag | 0.346 | TAG (50:2) | |
| 939.65570 | C53H100O6Ag | −0.889 | TAG (50:1) | |
| 961.64088 | C55H98O6Ag | −0.005 | TAG (52:4) | |
| 963.65635 | C55H100O6Ag | −0.192 | TAG (52:3) | |
| 965.65848 | C55H102O6Ag | 1.606 | TAG (52:2) | |
| 987.65692 | C57H100O6Ag | 0.390 | TAG (54:5) | |
| 989.67258 | C57H102O6Ag | 0.399 | TAG (54:4) | |
| 991.69092 | C57H104O6Ag | 3.111 | TAG (54:3) | |
| 1013.67296 | C59H102O6Ag | 0.764 | TAG (56:4) | |
| 1015.68910 | C59H104O6Ag | 1.245 | TAG (56:3) | |
| 1037.67308 | C61H102O6Ag | 0.862 | TAG (58:8) | |
| 1039.68994 | C61H104O6Ag | 2.024 | TAG (58:7) | |
| 1041.70459 | C61H106O6Ag | 1.060 | TAG (58:6) | |
| 1140.48205 | C59H90O7NAg2 | [M+Ag2NO3]+ | −0.612 (for m/z 1138.48184)d | Ubiquinone (Coenzyme Q10) |
Delta ppm column displays the difference between the specified mass and the calculated mass in ppm units.
Attribution of lipids is based on Lipid Maps (www.lipidmaps.org) and Metlin (http://metlin.scripps.edu) searches of the predicted molecular formulae and possible adducts.
(C:U) represents the number of carbon atoms (C) and the number of unsaturations (U) of the fatty acyl chains.
Abbreviations used: DAG – diacylglycerol; FA, fatty acid; PI- phosphatidylinositol; PS - phosphatidylserine; PG - Phosphatidylglycerol, TAG – triacylglycerol. The ‘o-’ suffix is used to indicate the presence of an alkyl ether substituent, whereas the ‘p-’ suffix is used for the 1Z-alkenyl ether (plasmalogen) substituent.
Due to the fact the squalene and ubiquinone were adducts presenting Ag2NO3, the exact mass has been calculated based on the monoisotopic mass as reported in PLoS One. 2013 Sep 20;8(9):e74981.