Table 1.
Characteristics of the putatively identified marker metabolites in liquid chromatography-mass spectrometry analysis
| Column | Ionization mode | MW | m/z | RT (min) | Putative annotation | CID (eV) | MS/MS fragmentation | Identification referencea |
|---|---|---|---|---|---|---|---|---|
| HILIC | ESI+ | 231.148 | 232.155 | 1.59 | Unknown metabolite, putative carnitine | 10 | 232.1531, 85.0290, 173.0782, 95.0856, 60.0803 | MS/MS |
| HILIC | ESI+ | 136.064 | 137.071 | 2.22 | 1-methylnicotinamide | 20 | 94.0654, 137.0688, 65.0379, 77.0375 | MID274 |
| RP | ESI+ | 189.043 | 190.050 | 3.23 | Kynurenic acid (KYNA) | 10 | 190.0496, 144.0443, 172.0426 | MID5683 |
| HILIC | ESI− | 165.079 | 164.071 | 3.91 | Phenylalanine | 10 | 164.0713, 103.0565, 147.0448, 90.0116, 72.0086 | MID28 |
| RP | ESI+ | 175.064 | 176.071 | 5.01 | Indoleacetic acid | 10 | 130.0656, 176.0780, 51.0227, 158.0587 | HMDB 00197 |
| RP | ESI+ | 189.079 | 190.086 | 5.77 | 3-Indolepropionic acid (IPA) | 10 | 130.0655, 55.0184, 172.0754, 190.0862 | MID6602 |
| HILIC | ESI+ | 220.143 | 221.150 | 7.30 | Unknown metabolite | 10 | 221.1465, 84.0806, 87.0429, 90.9738, 203.1374 | MS/MS |
| RP | ESI+ | 467.303 | 468.310 | 9.76 | sn-1 LysoPC(14:0) | 40 | 184.0741, 86.0970, 125.0017, 60.0814, 104.1076; ESI(−) 10 eV: 227.1995, 452.2768, 512.3016 | MS/MS |
| RP | ESI− | 563.323 | 562.316 | 9.85 | sn-1 LysoPC(18:3) | 10 | 502.2892, 277.2167, 562.3029; ESI(+) 20 eV: 184.0740, 104.1083 | MS/MS |
| RP | ESI+ | 499.271 | 500.278 | 9.87 | sn-1 LysoPE(20:5) | 10 | 500.2786, 359.2548; ESI(−) 20 eV: 498.2860, 169.1368, 301.2172 | MS/MS |
| RP | ESI+ | 481.319 | 482.326 | 10.03 | sn-1 LysoPC(15:0) | 20 | 184.0751, 104.1059, 482.3264; ESI(−) 10 eV: 241.2097, 466.2915 | MS/MS |
| RP | ESI− | 477.287 | 476.280 | 10.12 | sn-1 LysoPE(18:2) | 20 | 279.2321, 196.0390, 140.0058, 78.9594, 476.2834; ESI(+) 10 eV: 478.2932, 337.2703 | MS/MS |
| RP | ESI− | 479.302 | 478.295 | 10.29 | sn-1 LysoPE(18:1) | 10 | 281.2477, 478.2945, 196.0306; ESI(+) 10 eV: 480.3077, 44.0505, 62.0614, 339.2930, 462.3008 | MS/MS |
| RP | ESI+ | 545.350 | 546.357 | 10.29 | sn-1 LysoPC(20:3) | 10 | 546.3626, 104.1084, 184.0740; ESI(−) 10 eV: 530.3529, 305.2466, 590.3485 | MS/MS |
| RP | ESI+ | 509.350 | 510.357 | 10.42 | sn-1 LysoPC(17:0) | 20 | 184.0740, 104.1066, 510.3602; ESI(−) 10 eV: 494.3250, 269.2425, 554.3709 | MS/MS |
| RP | ESI− | 481.319 | 480.313 | 10.65 | sn-1 LysoPE(18:0) | 10 | 283.2631, 480.3112, 196.0353; ESI(+) 10 eV: 341.3049, 482.3239, 44.0494, 464.3121 | MS/MS |
| RP | ESI− | 304.241 | 303.235 | 10.70 | Arachidonic acid (C20:4) | 10 | 303.2354, 59.0219, 259.2326 | LipidMaps |
| RP | ESI− | 643.406 | 642.398 | 10.72 | Unknown metabolite, putative GlcCer(d18:1/12:0) or GlcCer(d14:1/16:0) | 20 | 642.3955, 362.1501, 363.1579, 99.9224 | Hsu and Turk [25] |
| RP | ESI+ | 282.257 | 283.264 | 10.94 | C18:1 | 10 | 283.2847, 43.0540, 71.0867, 149.1310, 57.0704, 101.0773 | LipidMaps |
| RP | ESI− | 647.438 | 646.431 | 10.94 | Unknown metabolite, putative Cer(d18:1/24:1) | 40 | 99.9224, 364.1699, 281.2448, 365.1777, 83.9307, 320.1746, 646.4291 | Hsu and Turk [25] |
| RP | ESI+ | 584.263 | 585.270 | 11.35 | Bilirubin | 10 | 299.1388, 585.2677 | MID81 |
| RP | ESI− | 847.538 | 846.532 | 11.56 | PC(20:5/18:3) | 40 | 303.2314, 102.9687, 301.2127; ESI(+) 20 eV: 184.0735, 802.5399 | MS/MS |
| RP | ESI− | 797.523 | 796.516 | 11.59 | Unknown PC | 10 | 736.4868, 796.5069; ESI(+) 20 eV: 184.0733, 752.5218 | MS/MS |
| RP | ESI− | 799.538 | 798.531 | 11.81 | PC(20:4/14:0) | 20 | 738.5067, 303.2318, 227.1970, 798.5315; ESI(+) 10 eV: 754.5405, 184.0726 | MS/MS |
| RP | ESI− | 825.555 | 824.547 | 11.83 | PC(18:3/18:2) | 20 | 764.5239, 824.5378, 277.2097, 279.2388, 45.0065; ESI(+) 20 eV: 184.0740, 780.5574, 86.0961 | MS/MS |
| RP | ESI− | 801.553 | 800.547 | 12.04 | PC(18:2/16:1) | 20 | 740.5268, 279.2323, 253.2152, 800.5403; ESI(+) 10 eV: 756.5574, 184.0733 | MS/MS |
| RP | ESI+ | 743.549 | 744.556 | 12.08 | PC(15:0/18:2) | 10 | 744.5577, 184.0743; ESI(−) 20 eV: 728.5133, 788.5291, 241.2161, 279.2331 | MS/MS |
Metabolites with uncertain identity are also included. The characteristics include the identification references together with parameters for the LC–MS analysis, including the chromatography (column), ionization mode in the mass spectrometry (Ionization mode), MW molecular weight, identified ion (m/z), RT retention time, CID collision-induced dissociation energy, MS/MS fragments fragment ions in the tandem mass spectrometry
LysoPC lysophosphatidylcholine, LysoPE lysophosphatidylethanolamine, PC phosphatidylcholine
aIdentification of metabolites is based on manual MS/MS spectral interpretation, METLIN ID when MS/MS spectrum available, commercial standard compound or some fragmentation patterns published earlier [25]