Table 2.
Abundance of N-glycans in human serum. Relative molar abundances were calculated from the peak areas of the monoisotopic peaks and normalized to the earliest eluted G2S2 (Na6-4Na6-4) variant by the respective correction factors given in Fig. 1
| Isomer | Uncorrected relative abundance (%) | Instrument discrepancy before correction | Corrected relative abundance (%) | Instrument discrepancy after correction | Concentration (pmol/μL) | |||
|---|---|---|---|---|---|---|---|---|
| Q-TOF | Ion trap | Q-TOF | Ion trap | |||||
| 1 | 0.94 ± 0.06 | 2.7 | 2.8 | 0.51 | 0.65 | 1.3 | 1.1 | |
| G2F | 1 | 6.8 ± 0.2 | 14.5 | 2.1 | 4.5 | 4.6 | 1.0 | 8.9 |
| G2S1 | 1 | 26.5 ± 0.9 | 54.5 | 2.1 | 20.2 | 19.1 | 1.1 | 38.4 |
| 2 | 1.6 ± 0.1 | 2.5 | 1.6 | 1.2 | 0.89 | 1.4 | 2.1 | |
| 3 | 0.9 ± 0.1 | ND | 0.7 | ND | 1.3 | |||
| G2S2 | 1 | 100 | 100 | 1.0 | 100 | 100 | 1.0 | 195 |
| 2 | 12.5 ± 0.2 | 13.7 | 1.1 | 12.5 | 13.7 | 1.1 | 25.6 | |
| G3S3 | 1 | 3.8 ± 0.2 | 2.8 | 1.5 | 4.9 | 7.3 | 1.5 | 12.0 |
| 2 | 10.1 ± 0.3 | 4.5 | 2.2 | 13.0 | 11.7 | 1.1 | 24.1 | |
| 3 | 1.56 ± 0.03 | ND | 2 | ND | 3.9 | |||
| G0F | 1 | 8.3 ± 0.6 | 22.1 | 2.7 | 4.4 | 4.8 | 1.1 | 8.9 |
| G1Fa | 1 | 15.6 ± 0.4 | 39.3 | 2.5 | 8.2 | 8.5 | 1.0 | 16.3 |
| G2FS1a | 1 | 6.6 ± 0.1 | 11.4 | 1.7 | 5.7 | 5.9 | 1.0 | 11.4 |
| G2FS2a | 1 | 9.5 ± 0.1 | 6.9 | 1.4 | 10.7 | 10.0 | 1.1 | 20.3 |
Absolute quantification was performed with C13G2S2 as an internal standard with the quadrupole time-of-flight (Q-TOF) instrument
ND not determined
aNot included in equimolar mix. Correction was performed with the “nearest neighbor” rule; for example, G1F values were corrected with the factor for G1.