Table 3.
LC-MS/MS method performance of retention, linearity, sensitivity, precision, limit of detection, and limit of quantification for glucosamine, galactosamine, and muramic acid.
| Analyte | m/z transition | t r (min) | Linearitya | Sensitivityb | Prec. L/Hc (%) | LODd (μM) | LOQe (μM) |
|---|---|---|---|---|---|---|---|
| Glucosamine | 180 > 72 | 4.41 ± 0.04 | 0.9997 | 3.8E4 ± 0.33E4 | 1.3/1.0 | 0.025 | 0.07 |
| Glucosamine | 180 > 84 | 4.41 ± 0.04 | 0.9997 | 2.1E4 ± 0.17E4 | 0.8/0.7 | 0.05 | 0.2 |
| Galactosamine | 180 > 72 | 4.52 ± 0.03 | 0.9999 | 8.1E4 ± 0.78E4 | 0.3/0.7 | 0.01 | 0.03 |
| Galactosamine | 180 > 84 | 4.52 ± 0.03 | 0.9997 | 3.8E3 ± 0.38E3 | 1.8∗/1.5 | 0.5 | 1.2 |
| Muramic acid | 252 > 126 | 2.01 ± 0.01 | 0.9994 | 5.1E4 ± 0.20E4 | 1.0/0.6 | 0.01 | 0.03 |
aPearson correlation coefficient (r) determined for seven points, ranging from LOQ to 40 μM (n = 6).
bRegression slope expressed in area units (counts)/μM (n = 5).
cPrecision expressed as relative standard deviation (RSD) for repeated injections at 1 μM (L) and 10 μM (H) (n = 8).
dLimit of detection reported as the injected concentration giving a peak height corresponding to three times the baseline noise level.
eLimit of quantification reported as the injected concentration giving a peak height corresponding to ten times the baseline noise level.
∗Precision at low level was investigated at a concentration of 2 μM for the 180 > 84 transition of galactosamine, due to its relatively high LOD.