Table 2. Results of the five calibration curves for MTXPGs; calibration points (nmol/L)a, slope±SD, intercept and correlation coefficient of the standard curves.
| Compound | C1 | C2 | C3 | C4 | C5 | C6 | Slope (mean±SD) | Intercept (mean±SD) | Correlation coefficient (r) |
| MTXPG1 | 5 (4.5±0.5) | 12.5 (11.3±1.6) | 20 (19.4±0.7) | 40 (38.7±2.4) | 60 (59.9±0.1) | 80 (81.0±1.3) | 187.8±17.9 | −18.9±3.4 | >0.998 |
| MTXPG2 | 5 (4.8±0.6) | 12.5 (11.4±1.7) | 20 (20.5±0.8) | 40 (39.3±1.9) | 60 (60.0±0.1) | 80 (80.4±1.1) | 80.1±11.2 | 49.2±6.1 | >0.999 |
| MTXPG3 | 5 (4.8±0.5) | 12.5 (11.7±1.2) | 20 (20.2±0.5) | 40 (39.9±2.5) | 60 (59.7±0.2) | 80 (80.2±1.4) | 46.4±4.2 | 33.4±3.9 | >0.998 |
| MTXPG4 | 5 (4.4±0.7) | 12.5 (11.2±1.4) | 20 (19.3±1.7) | 40 (39.8±1.6) | 60 (60.1±0.8) | 80 (79.3±0.7) | 30.6±4.4 | 0.52±0.2 | >0.999 |
| MTXPG5 | 5 (4.9±0.5) | 12.5 (12.0±1.5) | 20 (20.4±2.2) | 40 (38.8±3.5) | 60 (59.9±1.2) | 80 (80.6±1.9) | 7.6±1.1 | 17.9±2.7 | >0.995 |
| MTXPGtotal | 10 (10.9±1.8) | 20 (21.8±0.6) | 50 (47.8±1.4) | 100 (90.5±3.7) | 200 (190.9±3.9) | 400 (406.9±2.0) | 25.6±4.9 | −113.9±12.8 | >0.998 |
a
Spiked concentrations of calibration standards [measured concentrations (mean±SD) are shown within brackets].