Research Article
Simultaneous Quantification of Methotrexate and Its Metabolite 7-Hydroxy-Methotrexate in Human Plasma for Therapeutic Drug Monitoring
Table 4
Stability of MTX and 7-OH-MTX in different conditions (n=5).
| Analyte | Nominal concentration (ng/mL) | three freeze-thaw cycles (RE/%) | Short-term (RE/%) | Long-term (RE/%) | Bench-top (RE/%) |
| MTX | 10 | -5.60 | -5.99 | -2.27 | -0.03 | 500 | 4.02 | 1.56 | -7.29 | 5.10 | 5000 | 4.58 | 4.99 | 6.83 | 8.22 | 7-OH-MTX | 10 | -0.91 | -5.96 | -9.10 | 7.22 | 500 | -8.04 | -8.66 | -12.91 | -0.77 | 5000 | -7.02 | -5.80 | -5.26 | 2.41 |
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