Table 5.
Long term stability and freeze-thaw stability of matrix-matched quality control samples (n = 5)
| Analyte | Long- term stability (% difference) after 180 days |
Freeze-thaw stability (cycles) |
||
|---|---|---|---|---|
| 10 ng/mL | 300 ng/mL | 10 ng/mL | 300 ng/mL | |
| Neopterin | -7.0 | -8.7 | 2 | 2 |
| Tryptophan | 3.0 | -6.6 | 2 | 3 |
| Kynurenine | -9.6 | -1.4 | 3 | 3 |
| Kynurenic acid | -6.02 | 8.78 | 2 | 2 |
| 3-hydroxykynurenine | 4.3 | -11.6 | 2 | 2 |
| Xanthurenic acid | 1.7 | 5.6 | 1 | 1 |
| Anthranilic acid | 10.1 | 7.9 | 2 | 2 |
| 3-hydroxyanthranilic acid | 1.0 | 2.9 | 1 | 2 |
| Quinolinic acid | -6.7 | 3.7 | 3 | 3 |
| Picolinic acid | 10.1 | 7.9 | 2 | 2 |
| Arginine | 6.9 | -3.6 | 1 | 2 |
| Citrulline | 0.4 | -10.7 | 2 | 3 |
| Methylhistamine | 9.9 | 13.3 | 1 | 1 |