Table 5. Wet and Dry Stability Study of PVLs and Creatinine in Urine Extract by LDTD-MS/MSa.
| analyte | stability test | condition | nominal concentration (μg/L) | mean concentration (μg/L) | precision (% CV) | accuracy (%) |
|---|---|---|---|---|---|---|
| 3-HPVL (191 → 106) | WS (QC-L) | 1 week at 4 °C | 150 | 155.2 | 4.7 | 103.5 |
| WS (QC-M) | 1250 | 1329.1 | 5.9 | 106.3 | ||
| WS (QC-H) | 2250 | 2520.8 | 1.7 | 112.0 | ||
| DS (QC-L) | 1 h at room temperature | 150 | 149.6 | 5.5 | 99.7 | |
| DS (QC-M) | 1250 | 1325.3 | 4.9 | 106.0 | ||
| DS (QC-H) | 2250 | 2410.5 | 3.8 | 107.1 | ||
| 3,4-DHPVL (207 → 163) | WS (QC-L) | 1 week at 4 °C | 472 | 430.4 | 6.5 | 91.2 |
| WS (QC-M) | 2672 | 2548.5 | 7.8 | 95.4 | ||
| WS (QC-H) | 4672 | 5396.0 | 9.0 | 115.5 | ||
| DS (QC-L) | 1 h at room temperature | 472 | 472.1 | 2.4 | 100.0 | |
| DS (QC-M) | 2672 | 2522.7 | 3.0 | 94.4 | ||
| DS (QC-H) | 4672 | 4469.1 | 7.7 | 95.7 | ||
| creatinine (114 → 86) | WS (QC-L) | 1 week at 4 °C | 300 | 291.5 | 7.1 | 97.2 |
| WS (QC-M) | 1200 | 1229.5 | 4.6 | 102.5 | ||
| WS (QC-H) | 3000 | 3015.8 | 5.0 | 100.5 | ||
| DS (QC-L) | 1 h at room temperature | 300 | 300.6 | 8.1 | 100.2 | |
| DS (QC-M) | 1200 | 1178.5 | 3.0 | 98.2 | ||
| DS (QC-H) | 3000 | 2979.2 | 3.3 | 99.3 | ||
a
Wet stability was abbreviated to WS and dry stability to DS.