Table 4.
DMA levels (ng/mL) after addition of known amounts of DMAU in blood collected in different tubes from healthy mena
| Incubation time (min) – temperature | DMAU concentration | ||||
|---|---|---|---|---|---|
| 300 ng/mL | 600 ng/mL | ||||
| DMA (ng/mL) | % difference vs. Plainb | DMA (ng/mL) | % difference vs. Plain | ||
| Plain | 30 – 4 °C | 3.3 | 1.5 | ||
| 60 – 4 °C | 5.9 | 4.3 | |||
| 60 – RT | 8.4 | 14.5 | |||
| K2EDTA (1.8 mg/mL) | 30 – 4 °C | 1.4 | −56.1 | 1.2 | −17.1 |
| 60 – 4 °C | 1.4 | −76.5 | 2.3 | −46.4 | |
| 60 – RT | 9.7 | +15.2 | 16.5 | +13.4 | |
| NaF (1.5 mg/mL) + Na2EDTA (3 mg/mL) | 30 – 4 °C | 0.6 | −80.6 | 1 | −30.0 |
| 60 – 4 °C | 1.3 | −77.3 | 2.4 | −43.5 | |
| 60 – RT | LLOQ | – | 10.2 | −29.4 | |
| NaF (5 mg/mL) + K2Oxalate (4 mg/mL) | 30 – 4 °C | LLOQ | – | 0.9 | −38.7 |
| 60 – 4 °C | 1 | −82.2 | 1.2 | −72.7 | |
| 60 – RT | 5.7 | −31.9 | 9.6 | −34.1 | |
| P800 | 30 – 4 °C | 0.7 | −78.1 | 0.9 | −42.5 |
| 60 – 4 °C | 0.9 | −84.2 | 1.4 | −67.1 | |
| 60 – RT | 6.7 | −20.6 | 10.8 | −25.9 | |
a
Note that for the ex vivo spiking studies, 2 mL blood was added to each tube. Thus, the tubes were not filled to their nominal draw volume, so the final NaF concentration does not match the concentration present in the clinical setting (see Table 2). The results from duplicate tubes were averaged.
b
% difference vs. plain—relative difference vs. Plain tube kept at same conditions.