TABLE 1.
Summary of method validation results.
| Criteria | 3‐HG | 2‐HG | GA |
|---|---|---|---|
| Limit of quantification (LOQ) | 1 μmol/L | 5 μmol/L | 6 μmol/L |
| Linearity (r 2)—0 to 400 μmol/L (3‐HG 0–100 μmol/L) | 0.996 | 0.992 | 0.995 |
| Measurement range limits | 1–500 μmol/L a | 5–1000 μmol/L a | 6–1000 μmol/L a |
| Precision (intra‐batch) b | |||
| Low value | 13.3% | 6.4% | 3.5% |
| High value | 5.5% | 4.2% | 5.3% |
| Precision (inter‐day) c | |||
| Low value | 10.2% | 13.7% | 14.0% |
| High value | 14.3% | 13.8% | 14.5% |
| Accuracy | 84% | 85% | 97% |
| Recovery d | |||
| Low value | 85% | 97% | 82% |
| Medium value | 91% | 113% | 102% |
| High value | 97% | 116% | 116% |
Note: Accuracy was evaluated using samples from a quantitative external quality program (ERNDIM).
a
Highest tested concentration.
b
Low value 3 μM (3‐HG), 20 μM (2‐HG), 10 μM (GA). High value 200 μM for all three acids. Results expressed as relative standard deviation (RSD%).
c
Low value 5 μM (3‐HG), 27 μM (2‐HG), 14 μM (GA). High value 124 μM (3‐HG), 190 μM (2‐HG), 216 μM (GA). Results expressed as relative standard deviation (RSD%).
d
Low value 5 μM (3‐HG), 10 μM (2‐HG and GA). Median value 40 μM (3‐HG), 80 μM (2‐HG and GA). High value 100 μM (3‐HG), 200 μM (2‐HG and GA).