| Added conc (ng∙mL−1) | Calculated conc (ng∙mL−1) | % CV | % Relative error | |||
| Intra day | Inter day | Intra day | Inter day | Intra day | Inter day | |
| 15 | 14.91 | 14.89 | 14.84 | 14.82 | 0.8 | −1.6 |
| 4750 | 4748.2 | 2743.6 | 5.2 | 4.3 | −2.4 | −0.9 |
| 9500 | 9501.4 | 9493.6 | 4.1 | 2.8 | 0.8 | −1.4 |