2.5.3 Precision and accuracy
Intra-day, inter-day precision were evaluated by analyzing QCs (n=5) at low, medium and high concentrations (10 ng/mL, 400 ng/mL, 800 ng/mL) on the same day or 3 different days respectively. The precision was defined as the relative standard deviation (RSD) of QC sample concentrations determined at 5 replicates. The accuracy was assessed as the percentage to the nominal concentration (%) by analyzing 5 repetitive QCs at each concentration. The mean values should be within 15% of the nominal value except low concentration, which should not deviate more than 20%.