Table 1. Within-day and between-day accuracy and imprecision for MTX at three levels of QC samples

Concentrations of QC samples (μg/mL)	Found mean concentrations ± SD (μg/mL)	Between-day (n=4) Accuracy/imprecision (%)	Within-day (n=5) Accuracy/imprecision (%)
0.5	0,494 ± 0,016	98.84/3.42	92.4/7.50
10	9,857 ± 0,660	98.57/6.69	99.2/6.00
20	19,615 ± 1,593	89.07/8.12	98.3/6.05