Concentration (μg/mL) | Three freeze-thaw cycles | At ice-water bath for 12 h | At room temperature for 12 h | At 4˚C for 3 days | ||||
RE (%) | RSD (%) | RE (%) | RSD (%) | RE (%) | RSD (%) | RE (%) | RSD (%) | |
0.2 | 13.60 | 0.67 | −5.00 | 5.35 | −44.05 | 21.78 | 5.95 | 3.51 |
1 | −2.76 | 2.13 | 7.63 | 5.69 | −40.03 | 9.36 | 1.78 | 2.74 |
8 | −0.21 | 2.85 | 1.53 | 3.80 | −21.07 | 6.52 | −0.19 | 3.05 |