Variables | Candidate reference materials | |||||
---|---|---|---|---|---|---|
L1 | L2 | L3 | L4 | L5 | L6 | |
uchar (%) | 1.2 | 5.9 | 3.9 | 6.8 | 2.8 | 5.8 |
ubb (%) | 0.8 | 0.5 | 0.7 | 0.2 | 0.7 | 0.9 |
ults (%) | 0.8 | 2.5 | 1.2 | 1.9 | 2.8 | 3.6 |
uWHO (%) | 2.4 | 2.4 | 2.4 | 2.4 | 2.4 | 2.4 |
Relative standard uncertainty uc (%) | 2.9 | 6.9 | 4.8 | 7.5 | 4.7 | 7.3 |
Relative expanded uncertainty, 2× uc (%) | 5.9 | 13.7 | 9.7 | 14.9 | 9.4 | 14.6 |
Expanded uncertainty (µg/L) | 0.7 | 3.7 | 8.1 | 18.9 | 21.9 | 97.3 |
Assigned value (µg/L) | 12.0 | 27.0 | 84.2 | 126.0 | 232.2 | 666.4 |
Abbreviations: AFP, alpha-fetoprotein; BCCL, Beijing Center for Clinical Laboratories; Can-RM, candidate reference material; uchar, uncertainty of the measurement; ubb, uncertainty from homogeneity of the material; ults, uncertainty due to the long-term stability; uWHO, uncertainty of WHO standard materials; uc, combined standard uncertainty.
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