ABSTRACT
Objective To prepare and evaluate the reference materials for plasma von Willebrand Factor antigen testing with fresh frozen plasma.Methods The candidates were prepared by low temperature centrifugation in 5 different concentration levels.The homogeneity and stability of the preparation was evaluated according to the ISO Guide35 and CNAS-GL03.The comparability between STAGO and IL system was evaluated according to the WS/T 356-2011.Then the preparations were characterized by six laboratories with the Secondary Coagulation Standard established by NIBSC(SSCLOT4).Results Homogeneity evaluation of the preparation showed that there was no statistically significant difference between the groups (P >0.05),the F values of factor analysis of variance were 0.317~0.844,the uncertainty range was 1.01% ~2.06%.A linear regression based on stability evaluation indicated that the linear trend (within 24 weeks)was insignificant (P >0.05). The uncertainty range of long-term (within 24 weeks)stability was 0.79% ~ 1.20%.The results of the preparations on STAGO and IL system were comparable.The certificated values of the candidates were range from 12.2% to 138.9% with uncertainties were 0.06%~0.09%,respectively.The range of combined standard uncertainty was 0.03% ~ 0.16% while the expanded uncertainty was 2.2%~6.7%.Conclusion The reference materials for von Willebrand Factor antigen testing were stable and homogenous with comparability between STAGO and IL.The method of characterization was accurate and reliable.