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.

The interaction between the anti-Ractopamine (Rac) monoclonal antibody and the Rac derivation immobilized on the sensor chip surface was studied with surface plasmon resonance (SPR) biosensor. A continuous detection method based on the linear response during the association phase was developed. The sensor chip surface was regenerated after several tests performed continuously, thus the detection step was simplified and the life span of the chip was prospected to be prolonged. The detection was performed as an inhibitive immunoassay. The mixture of anti-Rac monoclonal antibody and the sample flowed over the surface with Rac derivation was immobilized. The relative response was in inversely proportion to the concentration of Rac. The detection limit was less than 4 μg/L with a detection time of 15 min.