The FA/VB9 (Folic Acid/Vitamin B9) BioAssay? ELISA Kit is a quantitative competitive assay for the detection of Vitamin B12 in serum, plasma, tissue homogenates and other biological fluids. Range: 12.5-800ng/ml Sensitivity: <7.5ng/ml Precision: Intra-assay CV: <8% Inter-assay CV: <10% Assay Principle: This ELISA kit employs the quantitative competitive enzyme-linked immunoassay technique, utilizing a microtiter plate provided in this kit has been pre-coated with an antibody specific to FA/VB9. Standards and samples are added to the appropriate microtiter plate wells followed by a biotin-conjugated antibody specific to FA/VB9. Streptavidin conjugated to Horseradish Peroxidase (HRP) is added to each microplate well and incubated. After TMB substrate solution is added, only those wells that contain FA/VB9, Biotin-conjugated antibody and enzyme-conjugated Streptavidin will exhibit a change in color. The enzyme-substrate reaction is terminated by the addition of sulfuric acid solution and t