The B/B0 ratio (bound/maximum bound signal) for the highest or lowest standard concentration exceeds 95% or falls below 5%, indicating the standard curve dynamic range does not adequately cover the analyte concentration range.
Common Causes
1Standard curve range not optimally positioned for the competitive assay format
2Highest standard concentration too low (B/B0 >95%)
3Highest standard concentration too high (B/B0 <5%)
4Improper standard dilution series preparation
Solutions
1Increase the standard concentration by one dilution factor if B/B0 >95% at curve endpoint
2Decrease the standard concentration by one dilution factor if B/B0 <5% at curve endpoint
3Verify proper pipetting and serial dilution technique for standard preparation
4Adjust the concentration range to position curve endpoints between 5-95% B/B0