B/B0 Ratio at Curve Endpoint Outside 5-95% Range

Symptom

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.

1. 1 Standard curve range not optimally positioned for the competitive assay format
2. 2 Highest standard concentration too low (B/B0 >95%)
3. 3 Highest standard concentration too high (B/B0 <5%)
4. 4 Improper standard dilution series preparation

1. 1 Increase the standard concentration by one dilution factor if B/B0 >95% at curve endpoint
2. 2 Decrease the standard concentration by one dilution factor if B/B0 <5% at curve endpoint
3. 3 Verify proper pipetting and serial dilution technique for standard preparation
4. 4 Adjust the concentration range to position curve endpoints between 5-95% B/B0