B/B0 Ratio at Standard Curve Endpoint Out of Range
Symptom
The B/B0 ratio (bound/maximum bound) at the lowest or highest standard concentration is either >95% or <5%, indicating the standard curve dynamic range is not properly positioned.
Common Causes
1Standard concentration range does not match assay dynamic range
2Initial standard concentration too high or too low for the antibody affinity
3Improper dilution series calculation for competitive format
Solutions
1Increase or decrease the starting standard amount by one dilution factor
2Shift the entire standard curve to reposition within optimal dynamic range
3Verify standard stock concentration and recalculate dilution series