Buffer Components Inhibit Detection Enzyme (ELISA (Signal Problems))

Question

Accepted Answer

No or very weak signal despite correct antibody binding. Signal loss occurs after addition of detection reagent. Other wells using different buffers show normal signal. Common causes: 1) Sodium azide (commonly 0.02-0.1% in antibody storage buffers) inhibits HRP enzyme activity 2) High concentration of reducing agents (e.g., DTT, β-mercaptoethanol) interferes with enzyme conjugates 3) Buffer pH is outside optimal range for enzyme activity (HRP optimal at pH 5.0-6.0) 4) Chelating agents (e.g., EDTA) remove metal ions required for enzyme function Solutions: 1) Remove sodium azide from all buffers used with HRP-conjugated antibodies; use alternative preservatives 2) Avoid buffers containing reducing agents or chelating agents during detection steps 3) Ensure detection buffer pH is within optimal range: pH 5.0-6.0 for HRP, pH 8.0-9.5 for alkaline phosphatase 4) Use manufacturer-recommended buffers or prepare fresh detection buffers without incompatible reagents