Color intensity varies significantly between wells that should be identical. Pattern may show edge effects, gradients across the plate, or random spotty appearance indicating incomplete or inconsistent reagent contact.
Common Causes
1Incomplete washing with wells not fully filling with wash buffer or incomplete aspiration
2Wells not completely aspirated between steps, leaving variable residual volumes
3Plates stacked during incubations causing temperature gradients
4Poor mixing of reagents leading to concentration gradients
Solutions
1Ensure all wells completely fill with wash buffer and are fully aspirated; use automated plate washer if available
2Completely aspirate wells between each step; verify pipette and washer function
3Keep plates separated during incubation if not using plate rotator; avoid incubation near heat sources
4Thoroughly mix all reagents before dispensing; use multichannel pipettes or reagent reservoirs for uniform distribution