Knowledge Base › Troubleshooting Atlas › IHC
DAB chromogen precipitate
What it looks like
DAB chromogen precipitate appears as dark brown granules or spots on the tissue section, which may obscure cellular detail.
Where it usually appears: Typically seen during immunohistochemistry staining when the DAB chromogen is improperly prepared or applied.
Likely causes
- Insufficient mixing of DAB solution
- Expired or improperly stored reagents
- Overreaction time during staining
- Inadequate washing steps after DAB application
- Contamination of reagents
Immediate checks
- Verify DAB reagent expiration dates
- Check for proper mixing of DAB solution
- Inspect washing steps for thoroughness
Corrective action
- Reprepare DAB solution using fresh reagents
- Adjust incubation times according to protocol
- Ensure proper washing after DAB application
Preventive action
- Regularly check reagent expiration and storage conditions
- Standardize mixing procedures for DAB solution
- Implement routine training for staff on IHC techniques
This atlas is for educational purposes for laboratory professionals. It does not replace your institutional SOPs, manufacturer instructions, validated protocols or pathologist judgment. Adapt any action to your laboratory and equipment.
Unimeditrek supports histopathology laboratories with tissue processors, microtomes, staining and workflow equipment plus service and AMC. Talk to a specialist →