Nitric acid formulations and properties:
- Available as 5% aqueous, 5% alcoholic, 5% nitric in 10% formalin
- Extremely rapid decalcifier
- Preserves cartilage and teeth well
- Slight cellular swelling
- Overexposure (more than 48 hours) impairs nuclear staining
Hydrochloric acid (HCl) formulations and properties:
- Available as 0.5N HCl, 8% HCl with 10% formic acid
- Very rapid and harsh decalcifier
- High concentration and prolonged exposure damages tissue components and impact staining
- Caution: HCl and formaldehyde should never be combined in any way
- Bis-chloromethyl ether forms during a chemical reaction (carcinogen)
- Tissue must be rinsed in water after fixation in formalin before decal in HCl. Then, the HCl must be rinsed off in water before placing it in the tissue processor that uses formalin in processing to avoid chemical reaction and contamination of tissue processor reagents.
