When performing the Schiff staining method lipids are oxidized by:

• A. Performic acid and peracetic acid
• B. Hydrogen peroxide
• C. Ozone
• D. Nitric acid

Answer: (A)

Schiff staining relies on aldehyde groups to generate the magenta color, so lipids must be oxidized to form those aldehydes before the Schiff reagent can react. The reagents used for this lipid oxidation are performic acid and peracetic acid, which are potent, controlled oxidants that introduce aldehyde groups into lipid molecules without destroying tissue structure. Hydrogen peroxide alone doesn’t reliably create the needed aldehydes in this context, and ozone or nitric acid are not used here because they cause excessive or nonspecific oxidation and damage, not the selective aldehyde formation required for this stain.