What are the two oxidizing agents used in the PAS technique according to the material?

• A. Periodic Acid and Tap Water
• B. Hydrogen Peroxide and Periodic Acid
• C. Sodium Periodate and Water
• D. Potassium Permanganate and Water

Answer: (A)

Periodic acid is the chemical that carries out the oxidation in the PAS reaction, converting vicinal diols in carbohydrates into aldehyde groups. Those aldehydes then react with Schiff reagent to produce the characteristic magenta color of PAS. In the material you’re using, the two oxidizing components listed for the PAS procedure are periodic acid and tap water. Periodic acid provides the true chemical oxidation step, while tap water is included as the second oxidizing component in that source’s protocol, helping to complete the oxidative environment during development and washing steps. This combination explains why those two reagents are described together as oxidizing agents in that material.