1. Aqua Regia

2. Aqua Regia
Materials and Methods: Aqua Regia is a mixture of concentrated nitric acid and hydrochloric acid used clean glassware of trace contaminants.
If a milder reagent can accomplish the same task,
aqua regia is not recommended.
Prepare only the smallest amount needed.
Mix 1 part HNO3 with 3 parts HCl.
In fume hood, add the HNO3 to a glass container. Then add HCl. Gently swirl to mix. Pour acids from smaller containers, not from stock bottles.
Aqua regia should NEVER be taken out of the hood.
Slowly pour or pipet the aqua regia solution into the glassware to be cleaned. Gently swirl or rinse with a flow from a pipet. Allow glassware to soak for several minutes if solids do not readily dissolve.
Hurley, Katie. Haynes Lab SOP, Aqua Regia Use and Neutralization

3. Aqua Regia Waste Disposal Methods Dilution and Neutralization:
Use secondary containment for Aqua Regia waste container that is free from all organic chemicals/solvents.
Dilute used Aqua Regia with water by a factor of 7.5. In a beaker, SLOWLY add the Aqua Regia to the full volume of water. Avoid overheating, and stir solution on a stir-plate.
SLOWLY neutralize by adding sodium bicarbonate solution dropwise. Periodically check the pH with pH paper (aiming for pH 6-9).
Allow solution to cool to room temperature before moving to the waste container, capping the container, or transferring the solution.
Disposal: After the solution has cooled to room temperature, all liquid may be added to the waste container labeled “Neutralized Aqua Regia Waste.”
Hurley, Katie. Haynes Lab SOP, Aqua Regia Use and Neutralization

4. Aqua Regia
Required PPE: Goggles, lab coat, chemical-resistant gloves (18 mm neoprene, Silver Shield, or any other glove rated to protect against hydrochloric AND nitric acid). Face shield and acid-resistant apron are recommended if working with a larger volume (>200ml).
Hazards:
Strong oxidant – Keep away from organics
Corrosive – Wear goggles, thick gloves, lab coat
Acidic – Strong reaction with bases
Off-gassing of toxic fumes
Keep in the hood at all times and never stopper or store.
Hazard Response:
Spill of <200 mL spent solution in hood: soak up with HazMat pads
Spill outside hood or > 200 mL : evacuate and call DEHS
Hurley, Katie. Haynes Lab SOP, Aqua Regia Use and Neutralization