SOP templates for Aqua Regia and Piranha Solution


Does your research require the use of Aqua regia or Piranha solutions? These are two types of acidic washes used for very specific purposes and have very important workplace health and safety considerations. 

Aqua regia is a combination of two strong acids, hydrochloric acid and nitric acid, which react to form an incredibly acidic solution, stronger than the sum of its parts. Aqua regia can dissolve many metals that are normally very challenging to dissolve, such as platinum, silver and gold. These metals are known as noble metals, so the solution that could dissolve them was given the title “royal water,” aqua regia in Latin.

Piranha solutions are a mixture of concentrated sulfuric acid with hydrogen peroxide, usually in a ratio between 3:1 to 7:1. They are used to remove trace amounts of organic residues from substrates. The mixing procedure is an exothermic reaction that can reach temperatures of 100⁰C or higher. Because Piranha solutions are highly corrosive and oxidizing mixtures, they react violently with organic material and can cause an explosion.

The potential health and safety hazards of strong corrosives coming into contact with your eye or skin include severe burns. Personal protective equipment worn should be specified in your lab SOP and include appropriate chemical-resistant gloves, eye protection and a laboratory coat.  

Aqua regia and Piranha solutions should never be stored in closed containers, as gas evolution can lead to pressure build-up and an explosion. For more information on how to handle these solutions safely in your laboratory, review the new standard operating procedure (SOP) templates now available for Aqua Regia and Acid Piranha solution on the Chemical SOPs page.

All personnel must be trained on the potential hazards and safe work practices of these solutions including being trained on the lab’s SOP prior to working with them.

For assistance with any of your laboratory’s chemical or process SOPs, contact