- A solution of nitrohydrochloric acid known as aqua regia (Latin for “Royal Water”).
- A 3:1 blend of hydrochloric(HCl) acid and nitric acid is used in the conventional solution (HNO3).
- It’s often used in microfabrication and microelectronics labs to remove precious metals like gold, platinum, and palladium from substrates. Glassware can also be washed with aqua regia to remove only trace amounts of organic contaminants. To avoid explosions or skin burns, aqua regia solutions should be handled with extreme caution.