Citric acid 20 %, consisting of water and citric acid (C6H8O7), is used as a solution in metallography and in scientific laboratories. As an etchant and reducing agent additive, it enables the fine processing of metal surfaces. Its ability to passivate stainless steel is particularly noteworthy, helping to increase the corrosion resistance of the material.

Citric acid 20 % is also used in the production of sodium citrate buffer pH 7.0, an important component of staining kits in laboratories. It helps to regulate the pH value and stabilize proteins.

The properties of citric acid 20 %, a weak organic acid, make these versatile applications possible. The proton donors of the carboxyl groups interact with metal surfaces and proteins, leading to the desired chemical reactions.