Jonfritt

Jonfritt is a term used in Scandinavian languages to describe a substance, typically a liquid, from which dissolved ions have been removed. In practice, jonfritt vatten refers to deionized or ion-free water with very low concentrations of dissolved minerals and salts. The removal of ions reduces electrical conductivity and mineral content, making the water highly pure for laboratory, industrial and pharmaceutical use.

Production methods commonly used to achieve jonfritt water include ion exchange, distillation, reverse osmosis followed by polishing, and electro-deionization. Ion exchange is typical, using a cation exchange resin in its hydrogen form and an anion exchange resin in hydroxide form; when used in sequence or in a mixed bed, these resins remove most ionic species. Pretreatment to remove organics and particulates and to control alkalinity is usually required.

Applications for jonfritt water span analytical chemistry, semiconductor fabrication, pharmaceutical manufacturing, and high-precision rinsing, where ionic impurities can interfere with processes, measurements or product quality. It is also used in cooling circuits, autoclaves and other systems where mineral buildup must be avoided.

Quality and standards are monitored by measuring electrical conductivity or resistivity, with higher resistivity indicating lower ion content. Common laboratory grades aim for resistivity around 1 MΩ·cm to 18.2 MΩ·cm at 25°C. Additional metrics such as total organic carbon, microbial counts and particulate levels are often specified to ensure purity. See also deionized water and ultrapure water.