Hochreine

Hochreine is a German term used in science and industry to describe materials with exceptionally high purity. In English-language contexts the term is often translated as high-purity or ultra-pure. It denotes purity levels far above conventional chemical-grade materials and is critical when trace contaminants can affect performance or measurement.

Purity thresholds are context-dependent, and there is no universal standard. Purity is commonly expressed in parts per million, billion, or trillion. In practice, hochreine materials are often described using N-nines, where N equals the number of nines: 5N means 99.999% pure, 6N means 99.9999%. For liquids such as water or solvents, purity can also be indicated by resistivity or by contaminant concentration.

Production and handling: Achieving hochreine quality requires multi-step purification and strict handling. Techniques include distillation, selective crystallization, zone refining, chemical purification, and specialized deposition or purification of solvents. Materials are processed in cleanroom environments and packaged in contaminant-controlled conditions to avoid recontamination.

Measurement and verification: Impurity content is determined with sensitive analytical methods such as ICP-MS, atomic absorption spectroscopy, ion chromatography, or total organic carbon analysis; surface contaminants may be assessed by X-ray photoelectron spectroscopy or secondary ion mass spectrometry.

Applications: Hochreine materials are central to semiconductor fabrication (silicon and compound semiconductors), optical coatings and lasers, high-purity reagents for research and calibration standards, and other high-precision technologies where trace impurities influence performance.