Purification

Purification is the process of removing contaminants from a substance to achieve a higher level of purity. It is used in laboratories, industry, and environmental systems to isolate, concentrate, or render safe a material.

Purification techniques can be physical, chemical, or biological. Physical purification includes filtration, distillation, crystallization, and chromatography. Filtration removes solid particles; distillation separates volatile components by boiling point; crystallization exploits differences in solubility to form pure crystals; chromatography separates components based on differential interactions with a stationary phase. Chemical purification involves reactions or treatments that remove impurities or convert them to separable forms, such as precipitation, acid-base extraction, or oxidation/reduction steps. Biological purification uses organisms or enzymes to degrade contaminants in water, soil, or industrial streams.

Water purification technologies remove contaminants from water to meet safety standards. Steps typically include coagulation and flocculation, sedimentation, filtration, and disinfection. Advanced methods include reverse osmosis and ultraviolet treatment. Purification in pharmaceuticals focuses on removing residual solvents, catalysts, and byproducts from active ingredients, using crystallization, distillation, chromatography, and sterile filtration, with purity validated by assays such as HPLC. Additionally, purification is important in food processing (for example, sugar refining), chemical manufacturing, and environmental remediation (such as activated carbon filtration for air and water).

Purity is quantified by assays expressing the percentage of the target substance, or by impurity profiles; regulatory standards apply in medicine, food, and the environment. In summary, purification is a broad concept involving methods to separate and remove unwanted components to improve quality and safety.