Ekstraktio

Ekstraktio, or extraction, is a separation process in which a solute is transferred from a feed mixture into a second solvent. The driving force is the difference in solubility or affinity of components between phases. In practice, a target compound moves from one phase into another until an equilibrium is reached. The efficiency depends on solvent choice, temperature, contact area, and mixing.

There are two main branches: liquid-liquid extraction and solid-liquid extraction. In liquid-liquid extraction, two immiscible liquids are contacted; the solute distributes according to a partition coefficient. In solid-liquid extraction, a solid material is treated with a solvent to dissolve the desired compounds, followed by separation of liquid and solid. Techniques include maceration, percolation, and Soxhlet extraction, which provides continuous solvent contact with a solid over extended periods. Other approaches include pressurized liquid extraction, ultrasound-assisted extraction, and, for volatile compounds, steam distillation or supercritical CO2 extraction.

Applications cover natural products, pharmaceuticals, and environmental analysis. Ekstraktio is used to isolate essential oils, caffeine from coffee, polyphenols from plants, flavors and fragrances, and active pharmaceutical ingredients. It is also used to remove contaminants or to concentrate analytes for testing.

Key considerations include solvent polarity and selectivity, safety and toxicity, cost, and environmental impact. Green chemistry aims to reduce solvent use and employ safer solvents or alternative methods. Limitations can include incomplete transfer, degradation of heat-sensitive compounds, and the need for downstream purification. Overall, ekstraktio remains a foundational technique in chemistry, natural product research, and industry.