Dünnschichtchromatographie

Dünnschichtchromatographie, often abbreviated TLC, is a planar chromatography technique used for the separation and analysis of components in a mixture. It relies on a thin stationary phase coated on a flat support—commonly silica gel, alumina, or cellulose on glass, aluminum, or plastic—combined with a volatile solvent or solvent mixture as the mobile phase. Components separate based on differences in polarity and their interactions with the stationary phase versus the mobile phase.

In a typical TLC setup, a small sample spot is applied near one end of the plate. The plate is then placed in a closed development chamber containing a shallow layer of solvent. Capillary action moves the solvent up the plate, and the sample components travel at different rates, producing distinct spots. After drying, spots are often visualized under UV light or with chemical stains. The retention factor (Rf), defined as the distance moved by a component divided by the distance moved by the solvent front, is used to identify and compare substances.

Applications of TLC include qualitative analysis, fingerprinting of mixtures, monitoring of reaction progress, and rapid purity checks. It can also be scaled up to preparative TLC for isolating larger amounts of individual components. Advantages of TLC are its simplicity, low cost, speed, and minimal sample requirements. Limitations include relatively lower resolution compared with high-performance techniques and semi-quantitative rather than precise quantification. TLC is widely used in organic chemistry, biochemistry, and pharmaceuticals, and has a high-performance variant known as HPTLC (high-performance thin-layer chromatography) that enhances resolution and throughput.