What is a common application of thin layer chromatography (TLC)?

Thin layer chromatography (TLC) is commonly utilized for separating mixtures of organic compounds due to its ability to provide rapid results and require only small sample sizes. In TLC, the mixture is applied to a thin layer of stationary phase, typically a silica gel or alumina, on a flat surface. When a suitable solvent (the mobile phase) travels up the plate through capillary action, the different components of the mixture move at different rates based on their affinity for the stationary phase versus the mobile phase. This differential movement allows for the separation of the compounds, which can then be visualized, often through staining or UV light, enabling identification and analysis of the individual components.

The other choices involve techniques better suited for more complex biological analyses or measurements that are not aligned with the primary purpose of TLC. Identifying DNA structures typically requires methods like gel electrophoresis or sequencing, while determining protein structures often involves techniques such as X-ray crystallography or nuclear magnetic resonance (NMR) spectroscopy. Measuring pH levels involves the use of pH meters or indicators, which is unrelated to chromatographic techniques.