Thin‐Layer Chromatography

Abstract

AbstractIn thin‐layer chromatography (TLC), the sample solution is applied as a spot or band on the origin of the layer spread on a support (the plate). After evaporation of the sample solvent, the plate is placed in a sealed chamber containing a solvent chosen as the mobile phase. Development occurs as the mobile phase moves through the layer, and the components of the sample move at different rates to create the separation. The plate is removed from the chamber, and the separated zones are detected by physical or chemical methods, identified by comparison of their migration to standard zones on the same plate, and quantified by visual or instrumental methods based on measurement of zone sizes and intensities. A great variety of compounds can be separated, including organic, inorganic, biological, and chiral. Environmental, pharmaceutical, biomedical, and food samples are among the sample types commonly analyzed by TLC. Advantages of TLC include rapid analysis time because many samples can be analyzed simultaneously, low solvent usage on a per‐sample basis, a high degree of accuracy and precision for instrumental TLC, and sensitivity in the nanogram or picogram range. Coupling of TLC with other analytical methods such as high‐performance liquid chromatography (HPLC), mass spectrometry (MS), and Fourier transform infrared spectrometry (FTIR) provides enhanced opportunities for sample analysis. Disadvantages of TLC include application to only nonvolatile compounds, limited resolution capability (separation numbers or peak capacities of 10–50), and the absence of fully automated systems, although the individual steps of the technique can be automated.