Chromatography is a valuable technique that is used to separate mixtures of compounds. It can be used as a means of purification, such as an isolating a single component of a mixture, or for sample analysis. Chromatographic analysis can tell us how many components are in a mixture, how a sample compares with a known standard, or even how much of each component is present. Common types of chromatography include thin layer chromatography, or TLC, column chromatography, GC, or gas chromatography, and HPLC, which stands for high pressure or high performance liquid chromatography. Each of these methods follows the same basic principles.