Chromatographs are used to perform chromatographic separation and produce chromatograms. Chromatography separates complex mixtures of chemicals or proteins into their various constituents. A chromatograph takes a chemical mixture carried by a liquid or gas and separates it into its component parts as a result of the differential distribution of the solutes as they flow around or over a stationary liquid or solid phase. The basic principal of chromatographs is that when a stream of chemical compounds flows over a surface that attracts some of the compounds more than others, the less strongly attracted compounds move faster than the compounds that stick more tightly to the surface, and the mixture becomes separated. Most chromatographs consist of five different parts: the mobile phase supply system, the injection or sampling system, the column and column oven, the detector, and the data acquisition and data processing system.

There are two basic types of chromatographs: liquid chromatographs and gas chromatographs. A liquid chromatograph is used to separate ions or molecules that are dissolved in a solvent. If a sample solution contacts a second solid or liquid phase, the different solutes interact with the other phase to differing degrees due to differences in adsorption, ion-exchange, partitioning, or size. These differences allow the mixture components to be separated by using the differences to determine the transit time of the solutes through a column. A gas chromatograph can be used to identify air pollutants or chemicals based on volatility and/or evaporation. For example, researchers in the fragrance industry can use a gas chromatograph mass spectrometer to identify the chemicals that make up a particular odor or taste. The gas chromatograph separates the chemical mixture into pulses of pure chemicals. The mass spectrometer identifies and quantifies the chemicals.

Chromatographs are used in a variety of industries and applications such as the drug discovery industry, organic and inorganic chemistry, and the food industry. A gas chromatograph is often used for determine the nutritional quality and safety of food. For best results, chromatographs must provide fast data acquisition speeds with high resolution/exact mass measurements. A chromatograph must also feature a high dynamic range for both qualitative and quantitative analysis.