More typical lab extractions transfer organic compounds out of an aqueous phase and into an organic phase. The distribution of a solute between two phases is an equilibrium condition described as partitioning. Chromatography Chromatography is a separations method that relies on differences in partitioning behavior between a flowing mobile phase and a stationary phase to separate the components in a mixture. A column holds the stationary phase and the mobile phase carries the sample through it. Sample components that partition strongly into the stationary phase spend a greater amount of time in the column and are separated from components that stay predominantly in the mobile phase and pass through the column faster.
Gas chromatography is a chromatographic technique for separating volatile compounds.
A gas chromatograph consists of a flowing mobile phase, an injection port, a separation column containing the stationary phase, and a detector. Compounds injected into the flowing mobile phase separate as they pass through the column due to differences in their partitioning behavior between the mobile gas phase and the stationary phase in the column. Mobile phases are generally inert gases such as helium, argon, or nitrogen. The injection port consists of a rubber septum through which a syringe needle is inserted to inject the sample. The injection port is maintained at a higher temperture than the boiling point of the least volatile component in the sample mixture.