eluate

Eluate is the liquid that emerges from a separation process, typically carrying the components that have been washed out of a solid or stationary phase. The term derives from elute, meaning to wash out. In chromatography, eluate refers to the effluent that exits the column, consisting of the mobile phase plus solutes that have interacted with the stationary phase. The eluate is often collected in fractions for subsequent analysis or purification, and its composition depends on factors such as the mobile phase, flow rate, column chemistry, and the properties of the analytes.

In solid-phase extraction and related sample-preparation techniques, eluate describes the liquid that contains the target analytes after they have been desorbed from the sorbent by an eluting solvent. In this context, the eluate is the sample to be analyzed, while the sorbent remains after elution. Elution can be achieved with solvents of varying strength to optimize recovery and purity.

Other uses include electrophoresis or capillary methods and forensic toxicology, where an eluate is the solution recovered from a cartridge or matrix after rinsing with solvent. The term is sometimes used more generally to denote any liquid that has been eluted from a solid material. Practical work with eluates often involves detection and quantification by techniques such as UV-Vis, mass spectrometry, or NMR.