Inanalytical andorganic chemistry,elution is the process of extracting one material from another by washing with a solvent: washing of loadedion-exchange resins to remove capturedions, or elutingproteins or otherbiopolymers from anelectrophoresis orchromatography column.

In a liquidchromatography experiment, for example, ananalyte is generally adsorbed by ("bound to") anadsorbent in a liquid chromatography column. The adsorbent, a solid phase, called a "stationary phase", is a powder which is coated onto a solid support. Based on an adsorbent's composition, it can have varyingaffinities to "hold onto" other molecules—forming a thin film on the surface of its particles. Elution then is the process of removing analytes from the adsorbent by running a solvent, called aneluent, past the adsorbent–analyte complex. As the solvent molecules "elute", or travel down through the chromatography column, they can either pass by the adsorbent–analyte complex or displace the analyte by binding to the adsorbent in its place. After the solvent molecules displace the analyte, the analyte can be carried out of the column for analysis. This is why as the mobile phase, called aneluate, passes out of the column, it typically flows into adetector or is collected by a fraction collector for compositional analysis.

Predicting and controlling the order of elution is a key aspect of column chromatographic and column electrophoretic methods.

Aneluotropic series is listing of various compounds in order of eluting power for a givenadsorbent. The "eluting power" of asolvent is largely a measure of how well the solvent can "pull" ananalyte off the adsorbent to which it is attached. This often happens when the eluent adsorbs onto the stationary phase, displacing the analyte. Such series are useful for determining necessary solvents needed forchromatography of chemical compounds. Normally such a series progresses from non-polar solvents, such asn-hexane, to polar solvents such asethanol,methanol orwater. The order of solvents in an eluotropic series depends both on thestationary phase as well as on the compound used to determine the order.

Theeluent oreluant is the "carrier" portion of the mobile phase. It moves the analytes through thechromatograph. Inliquid chromatography, the eluent is the liquid solvent; ingas chromatography, it is the carrier gas.^[1]

Theeluate contains theanalyte material that emerges from thechromatograph. It specifically includes both the analytes and coeluting solutes passing through the column, while the eluent is only the carrier.

The "elution time" of a solute is the time between the start of the separation (the time at which the solute enters the column) and the time at which the solute elutes. In the same way, theelution volume is the volume of eluent required to cause elution. The elution volume may be enough information to identify solutes under standard conditions for a known mix of solutes in a certain technique. For instance, a mixture ofamino acids may be separated byion-exchange chromatography. Under a particular set of conditions, the amino acids will elute in the same order and at the same elution volume.

Antibody elution is the process of removing antibodies that are attached to their targets, such as the surface ofred blood cells. Techniques include using heat, a freeze-thaw cycle, ultrasound, acids or organic solvents. No single method is best in all situations.^[2]

• Chromatography
• Desorption
• Electroelution
• Gradient elution in high performance liquid chromatography
• Leaching

• Brown, Phillis (2001).Advances in chromatography.CRC Press. p. 36.ISBN 0-8247-0509-2.

• Chemistry glossary
• Eluotropic seriesArchived 2015-12-22 at theWayback Machine

• Analytical chemistry
• Chromatography

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