elute

Elute is a verb meaning to wash out soluble substances from a material by percolating a liquid through it. In laboratory practice, the resulting liquid is often referred to as the eluate, while the process itself is called elution. The term is widely used in analytical chemistry, biochemistry, and related fields.

In chromatography, elution describes the movement of components through a stationary phase under the influence of a mobile phase. The solvent or solvent mixture that drives this process is called the eluent. Components interact differently with the stationary phase, leading to separation as they travel at different speeds. Elution can be carried out under isocratic conditions (constant composition of the eluent) or with a gradient (varying solvent strength), altering retention times and separation quality. Key concepts include elution volume, retention time, and elution strength.

Elution is also central to other separation techniques, such as solid-phase extraction, where a bound analyte is released from a solid sorbent using a suitable eluent, and ion-exchange or affinity chromatography, where changes in pH, ionic strength, or competing agents are used to displace the target molecule from the stationary phase.

In practice, the choice of eluent depends on the chemistry of the analyte and the matrix, aiming to maximize recovery and resolution while minimizing co-elution of interfering substances. The concept is also encountered in broader contexts of leaching and purification, where liquids remove soluble components from solids.