ANS:A - elution

Elution is a process used in various separation techniques, particularly chromatography, to separate components of a mixture based on their different affinities for a mobile phase (usually a solvent) and a stationary phase. The term "elution" comes from the Latin word "eluere," meaning "to wash out" or "to remove." Here's how elution typically works in chromatography:

1. Column Setup: In chromatography, a column is packed with a stationary phase, which can be a solid material (as in column chromatography) or a gel (as in gel chromatography). The stationary phase is chosen based on its ability to interact with the components of the mixture being separated.
2. Sample Application: The mixture to be separated (the sample) is applied to the top of the column. It is then allowed to interact with the stationary phase.
3. Mobile Phase: A mobile phase, usually a solvent or a solvent mixture, is continuously passed through the column. The components of the sample will have varying affinities for the stationary phase and the mobile phase.
4. Separation: As the mobile phase flows through the column, the components of the sample are carried along with it. Components that have a higher affinity for the stationary phase will interact more strongly with it and will move more slowly through the column. Conversely, components with a higher affinity for the mobile phase will move more quickly through the column.
5. Elution: The process of selectively washing out or removing the components from the stationary phase by the mobile phase is referred to as elution. As the mobile phase carries the components down the column, they are eventually eluted from the column, one by one, based on their differing interactions with the stationary phase.
6. Detection and Collection: As each component elutes from the column, it can be detected using various detection methods (such as UV-Vis spectroscopy, fluorescence detection, or mass spectrometry) and collected for further analysis or use.