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How does ion-exchange chromatography separate positively and negatively charged ions?
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chromatography
Overview of the chemical technique of chromatography.
Ion-exchange chromatography separates ions based on their attraction to oppositely charged sites fixed within a stationary phase, typically an ion-exchange resin.21
The separation process relies on the following principles:
- Cation Exchange: Resins containing fixed negative charges (such as sulfonic acid or carboxylic acid groups) attract and bind positively charged ions (cations). These resins are used to separate mixtures of cations.21
- Anion Exchange: Resins containing fixed positive charges (such as quaternary ammonium groups) attract and bind negatively charged ions (anions). These resins are used to separate mixtures of anions.21
As a solution containing a mixture of ions flows through a column packed with these resins, the ions compete for binding sites. Because different ions have varying affinities for the resin, they migrate through the column at different rates. This differential affinity causes the original mixture to resolve into separate bands, allowing for the effective isolation and analysis of individual components.345