Anion exchange chromatography is a process that separates substances based on their charges using an ion-exchange resin containing positively charged groups, such as diethyl-aminoethyl groups (DEAE) 1. In solution, the resin is coated with positively charged counter-ions (cations). Anion exchange resins will bind to negatively charged molecules, displacing the counter-ion. The tightness of the binding between the substance and the resin is based on the strength of the negative charge of the substance 1.

The order of elution of anions in anion exchange chromatography depends on several factors, such as the pH, the ionic strength, and the type of eluent used. Generally, anions with weaker charges or smaller sizes will elute first, while anions with stronger charges or larger sizes will elute later 2. For example, at a pH of 7.5, fluoride (F-) will elute before chloride (Cl-), which will elute before nitrate (NO3-), which will elute before sulfate (SO4 2-) 3. However, this order may change if the pH or the eluent composition is altered.

Some references for more information are:

1: Anion-exchange chromatography - Wikipedia 2: Anion Exchange Chromatography | Bio-Rad 3: METHOD 9056A DETERMINATION OF INORGANIC ANIONS BY ION CHROMATOGRAPHY 4: What Elutes First In Anion Exchange Chromatography

Learn more:

1. en.wikipedia.org2. bio-rad.com3. epa.gov4. theacademy.quest

• Anion-exchange chromatography - Wikipedia: This is an article from the online encyclopedia Wikipedia, which is edited by volunteers. The publisher is the Wikimedia Foundation, and the date of the last revision was April 12, 2023.
• Anion Exchange Chromatography | Bio-Rad: This is a web page from Bio-Rad Laboratories, a company that provides products and services for life science research and clinical diagnostics. The author is not specified, and the date of publication is not given.
• METHOD 9056A DETERMINATION OF INORGANIC ANIONS BY ION CHROMATOGRAPHY: This is a document from the United States Environmental Protection Agency (EPA), which is a federal agency that protects human health and the environment. The author is the Office of Solid Waste and Emergency Response, and the date of publication is December 1996.
• What Elutes First In Anion Exchange Chromatography: This is a web page from Chegg Study, a platform that provides online tutoring and homework help. The author is not specified, and the date of publication is not given.

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