Elution vs. Adsorption

The Engineer's Perspective
The Engineer's Perspective

Table of Contents

Elution vs Adsorption

Elution and adsorption are both surface phenomena and are applied as separation techniques to remove a substance from its source.

Elution is the process of removing or extracting one material from another by washing the analyte with a solvent whereas adsorption is the uptake of a substance by the surface of a solid material due to intermolecular attraction between them. 

Key Takeaways

  • Elution and adsorption are both separation techniques that differin how they separate substances — adsorption uses surface affinity, while elution uses solubility.
  • Adsorption separates a substance from its bulk phase by attaching to a solid surface to where it has affinity with.
  • Elution separates a substance adhering to the solid surface by constantly dissolving it with a solvent.
  • Adsorption is commonly applied in petroleum, pharmaceutical, and wastewater treatment processes, while elution is suitable in lab-scale industries, such as in the field of medicine.

How Does Adsorption Work?

Adsorption is a rate-based separation technique that is largely dependent on factors like temperature, pressure, and pH. The main factor of the adsorption process, however, is the nature of the adsorbent being used. The fundamentals of adsorption lies on the surface affinity between the adsorbate and adsorbent. 

Adsorbents are characterized by high porosity and have rough surfaces implying a larger surface area for adsorption. Silica gel, zeolites, and activated carbons are the common adsorbents used due to their high surface area. 

Elution Technique In Adsorption Column Chromatography

Both sorption processes, elution and adsorption are closely associated together in adsorption column chromatography. It is a chromatographic process using a solid/adsorbent as a stationary phase and a mobile phase that is either a gas or liquid. Here’s how the elution technique works:

Elution vs Adsorption Elution Technique In Adsorption Column Chromatography
Source: Wikipedia

During adsorption, the adsorbent adsorbs a specific analyte as it passes through the column. The elution technique is used to remove the analyte by running the column with a solvent (called “eluent”). The solvent either passes by the adsorbent/analyte complex or displaces the analyte by binding to the adsorbent. The solvent which isolates the analyte (called the “eluate”) from the bulk material goes out the column. 

Applications of Elution

One particular application of the elution process is in medicine. Elution is commonly used to concentrate and solubilize antibodies from red blood cells (RBCs) for subsequent identification studies.

In this case, the eluent is acidic glycine which removes the antibodies from the red blood cells. While the eluate is the supernatant fluid (antibodies-containing solvent) which is further filtered out through centrifugation. Finally, the antibodies are then tested 

Final Thoughts

Although elution is often associated with adsorption, the two must be well distinguished from one another by how they separate mixtures. In summary:

  • Adsorption applications are more versatile — from small-scale capillary tubes to large-scale adsorption towers. It is often used in chemical industries to remove contaminants by the binding of adsorbate to the surface of an adsorbent. 
  • Elution is more applicable to lab-scale techniques, most commonly in the field of  medicine.


Why is an elution test done?

In medicine, an elution test is performed to separate antibodies from the cells in order to examine these antibodies for possible disease identification studies. 

Who used the adsorption elution technique the first time?

Siracusa used the adsorption-elution technique for the first time for medical applications. He is a forensic scientist that used the absorption-elution technique in 1923 for the ABO blood group typing of bloodstains.

What is adsorption in blood banking?

Adsorption is used in blood banking to bind antibodies to red blood cells in order to remove them from the plasma and analyze them.


  1. Blood Bank Guy. “Glossary: Elution.” Blood Bank Guy, https://www.bbguy.org. Accessed 29 October 2022.
  2. Jobson, Megan. “Absorption (chemistry).” 17 January 2022, https://www.tau.ac.il. Accessed 29 October 2022.
  3. “Physisorption and Chemisorption – Definition, Mechanism, Differences.” Byju’s, https://byjus.com. Accessed 29 October 2022.
  4. Ramnarayan, B. K., et al. “ABO blood grouping from hard and soft tissues of teeth by modified absorption-elution technique.” J Forensic Dent Sci., vol. 5, no. 1, 2013, pp. 28-34. Accessed 3 November 2022.

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