Introduction to ethylene diamine tetraacetic acid (EDTA)

April 07, 2023

Edta Acid 99 Jpg

EDTA is a type of polyaminocarboxylic ACID. Its conjugated base is ethylenediaminetetraacetic acid.

EDTA is a colorless compound first synthesized by Ferdinand M ü n in 1935.

EDTA is famous for its chelating properties. It chelates metal ions, such as Ca2+and Fe3+

※ EDTA structural formula

EDTA forms a coordination complex with metal ions. It has six individual electron pairs (two nitrogen atoms and four oxygen atoms) that can participate in the formation of coordination bonds with metal ions (hexagonal ligands).

Most applications of EDTA rely on its ability to chelate metal ions. The metal ions bound to EDTA remain in the solution, but cannot participate in the reaction and have no activity.

※ Since metal ions are necessary for many enzyme catalysis, the presence of EDTA will stop the activity of these enzymes. This is why DNA is stored in a solution containing EDTA.

The anhydrous free acid EDTA is the least soluble in water among all forms of EDTA. In order to dissolve anhydrous free acid EDTA in water, a large amount of NaOH (3.1 ratio) was added to achieve a pH value of 8.0.

Ethylenediaminetetraacetic acid disodium dihydrate has better solubility than anhydrous free acid ethylenediaminetetraacetic acid, and is most commonly used to prepare 0.5M EDTA solution.

EDTA tetrasodium tetrahydrate is soluble in water. The pH value of the obtained solution is higher than 10.0, so it is not suitable for cellular and molecular biology experiments.

In molecular biology laboratories, EDTA is used to prepare many solutions, including TAE, TBE, DNA loaded dyes, resuspension buffer (plasmid separation), Tris EDTA, etc.

Due to the enhanced interaction between cells and cell matrix by divalent metal ions, EDTA has also been added to commonly used cell dissociation reagents, such as trypsin EDTA solution.

EDTA has been widely used in domestic products such as food preservatives and cosmetic stabilizers. It is also widely used to dissolve lime scale. Our daily use products, such as personal care, skin care, processed foods, cosmetic preparations, and cleaning products, typically contain EDTA. It also has a wide range of medical, engineering, agricultural, and industrial applications.

Application of EDTA in Medicine (Chelating Therapy)

a. Eye drops containing EDTA are used to treat calcium deposition in the eyes.

b. EDTA is sometimes used as a ointment to treat skin irritation caused by metals such as chromium, nickel, and copper.

c. EDTA is also used to treat lead poisoning or heavy metal toxicity.

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