Iodonitrotetrazolium chloride
A chemical that forms a rusty red dye when reduced in lab assays
No single value: Iodonitrotetrazolium chloride is a material, and its colour varies. The background shows its family, red.
Iodonitrotetrazolium chloride, often called INT, is a tetrazolium salt used in laboratory tests. When reduced, it produces a rusty red formazan dye, making it useful for measuring enzyme activity and protein concentration by colour change.
- Turns from colourless to rusty red when reduced
- Used to measure enzyme activity in labs
- Forms a red formazan dye visible to the naked eye
- Toxic to prokaryotes
What colour is Iodonitrotetrazolium chloride?
Iodonitrotetrazolium chloride, or INT, is a synthetic chemical that starts out colourless. When it reacts in certain laboratory tests, it changes to a rusty red colour. This colour change is easy to see and is used to measure how active certain enzymes are. The red dye it forms is called a formazan.
Where does Iodonitrotetrazolium chloride come from?
The name iodonitrotetrazolium chloride comes from its chemical structure, which includes iodine, nitro, and tetrazolium groups. It is not named after a place or person. The compound is made in laboratories and does not occur in nature.
How is Iodonitrotetrazolium chloride made?
INT is made from iodonitrotetrazolium, a synthetic chemical. In the lab, it is usually prepared as a chloride salt. When it is reduced by enzymes like succinate dehydrogenase, INT turns from colourless to a rusty red dye called formazan, which can be measured by its absorbance at 490 nm.
Where Iodonitrotetrazolium chloride is used
This compound is mainly used in scientific research. It acts as an artificial electron acceptor in colour-based tests, known as colorimetric assays. These tests help scientists measure protein concentration and enzyme activity by watching for the colour change to red. The colour change can be seen by eye or measured with lab equipment.
Red around the world
What the red family means from country to country.
The flag uses the four Pan-Arab colours: a red bar at the hoist with green, white and black bands. It was designed by a young Emirati, Abdullah Al Maainah, in 1971.
Politics and protestPrideSource: Flag of the United Arab EmiratesThe flag is a black double-headed eagle on red, the banner of the fifteenth-century hero Skanderbeg. Fans chant Kuq e Zi, red and black.
Politics and protestPrideSource: Flag of AlbaniaArmenian scribes painted manuscripts with vordan karmir, a crimson dye made from an insect that lives on the roots of grasses in the Ararat plain.
Sacred and holySource: Armenian cochinealUnder Juan Manuel de Rosas in the 1830s and 1840s, everyone had to wear a scarlet ribbon to show loyalty to his Federalist party. His enemies, the Unitarians, were tied to sky blue.
Politics and protestFearSource: Juan Manuel de RosasThe flag is red, white and red. Legend says Duke Leopold V's white tunic was soaked in blood at the siege of Acre, all but the band under his belt.
Politics and protestCourageSource: Flag of AustriaRed ochre is used in Aboriginal rock art and ceremony, and is traded over long distances. In the Aboriginal flag the red half stands for the earth and for that ochre.
Sacred and holyNature and renewalAweSource: Australian Aboriginal flagShades and relatives of Iodonitrotetrazolium chloride
INT is similar to other tetrazolium salts, such as tetrazolium chloride. These compounds also change colour when reduced, but may produce different shades or be used in different types of assays.
Questions people ask about Iodonitrotetrazolium chloride
What colour does iodonitrotetrazolium chloride produce?
When reduced in laboratory tests, it produces a rusty red dye called formazan.
Where does the name iodonitrotetrazolium chloride come from?
The name comes from its chemical structure, which includes iodine, nitro, and tetrazolium groups.
What is iodonitrotetrazolium chloride used for?
It is used in scientific assays to measure protein concentration and enzyme activity by colour change.
Is iodonitrotetrazolium chloride natural or synthetic?
It is a synthetic chemical made in laboratories and does not occur naturally.
Good reading and sources
The facts on this page come from the Wikipedia article "INT (chemical)", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). Rang rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.
It may contain mistakes. The swatch is an approximation: named colours are not fixed standards, and every screen shows them a little differently. If something is wrong, tell us. Last refreshed 2026-10-03.
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