What is elrich test?

The Elrich test is a colorimetric test used to detect the presence of indole compounds, such as tryptophan and indole-3-acetic acid (a plant hormone), in a given substance. It is named after its inventor, Paul Ehrlich, a German physician and scientist. The test involves adding a few drops of a mixture of concentrated sulfuric acid and sodium nitrite to the substance being tested, and then observing the resulting color change. If the substance contains indole compounds, it will turn a deep red or purple color, indicating a positive result for indole. The Elrich test is commonly used in microbiology to identify certain bacteria that produce indole, as well as in biochemistry and organic chemistry research. However, it is important to note that the Elrich test is not specific to indole compounds and can produce false positives with other substances that contain certain chemical groups or structures.