Eriochrome Black T
|Preferred IUPAC name
|Systematic IUPAC name
Sodium 4-[2-(1-hydroxynaphthalen-2-yl)hydrazin-1-ylidene]-7-nitro-3-oxonaphthalene-1-sulfonate; Solochrome Black T; ET-00
|Molar mass||461.381 g/mol|
|Appearance||dark red/brown powder|
|Acidity (pKa)||6.2, 11.55|
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
Eriochrome Black T is a complexometric indicator that is part of the complexometric titrations, e.g. in the water hardness determination process. It is an azo dye. Eriochrome is a trademark of Huntsman Petrochemical, LLC.
When used as an indicator in an EDTA titration, the characteristic blue end-point is reached when sufficient EDTA is added and the metal ions bound to the indicator are chelated by EDTA, leaving the free indicator molecule.
Eriochrome Black T has also been used to detect the presence of rare earth metals.
- Dubenskaya, L. O. and Levitskaya, G. D. (1999). "Use of eriochrome black T for the polarographic determination of rare-earth metals". Journal of Analytical Chemistry 54 (7): 655–657. ISSN 1061-9348.