Eriochrome Black T
Other names: Mordant Black 11, Solochrome Black T, Eriochrome Black T, EBT, 3-hydroxy-4-[(1-hydroxy-2-naphthalenyl)azo]-7-nitro-1-naphthalenesulfonic acid monosodium salt
CAS Number: 1787-61-7
EC Number: 217-250-3
Sum Formula: C20H12N3NaO7S
Molar Mass: 461.38 g/mol
Appearance: dark violet to black powder, often with a green metallic sheen
Eriochrome Black T is a synthetic azo dye and complexometric indicator widely used in analytical chemistry. It is particularly suitable for complexometric titrations involving EDTA and metal ions, especially calcium and magnesium. The dye forms colored complexes with selected metal ions, enabling visual detection of titration endpoints in aqueous systems.
Due to its indicator properties, Eriochrome Black T is commonly used in laboratory procedures for water hardness determination, metal ion detection and analytical method development.
Chemical and Physical Properties:
Form: powder
Color: dark violet to black, often with a green metallic sheen
Solubility in Water: soluble
Solubility in Alcohol: soluble
Solubility in Common Organic Solvents: generally insoluble
Type of Compound: azo dye, hydroxyl-arylazo dye, complexometric indicator
Applications:
Analytical Chemistry:
Used as an indicator in complexometric titrations, particularly in EDTA titrations for calcium and magnesium ions.
Water Hardness Determination:
Applied in laboratory procedures for determining water hardness through metal ion complexation.
Complex Formation:
Forms colored complexes with selected metal ions, supporting quantification and visual endpoint detection.
Dye Chemistry:
May be used in scientific staining, testing and dye-related laboratory applications.
Key Properties:
Complexometric Indicator: suitable for EDTA-based metal ion titrations.
Azo Dye Structure: contains an azo group and aromatic sulfonate structure typical of analytical dyes.
Metal Ion Complexation: forms colored complexes with calcium, magnesium and other metal ions.
Distinctive Color: supplied as a dark violet to black powder, often with a green metallic sheen.
Storage:
Store in a tightly closed container in a cool, dry and well-ventilated place.
Protect from moisture, contamination and direct sunlight.
Keep away from strong oxidizing agents and incompatible materials.
Handling:
Avoid formation and inhalation of dust.
Use in a well-ventilated area.
Avoid contact with eyes.
Prevent release to the environment.
Use appropriate personal protective equipment, including protective gloves, eye protection and a dust mask when dust may be generated.
This product is intended strictly for technical, laboratory and research use. It is not intended for consumption, medical, pharmaceutical, cosmetic or feed applications.