Description

Eriochrome Black A is a high-purity metallochromic indicator dye, widely recognized for its critical role in complexometric titrations. Its primary value lies in providing a sharp, clear color change endpoint for the precise determination of metal ions such as calcium, magnesium, and zinc in aqueous solutions. This compound is essential for quality control and analytical laboratories across diverse sectors, including water treatment, pharmaceuticals, and industrial chemical manufacturing, where accurate metal ion quantification is paramount.

Application

• Complexometric Titration Indicator: The primary application is as a visual endpoint indicator for EDTA titrations of alkaline earth metals and other divalent cations.
• Water Hardness Analysis: Critical for determining total hardness (calcium and magnesium concentration) in potable, industrial, and wastewater.
• Pharmaceutical QC Testing: Used in the assay of raw materials and finished products containing magnesium, calcium, or other relevant metal ions.
• Industrial Process Control: Monitors metal ion concentrations in chemical manufacturing, plating baths, and boiler feed water.
• Educational & Research Laboratories: A standard reagent for teaching analytical chemistry principles and for research involving metal-ligand interactions.
• Dyeing & Staining Agent: Finds use in specific histological staining procedures and as a colorant in specialized applications.

Basic Information

Product Name	Eriochrome Black A
CAS No.	3618-58-4
Molecular Formula	C20H12N3O7SNa
Molecular Weight	461.38 g/mol
Synonyms	Solochrome Black A; Mordant Black 1; Chrome Blue Black R; Acid Chrome Blue Black; CI 15710; CI Mordant Black 1; 3-Hydroxy-4-[(2-hydroxy-1-naphthyl)azo]-7-nitro-1-naphthalenesulfonic Acid Sodium Salt; 1-Naphthalenesulfonic acid, 3-hydroxy-4-((2-hydroxy-1-naphthalenyl)azo)-7-nitro-, monosodium salt
EINECS	222-819-2

Quality Control

Our Eriochrome Black A is manufactured under strict quality management systems to ensure batch-to-batch consistency and reliability for analytical applications. Each lot undergoes comprehensive testing, including identification (IR), purity assay (HPLC/Titration), and checks for relevant impurities. A Certificate of Analysis (COA) detailing all test results is provided with every shipment to support your quality assurance protocols.

Storage

Preserve in a tightly closed container, protected from light. Store in a cool, dry, well-ventilated area at controlled room temperature (15-25°C). Keep away from heat and incompatible materials. The product is light-sensitive and should be stored away from light to maintain stability.

Specification

Item	Specification
Appearance	Dark brown to black powder
Identification (IR)	Conforms to reference spectrum
Assay (Dye Content)	Min. 85%
Loss on Drying	≤ 5.0%
Solubility (in Water)	Completely soluble, yielding a clear red-violet solution
Transition pH Range	Approx. 7.3 - 11.5 (Wine red to blue)
Heavy Metals (as Pb)	≤ 20 ppm

Note: Specifications can be tailored. Please contact us for the detailed technical data sheet of a specific grade.