Description

Congo Red CAS NO 573-58-0 is a benzidine-based anionic diazo dye, widely recognized as a vital histochemical stain and a classic pH indicator. Its primary commercial value lies in its unique ability to selectively bind to amyloid fibrils, making it an indispensable diagnostic tool in pathology and biomedical research. This product is essential for laboratories in the biotechnology, pharmaceutical, and academic research sectors, as well as for specialized applications in textile dyeing and as a biological stain.

Application

• Amyloid Detection: The definitive histochemical stain for identifying amyloid deposits in tissue sections (e.g., for diagnosing Alzheimer's disease, systemic amyloidosis).
• pH Indicator: Used as a colorimetric pH indicator, transitioning from blue-violet (pH 3.0) to red (pH 5.0).
• Textile Dyeing: Employed as a direct dye for cotton and other cellulosic fibers, providing a distinctive red color.
• Biological Staining: Used for staining plant cell walls and as a counterstain in various microbiological and cytological procedures.
• Research Reagent: Critical in biochemical research for studying protein aggregation, fibril formation, and dye-binding assays.
• Paper Industry: Occasionally used for coloring paper and in the manufacture of certain inks.

Basic Information

Product Name	Congo Red
CAS No.	573-58-0
Molecular Formula	C32H22N6Na2O6S2
Molecular Weight	696.66 g/mol
Synonyms	Direct Red 28; C.I. 22120; Cotton Red; Congo Red 4B; Congo Red 4BS; Congo Red B; Congo Red C; Sodium 1-naphthalenesulfonate, 3,3'-[(1,1'-biphenyl)-4,4'-diylbis(2,1-diazenediyl)]bis[4-amino-, disodium salt] (IUPAC)
EINECS	209-358-4

Quality Control

Our Congo Red is manufactured under strict quality management systems to ensure batch-to-batch consistency and reliability for critical applications. Each lot undergoes comprehensive analytical testing, including spectrophotometric purity analysis, heavy metal screening, and microbiological testing where applicable. A detailed Certificate of Analysis (COA) confirming identity, purity, and conformance to specification is provided with every shipment.

Storage

Preserve in a tightly closed container, protected from light. Store in a cool, dry, well-ventilated area at a controlled room temperature (15-25°C). Keep away from strong oxidizing agents.

Specification

Item	Specification
Appearance	Brownish-red powder
Identification (IR)	Conforms to structure
Assay (HPLC)	≥ 85% (Dye content)
Loss on Drying	≤ 5.0 %
pH (1% Solution)	7.0 - 9.0
Water Solubility	Freely soluble
Heavy Metals (as Pb)	≤ 20 ppm

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