Description

Mordant Red 21 is a synthetic, water-soluble azo dye primarily used as a mordant dye for textiles and as a biological stain. Its core value lies in its ability to form stable, colored complexes with metal ions like aluminum, chromium, and iron, resulting in vibrant and wash-fast shades on natural fibers. This compound is essential for manufacturers and laboratories requiring a reliable red colorant for dyeing wool, silk, and leather, as well as for histological staining applications in microscopy.

Application

• Primary application as a mordant dye for wool, silk, and leather, producing red to violet shades with excellent light and wash fastness.
• Use as a biological stain in histology and microscopy, particularly for staining cytoplasmic elements and specific tissue structures.
• Coloration of paper and specialty inks where metal complexation is desired for stability.
• Potential use as a colorimetric indicator or reagent in analytical chemistry laboratories.
• Dyeing of anodized aluminum and other metal surfaces for decorative or identification purposes.
• Educational and research applications in textile chemistry and dye synthesis studies.

Basic Information

Product Name	Mordant Red 21
CAS No.	6417-36-3
Molecular Formula	C15H9N2NaO5S
Molecular Weight	352.30 g/mol
Synonyms	Acid Alizarin Red GG; Alizarin Red GG; Alizarin Red S Extra; Alizarin Red GG Sodium Salt; Alizarin Sulphonated Sodium Salt; Mordant Red 21 (C.I. 58005); C.I. Mordant Red 21; Sodium Alizarinsulfonate
EINECS	229-127-2

Quality Control

Our Mordant Red 21 is manufactured under a stringent quality management system to ensure batch-to-batch consistency and performance. Each lot is tested against key parameters including dye content, shade, solubility, and fastness properties. A comprehensive Certificate of Analysis (COA) detailing purity, heavy metal content, and other relevant specifications 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 room temperature (15-25°C). Keep away from strong oxidizing agents. The product is light-sensitive (store away from light).

Specification

Item	Specification
Appearance	Reddish-brown to orange powder
Identification (IR)	Conforms to structure
Assay (Dye Content)	Min. 85%
Solubility in Water	Completely soluble
pH (1% Solution)	6.0 - 8.0
Moisture Content	Max. 5.0%
Heavy Metals (as Pb)	Max. 20 ppm
Ash Content	Max. 1.0%

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