Description

Tetrasodium 4,4'-Bis[[p-[(p-Sulphonatophenyl)Azo]Phenyl]-N,N,o-Azoxy]Stilbene-2,2'-Disulphonate is a high-purity, water-soluble fluorescent whitening agent (FWA) belonging to the stilbene derivative class. This compound is engineered to absorb ultraviolet light and re-emit it as visible blue light, effectively counteracting yellowing and enhancing the perceived whiteness and brightness of materials. It is a critical additive for manufacturers in the textile, paper, detergent, and plastics industries seeking to achieve superior optical brightening effects and improve product aesthetics.

Application

• Textile Finishing: Primary application for whitening and brightening cotton, nylon, wool, and synthetic fibers during scouring, bleaching, or finishing baths.
• Paper Manufacturing: Incorporated into pulp or coating formulations to produce high-brightness printing, writing, and specialty papers.
• Laundry Detergents & Fabric Softeners: A key optical brightener in household and industrial detergent powders and liquids to maintain fabric whiteness over multiple washes.
• Plastics and Polymers: Used to brighten white plastics (e.g., PVC, polyolefins) and synthetic fibers, compensating for inherent yellowness.
• Soaps and Personal Care: Added to certain soaps and cosmetic formulations to enhance visual appeal.
• Coatings and Paints: Employed in specific coating systems to improve brightness and opacity.

Basic Information

Product Name	Tetrasodium 4,4'-Bis[[p-[(p-Sulphonatophenyl)Azo]Phenyl]-N,N,o-Azoxy]Stilbene-2,2'-Disulphonate
CAS No.	32651-66-4
Molecular Formula	C~46~H~28~N~6~Na~4~O~16~S~4~
Molecular Weight	1153.0 g/mol (approx.)
Synonyms	Fluorescent Brightener 220; Tinopal CBS-X; Blankophor BSU; FWA 220; 4,4'-Bis[[4-[(4-Sulfophenyl)azo]phenyl]amino]stilbene-2,2'-disulfonic acid tetrasodium salt; 2,2'-(1,2-Ethenediyl)bis[5-[[4-[(4-sulfophenyl)azo]phenyl]amino]benzenesulfonic acid] tetrasodium salt; Optical Brightener OB-1 (for plastics); Tetrasodium 2,2'-(1,2-ethenediyl)bis[5-[[4-[(4-sulfophenyl)azo]phenyl]amino]benzenesulfonate]
EINECS	251-164-6

Quality Control

Our production of Tetrasodium 4,4'-Bis[[p-[(p-Sulphonatophenyl)Azo]Phenyl]-N,N,o-Azoxy]Stilbene-2,2'-Disulphonate adheres to stringent quality management systems. Every batch is subjected to comprehensive analytical testing, including HPLC for purity and assay, spectrophotometry for strength and shade, and checks for insolubles and heavy metals. Certificates of Analysis (COA) detailing batch-specific results are provided to ensure traceability and compliance with your technical requirements.

Storage

Preserve in a tightly closed container, protected from light. Store in a cool, dry, and well-ventilated area at room temperature (15-25°C). This material is hygroscopic (moisture-sensitive); the original container must be kept tightly sealed after use to prevent absorption of atmospheric moisture, which can affect performance.

Specification

Item	Specification
Appearance	Yellowish to light brown powder
Identification (IR)	Conforms to structure
Assay (HPLC)	≥ 95.0%
Strength (Spectrophotometry)	100 ± 3% (vs. Standard)
Moisture (Karl Fischer)	≤ 5.0%
Water Solubility	Clear solution at 1%
pH (1% Solution)	7.0 - 9.0
Heavy Metals (as Pb)	≤ 20 ppm

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