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Send EmailNigrosin, Nigrosine, Solvent Black 5, 8005-03-6, 68470-10-6
Nigrosin, Nigrosine, Solvent Black 5, CAS 8005-03-6, 68470-10-6
Nigrosin (CI 50415, Solvent Black 5) is technically a mixture of synthetic, phenazine-derived black dyes. Different forms are used in industry and biology: an alcohol-soluble type (for lacquers and inks) and a sulfonated, water-soluble type (Nigrosin WS, CI 50420, Acid Black 2).
Nigrosin Technical Specifications Table
| Property | Detail |
|---|---|
| Chemical Structure | Mixture of phenazine-derived compounds formed by heating a nitrobenzene + aniline + HCl mixture with copper/iron catalysts |
| CAS Number | 8005-03-6 (Nigrosin) |
| Colour Index (CI) | CI 50415 (Solvent Black 5), CI 50420 (Acid Black 2 – sulfonated form) |
| Molecular Weight | Not fixed due to being a mixture; reported average range of 600–700 g/mol |
| Solubility | Alcohol-soluble type: soluble in organic solvents. Sulfonated type: soluble in water |
| Industrial Use | Lacquers, varnishes, inks, marker pen inks |
| Biological Use | Negative staining (bacterial and fungal capsule detection), Eosin-Nigrosin test (sperm viability analysis) |
| Physical Appearance | Black powder or granules |
| Safety Note | Not suitable for medical use; for industrial and research purposes only |
Key Technical Points
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Negative staining: Does not penetrate the cell membrane, so it stains the background, leaving microorganisms visible as colorless contours.
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Combination with Eosin: Dead cells appear red, live cells colorless; nigrosin provides a dark background.
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Water-soluble form (Nigrosin WS): Preferred in microbiology and biological tests.
Risks and Precautions
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Industrial grade: Not suitable for clinical or food purposes.
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During handling: Gloves, mask, and goggles are recommended; avoid skin contact and inhalation.
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Storage: Store in a dry, cool, dark place away from light.
Nigrosin – Synonyms & Alternative Names
| Category | Name / Code |
|---|---|
| General Trade Names | Nigrosin, Nigrosine |
| Colour Index (CI) | CI 50415 (Solvent Black 5), CI 50420 (Acid Black 2 – sulfonated form) |
| Chemical Descriptors | Phenazine-based dye mixture, Induline-type dye |
| CAS Numbers | 8005-03-6 (Nigrosin), 68470-10-6 (Nigrosin WS) |
| Industrial Codes | Solvent Black 5, Acid Black 2 |
| Laboratory Use | Eosin-Nigrosin stain (combined test), Negative stain dye |
| Other Designations | Water-soluble Nigrosin (Nigrosin WS), Nigrosin Base |
Summary of Synonyms
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Solvent Black 5 → Form soluble in organic solvents.
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Acid Black 2 (Nigrosin WS) → Water-soluble form used in biological staining.
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Induline-type dye → Classified in this group due to its phenazine-derived structure.
Nigrosin – Sector Suitability Table
| Sector | Application Area | Suitability / Standards | Risks / Precautions |
|---|---|---|---|
| Chemical | Lacquers, varnishes, inks, marker pen inks | Compliant with industrial paint and solvent standards | Not suitable for food or medical use |
| Textile | Black pigment prints, special effect dyes | Attention to textile chemical regulations (e.g., REACH, OEKO-TEX) | Limited use in direct-contact textiles; migration tests required |
| Biology / Microbiology | Negative staining, capsule detection, Eosin-Nigrosin test | ISO 17025 lab standards, biosafety rules | Not for clinical diagnosis; only for research and education |
| Food | — | Not suitable | Cannot be used as a food additive |
| Pharmaceutical | — | Not suitable | Not used in drug formulations |
| Research & Education | Microscopy, biology labs | Common in academic use; follow biosafety rules | Low concentrations preferred in student experiments |
Summary
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Industrial use: ✔️ (chemicals, textiles, inks)
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Laboratory use: ✔️ (microbiology, education)
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Food / Pharmaceutical: ❌
