
Thionine Acetate is a cationic phenothiazine dye, essentially the acetate salt form of thionine, historically known as Lauth’s violet after its discoverer, Charles Lauth (1870s). It is widely used as a metachromatic stain in histology and cytology. It selectively stains nucleic acids (DNA/RNA) blue-violet and polysaccharide-rich extracellular matrices (such as cartilage and mucin) in a contrasting red-purple tone.

CAS No.: 78338-22-4
Synonyms: Thionin acetate salt; Thioninacetat; Lauth’s violet
| Physical Properties | |
| Chemical formula | C₁₄H₁₃N₃O₂S |
| IUPAC Name | 3,7-Diaminophenothiazin-5-ium acetate |
| Molecular weight | 287.34 g/mol |
| Solubility | Soluble in water and ethanol |
| Melting Point | Decomposes upon heating,(generally >250 °C) |
| pH | ~6.8 at 20°C (aqueous solution) |
| Chemical Properties | |
| Colour | Dark green to black powder (violet in solution) |
| State | Solid Powder |
| Odor | Odorless |
| λmax | ~600–610 nm (in aqueous solution |
| Pictograms : | ![]() |
| Hazard Statements : | H302 Harmful if swallowed. |
| Precautionary statements : | P264 Wash thoroughly after handling. P301+P312 IF SWALLOWED: Call a POISON CENTER or doctor/physician if P362 Take off contaminated clothing and wash before reuse. |
Thionine Acetate is a cationic phenothiazine dye, essentially the acetate salt form of thionine, historically known as Lauth’s violet after its discoverer, Charles Lauth (1870s). It is widely used as a metachromatic stain in histology and cytology. It selectively stains nucleic acids (DNA/RNA) blue-violet and polysaccharide-rich extracellular matrices (such as cartilage and mucin) in a contrasting red-purple tone.

CAS No.: 78338-22-4
Synonyms: Thionin acetate salt; Thioninacetat; Lauth’s violet
| Physical Properties | |
| Chemical formula | C₁₄H₁₃N₃O₂S |
| IUPAC Name | 3,7-Diaminophenothiazin-5-ium acetate |
| Molecular weight | 287.34 g/mol |
| Solubility | Soluble in water and ethanol |
| Melting Point | Decomposes upon heating,(generally >250 °C) |
| pH | ~6.8 at 20°C (aqueous solution) |
| Chemical Properties | |
| Colour | Dark green to black powder (violet in solution) |
| State | Solid Powder |
| Odor | Odorless |
| λmax | ~600–610 nm (in aqueous solution |
| Pictograms : | ![]() |
| Hazard Statements : | H302 Harmful if swallowed. |
| Precautionary statements : | P264 Wash thoroughly after handling. P301+P312 IF SWALLOWED: Call a POISON CENTER or doctor/physician if P362 Take off contaminated clothing and wash before reuse. |
Thionine is primarily used as a biological stain in microscopy. It is commonly applied to stain cell nuclei and acidic tissue components. It is also used as a redox indicator in analytical chemistry and in some biochemical assays.
Thionine is a basic (cationic) dye belonging to the phenothiazine group. It binds to negatively charged substances such as nucleic acids.
Thionine is a strongly staining metachromatic dye, widely used for biological staining. It can also be used as an alternative to Schiff reagent in certain histochemical procedures, particularly for the demonstration of aldehyde groups and related tissue components.
Thionin is a cationic, metachromatic dye used in histology to stain acidic tissue components, specifically binding to nucleic acids (DNA/RNA) and Nissl substance in neurons.