Methyl orange in ACS Reagent grade water 85% (dye content), Sigma-Aldrich®

Supplier: SIGMA-ALDRICH MICROSCOPY
Danger

Synonyms: 4-((4-(Dimethylamino)phenyl)diazenyl)benzenesulphonic acid, sodium salt, Methyl orange sodium salt, Helianthine

M-Clarity™ quality level = MQ200

114510-25G 114510-100G 114510-500G
114510-25GEA 21.8 GBP
114510-25G 114510-100G 114510-500G
Methyl orange in ACS Reagent grade water 85% (dye content), Sigma-Aldrich®
Methyl orange

Methyl orange (C.I. 13025) is the sodium salt of p-dimethylaminoazobenzenesulfonic acid. It is an orange-colored synthetic dye, which changes color depending on the pH of the solution. It develops a red color in acidic solution and yellow color in basic solution.


  • Methyl orange is used as a:
  • pH indicator in the cell sap
  • Counterstain to crystal violet in staining pollen tubes
  • Component of a polychrome histological stain
  • Solution indicator, such as in assays of oxalic and malonic acids
  • In other biomedical applications that include use in film dosimeters and as a reagent for the assay of bromide ions

Formula: C₁₄H₁₄N₃NaO₃S
MW: 327,34 g/mol
Boiling Pt: ∼90 °C (1013 hPa)
Melting Pt: > 300 °C
Density: ∼1 g/cm³ (20 °C)
Flash Pt: 38 °C
Storage Temperature: Ambient
MDL Number: MFCD00007502
CAS Number: 547-58-0
EINECS: 208-925-3
UN: 3143
ADR: 6.1,III
Merck Index: 13,06127
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Specification Test Results

Appearance (colour) Orange
Appearance (form) Powder
Infrared spectrum Conforms to structure
Visual interval, pH 3.0 pink or red Pass
Visual interval, pH 3.2 pinkish orange Pass
Visual interval, pH 4.4 yellow Pass
Appearance (clarity) Pass
Carbon 43.7 - 59.1%
Nitrogen 10.9 - 14.8%

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