Product Overview

Methyl Orange Indicator ACS (CAS No. 547-58-0) is the sodium salt of 4-dimethylaminoazobenzene-4-sulphonic acid, an azo dye recognised as C.I. Acid Orange 52 and C.I. 13025. Protonation of its azo-containing chromophore produces a distinct colour response in the acidic region, enabling visual detection of acid–base endpoints.

The ACS indicator grade is intended for conventional titrimetric and pH-indicator applications where a reproducible visual transition is required. It is particularly suited to titrations involving strong acids and bases and to alkalinity-related procedures in which the endpoint lies within the indicator's acidic transition region.

Typical Applications

• Acid–base titration endpoint indication
• Titration of strong acids with suitable bases
• Alkalinity determinations in aqueous samples
• Preparation of methyl-orange indicator solutions
• Visual pH-transition demonstrations
• Indicator-response verification
• Conventional analytical quality-control procedures

Common Synonyms

• Methyl Orange
• C.I. Acid Orange 52
• C.I. 13025
• Helianthine
• Tropaeolin D
• Sodium p-dimethylaminoazobenzenesulfonate

Storage Conditions

Keep tightly closed and dry, protecting the dye from direct light, moisture and contamination. Preserve clean sampling conditions to maintain colour response and reproducible indicator transition behaviour.