Phenolphthalein

Phenolphthalein (CAS 77-09-8) is a pH-sensitive indicator compound that transitions from colorless to vivid pink-red under alkaline conditions. This makes it a standard tool in titration and analytical chemistry.

In industrial settings, it functions as a colorimetric marker for detecting alkalinity in substrates, coatings, and treated surfaces. In the printing and packaging industry, indicator solutions are used to test paper substrates.

These tests ensure compatibility with inks and adhesives during the manufacturing process. Textile and leather processors apply it to verify the pH of dye baths, wash liquors, and various finishing treatments.

This verification is critical where residual alkali affects product quality. In concrete and construction material testing, it is the standard reagent for carbonation depth assessment on cut surfaces.

Sprayed solutions reveal the boundary between carbonated and uncarbonated zones. Personal care formulators use it as a bench-level QC tool to confirm the alkalinity of cream, soap, and hair relaxer formulations.

This ensures safety and consistency during development and production. The product is supplied as a white to pale yellow crystalline powder available in reagent-grade and ACS-grade specifications.

These grades are suited to laboratory and analytical applications, as well as technical grade for industrial process use. Pre-prepared indicator solutions at standard concentrations are also commercially available.