Used as a pH indicator in analytical chemistry, particularly in colorimetric measurements for determining acidity or alkalinity in solutions. It is commonly employed in environmental testing, such as measuring pH in seawater and other aqueous systems, due to its sharp color change in the pH range of 7.4 to 9.0. The solution transitions from yellow in acidic conditions to purple in alkaline conditions, making it suitable for titrations and monitoring pH changes in biological and chemical processes. Also used in some enzyme activity assays and biochemical research where precise pH detection is required.