Thymolphthalein is commonly used as a pH indicator in various chemical and biological applications. It is particularly useful in titrations to determine the endpoint of acid-base reactions, as it changes color from colorless to blue in the pH range of 9.3 to 10.5. This makes it suitable for detecting the presence of alkaline substances. In educational settings, it is often employed in laboratory experiments to demonstrate pH changes visually. Additionally, thymolphthalein is utilized in some medical diagnostics and research studies to monitor pH levels in biological samples. Its clear and distinct color transition makes it a reliable tool for accurate pH measurement and analysis.