Used as a mixed pH indicator in titrations, particularly in the analysis of total alkalinity in water and wastewater. The combination provides a sharp color change from green to red around pH 4.5, making it ideal for detecting the endpoint in strong acid-strong base titrations. Commonly employed in environmental labs and industrial quality control for carbonate and bicarbonate determinations. Also used in microbiology as part of certain culture media to monitor pH changes during fermentation processes.