Quinaldine Red is primarily used as a pH indicator in various biochemical and analytical applications. It is effective in the pH range of 1.4 to 3.2, where it transitions from colorless to red, making it useful for determining acidity in solutions. In biological research, it is employed to study enzyme activity and protein interactions, particularly in environments requiring precise pH control. Additionally, it is utilized in histology for staining tissues to enhance microscopic visualization. Quinaldine Red is also applied in environmental testing to monitor pH changes in water samples, aiding in the assessment of water quality. Its ability to act as a fluorescent dye makes it valuable in fluorescence microscopy for labeling and tracking cellular components.