Used in environmental and industrial laboratories for calibration of analytical instruments to measure phenol levels in water, wastewater, and soil samples. Ensures accurate detection of phenolic compounds, which are toxic and regulated pollutants. Commonly applied in quality control for pharmaceutical, chemical, and petrochemical industries where phenol is a raw material or byproduct. Also used in validation of test methods such as spectrophotometry, HPLC, and GC-MS for compliance with regulatory standards like EPA and ISO.