Used in environmental testing to calibrate analytical instruments for detecting polycyclic aromatic hydrocarbons (PAHs) in soil, water, and air samples. Commonly applied in gas chromatography (GC) and high-performance liquid chromatography (HPLC) to quantify phenanthrene levels in industrial effluents and contaminated sites. Also used in research to study PAH degradation, toxicity, and their impact on ecosystems. Ensures accurate measurement in regulatory compliance and pollution monitoring programs.