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 serves as a reference in research studies assessing PAH degradation, pollution sources, and ecological risk assessments. Ensures accuracy and traceability in regulatory compliance testing.