Used primarily as a reference standard in environmental testing laboratories to detect and quantify polychlorinated biphenyl (PCB) contamination in soil, water, and biological samples. Its stable structure allows for reliable calibration in gas chromatography and mass spectrometry analyses. Due to its persistence and toxicity, it is also studied to understand the environmental fate, bioaccumulation, and degradation pathways of chlorinated organic pollutants. Not used in commercial products; strictly for research and monitoring purposes.