Used as a reference standard in environmental testing to quantify the presence of 2,4'-DDD, a metabolite of the pesticide DDT, in soil, water, and biological samples. Commonly employed in gas chromatography (GC) and liquid chromatography-mass spectrometry (LC-MS) analyses to monitor pesticide degradation and assess environmental contamination. Helps laboratories calibrate instruments and validate analytical methods for regulatory compliance and residue analysis in agricultural and ecological studies.