A two-stage near-infrared framework for screening and quantification of trace soil hexachlorocyclohexane under strong matrix interference.

Hexachlorocyclohexane (HCH) is a persistent legacy pesticide whose presence in soils threatens environmental quality and food-chain safety. Although near-infrared (NIR) spectroscopy is attractive for high-throughput, reagent-free soil analysis, its application to trace HCH remains challenged by weak analyte-related signals and their strong overlap with variable soil-matrix absorption and scattering. These conditions destabilize direct concentration modeling and, in practical datasets, are further aggravated by a substantial fraction of samples reported as