Integrated Multispectroscopic Identification of Organophosphorus and Triazine Pesticide Mixtures via DFT–Spectroscopy‐Integrated Identification Method (D‐SIIM)

The identification of unknown chemical agents in mixtures remains a critical challenge in chemical safety and forensic science. In this study, we extend the density functional theory–spectroscopy‐integrated identification method (D‐SIIM) to organophosphorus and triazine‐class pesticide mixtures—the most structurally complex targets addressed by this framework to date. Six pesticide compounds featuring multiring heterocyclic architectures with diverse heteroatoms were analyzed using gas chromatography–mass spectrometry (GC–MS), infrared (IR), Raman, and nuclear magnetic resonance (NMR) spectroscopy, combined with quantum chemical calculations. GC–MS library screening was reproducible for chlorpyrifos, phosalone, and atrazine, which were assigned at match qualities of 94–99 in every mixture containing them, but not for the thermally labile azinphos‐methyl, whose quality ranged from 38 to 91 across mixtures analyzed under identical conditions. Because such an outcome cannot be anticipated for a sample of unknown composition, library screening alone provides no dependable basis for identification. In contrast, the integrated D‐SIIM approach—cross‐validating experimental IR, Raman, and NMR spectra against density functional theory (DFT)‐predicted values—successfully identified every component of each mixture, from binary through quaternary systems. Validated now across nerve agent simulants, designer drug stimulants, and pesticides, D‐SIIM offers a library‐independent identification platform for chemical safety and security.