A chemometrically validated, field-portable wet-chemical protocol for rapid triage of 15 white powder substances.

Reliable field identification of unknown white powder substances is a persistent analytical challenge in security screening, forensic science, and environmental emergency response. We report an eight-step sequential chemical protocol that generates fourteen orthogonal descriptors for the rapid, kit-based, instrument-free triage of fifteen common white powder substances spanning organic materials (wheat flour, starch, sucrose, urea, monosodium glutamate, baking powder) and inorganic compounds (NaCl, alum, (NH4)2SO4, CaCO3, Na2CO3, Ca(OH)2, NaOH, bleaching powder, CaC2). The protocol operates within a compact portable kit (30 × 20 × 10 cm; <50 USD) and completes identification within 15-20 min without electricity or specialised instrumentation. Principal component analysis (PCA) resolved all fifteen substances into four chemically coherent clusters, capturing 63.5% of total variance in two components. The fifteen substances yield fifteen distinct descriptor profiles that a transparent decision rule separates without overlap under the controlled conditions examined. The transparent decision rule resolves all fifteen substances using nine of the fourteen descriptors, and feature-importance analysis identifies aqueous pH (step 3) as the dominant discriminator. The protocol provides a low-cost analytical workflow with strong potential for field triage, demonstrated on a representative panel of substances frequently encountered in operational casework; positive identifications are provisional and intended for triage rather than confirmatory analysis.