Comparative evaluation of chemical segregation methods based on chemical compatibility assessment in chemical laboratories

Chemical laboratories storing diverse chemicals in limited spaces face significant risks from incompatible chemical storage, which can lead to fires, explosions, and toxic gas releases during accidental spills or leaks. Although various institutions have developed their own segregation guidelines, no standardized method exists for quantitatively comparing these approaches or systematically optimizing storage under space constraints. This study develops the Chemical incompatibility Hazard Index (C.H.I.), a novel quantitative metric for evaluating mixed storage risks, and applies it to compare seven international segregation methods. Using the CAMEO (Computer-Aided Management of Emergency Operations) Chemicals database, 52 chemicals from a Korean quantum dot synthesis laboratory were classified according to each method. The seven methods evaluated include the existing Korean regulatory-based approach, systems from Stanford University, Harvard University, Imperial College London, and Fred Hutchinson Cancer Research Center, the Merck classification system, and the National Oceanic and Atmospheric Administration (NOAA) reactive groups. Compatibility charts were generated for each method, and C.H.I. values were calculated based on the proportion of incompatible, caution, and compatible pairwise reactions within each storage group. Among the seven methods, the NOAA reactive group-based approach yielded the lowest average C.H.I. (22.68), significantly outperforming the existing laboratory method (47.78). Subsequent optimization through consolidation of compatible groups to reduce storage locations and selective isolation of six high-reactivity chemicals (11.5 % of inventory) achieved a 71.6 % reduction in average C.H.I. (from 47.78 to 13.56) and a 55.4 % reduction in maximum C.H.I. (from 80.00 to 35.71). This study establishes the first quantitative framework for comparing and optimizing chemical segregation methods. The C.H.I. methodology provides a reproducible approach applicable to diverse laboratory environments, particularly benefiting space-constrained research facilities seeking maximum safety improvement with minimal intervention.