Tropical Weathering Effects on Neat Gasoline: An Analytical Study of Volatile Organic Profiles

Gasoline is the most common ignitable liquid used to initiate fires, making its detection and identification in fire debris crucial for determining incendiary origins. Fire debris is typically collected after extinguishment and safety clearance, often resulting in gasoline weathering, especially when delayed. Most research on gasoline weathering has been conducted in controlled laboratory settings in temperate climates. However, the effects of tropical conditions on the rate of gasoline weathering and the resulting chemical composition of volatiles remain largely unexplored. Understanding how tropical environmental factors alter gasoline weathering is essential for accurate fire debris interpretation in such regions. This study investigates how tropical climates impact gasoline weathering indoors and outdoors. Weathered samples were prepared by volume reduction method, gradually evaporating gasoline from 10% to 95%. Indoor samples were exposed to room temperature, while outdoor samples were left in open space under natural tropical conditions. Gas Chromatography/Mass Spectrometry (GC-MS) analysis revealed chromatographic shifts in heavier compounds (C3–C4 alkylbenzenes) compared to lighter ones like toluene as weathering progressed. Correlation between indoor and outdoor samples was high (>0.970) at 10–50% weathering but declined (<0.600) at 90–95%, indicating differing patterns. All target compounds remained detectable across all samples.