New trends and approaches in the voltammetric analysis of gunshot residue

Gunshot residue (GSR) analysis remains a central technique of firearm-related forensic investigations; however, the current gold-standard technique, scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM-EDS), is constrained by high cost, limited portability, and laboratory dependence. These limitations have driven increasing interest in electrochemical and voltammetric approaches as rapid, cost-effective, and field-deployable alternatives capable of detecting both inorganic (IGSR) and organic (OGSR) components. This review examines developments reported between 2000 and 2026, with particular emphasis on nanomaterial-modified screen-printed electrodes, advanced voltammetric techniques (including square-wave and differential pulse anodic stripping voltammetry), and their application to the simultaneous determination of key metallic markers (Pb, Sb, Ba) and organic compounds such as nitroglycerin, nitrocellulose, and diphenylamine. Emerging strategies involving microfluidic integration, hybrid electrochemical-optical platforms, and chemometric data analysis are also evaluated in the context of improving sensitivity, selectivity, and on-site applicability. Importantly, this review extends beyond analytical performance by situating current methodologies within a probabilistic evidence-evaluation framework based on likelihood ratios and Bayesian inference, an aspect largely overlooked in prior literature. Persistent challenges, including matrix interferences, electrode fouling, and the lack of standardized forensic validation protocols, are discussed alongside the requirements for reliable operational deployment.