Copper Determination in Gunshot Residue by Cyclic Voltammetric and Inductive Coupled Plasma-Optical Emission Spectroscopy

Abstract

Abstract. Analysis of gunshot residue (GSR) is a crucial evidences for a forensic analyst in the fastest way. GSR analysis insists a suitable method provides a relatively simple, rapid and precise information on the spot at the crime scene. Therefore, the analysis of Cu(II) in GSR using cyclic voltammetry (CV) on screen printed carbon electrode (SPCE) is a better choice compared to previous alternative methods such as Inductive Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) those required a long time for analysis. SPCE is specially designed to handle with microvolumes of sample such as GSR sample. It gives advantages for identification of copper in GSR on-site preliminary test to prevent the sample loss on the process to be analyzed in the laboratory. SPCE was swabbed directly on the shooter's arm immediately after firing and acetate buffer was dropped on SPCE before CV analysis. For ICP-OES analysis, cotton that had been soaked in 0.5 M nitric acid was swabbed on the shooter's arm immediately after firing and kept in a tightly closed sampling tube. Gold coated SPCE that had been through nanoparticles modification exhibits excellent performance on voltammograms. The calibration was linear from 1 to 50 ppm of copper, the limit of detection for copper was 0.3 ppm and a relative standard deviation was 6.1 %. The method was successfully applied to the determination of copper in GSR. The Cu determination on SPCE was compared and validated by ICP-OES method with 94 % accuracy.

Toward Locard’s Exchange Principle: Recent Developments in Forensic Trace Evidence Analysis

“…Electrochemical methods were also used in a study by Hashim et al., in which they used cyclic voltammetry with a screen printed carbon electrode to detect Cu­(II) in GSR . They compared their results to those obtained using inductively coupled plasma optical emission spectroscopy (ICP-OES).…”

Recent Advances in Voltammetric Sensing

“…It can tolerate constant mechanical stress without losing its attractiveness, a low-cost way for conducting onsite crime scene investigations in a range of forensic settings [143]. Hashim et al 2016 reported gold modified screen printed electrode for Cu (II) analysis in GSR using CV (Figure 9). It was also compared with ICP-OES analysis with 94% accuracy [144].…”