Handheld device for rapid detection of lead (Pb2+) in gunshot residue for forensic application

Abstract

The present work describes an innovative handheld device for rapid detection of Lead (Pb2+) in Gunshot residues (GSR). Our method is very sensitive, selective and specific for not only qualitative but also quantitative detection of Pb2+ in various GSR samples. It is based on the principle of shift in Light Scattering Plasmon Resonance (LSPR) of Poly Vinyl Alcohol (PVA) Capped Silver Nanoparticles (AgNPs) from 410.5 nm to 590 nm which occur due to strong ion dipole interaction between Pb2+ and PVA capped silver nanoparticles leading to change in color. Various parameters were optimized and characterized using several instruments. Qualitative detection was made visually by naked eyes with a change in color using microliter of samples. Various GSR samples were collected from different ammunition fired at varying range on cloth piece. The results were compared and correlated with standard known methods such as Atomic Absorption Spectroscopy (AAS) and UV–Vis spectroscopy. The method showed linearity in the range from 0.01 to 10 ppm with limit of detection (LOD) of 1.02 ppm (R2 = 0.98). No interfering effect was observed in the presence of several other metal ions such as Cu2+, Mg2+, Ca2+, Ba2+, Hg2+, Cr3+ etc. This low cost, rapid, colorimetric method tested using handheld device for Pb2+ detection in GSR underlines the onsite applicability of this method and helpful in determining the range and type of ammunition used which would further help forensic scientist.