Forensic Ballistics: GSR: SEM-EDX and ICP-MS Quantification

UGC-NET Forensic Science Unit V advanced drill on gunshot residue characterisation, instrumental quantification, and reporting standards. Hard-band coverage on the three-component Pb-Ba-Sb characteristic particle, the two-component Pb-Sb and Ba-Sb consistent category, and the single-element commonly-occurring band under ASTM E1588-20 Standard Practice for Gunshot Residue Analysis by SEM/EDS. Detailed sub-topic drill on backscattered electron imaging for heavy-metal atomic-number contrast, energy-dispersive X-ray spectrometry with Si(Li) and silicon-drift detectors, primer element K-lines and L-lines, peak overlaps (Pb Mα at 2.342 keV with S Kα at 2.307 keV), and the typical 0.5 to 5 micrometre spheroidal-particle band that condensation cooling produces.

The ICP-MS half covers sub-ng/cm² limits of detection for lead, barium and antimony on cotton-swab eluates digested in 0.1 M nitric acid, the 208Pb, 138Ba and 121Sb isotopes commonly monitored, matrix-suppression effects from sodium and the internal-standard selection (rhodium, indium, bismuth). Sample-collection coverage spans adhesive aluminium stubs for SEM and cotton swabs for ICP-MS, hand-versus-face deposition zones, and the six-hour persistence window for the shooter's hands. Lead-free Sintox-primer challenges are drilled on the gallium, titanium, zinc and strontium markers with DDNP base. Calibrated for MSc Forensic Science aspirants targeting Paper II top-decile scores on Unit V.

Topics covered:

• Characteristic, consistent and commonly-occurring GSR particle categories
• SEM backscattered imaging and EDX elemental confirmation
• Particle morphology and the 0.5 to 5 micrometre size band
• ICP-MS quantification with isotope selection and internal standards
• Adhesive stub and cotton swab collection protocols
• Hand, face and clothing deposition zones and persistence dynamics
• Sintox lead-free primer markers and ASTM E1588-20 inclusivity
• ENFSI Guideline for GSR Analysis and reporting categories

A timed self-audit for casework-grade GSR competence. Allow 30 minutes.