Volume 20, Issue 4 (October 1975)
Firearms Discharge Residue Sample Collection Techniques
Several tests have been employed by law enforcement agencies to demonstrate that an individual has handled or discharged a firearm. With the paraffin test being of doubtful reliability  and the sodium rhodizonate spot test lacking sensitivity , the most commonly used test for firearms discharge residue is the measurement of barium and antimony (Ba and Sb), principally from the primer composition, deposited on the hands during weapon handling or discharge. However, this test is of limited effectiveness, even under optimal conditions. One study  has reported a 15% failure to indicate the presence of residue in a series of test firings. Factors responsible for this inefficiency include variable residue deposition, residue retention, and effectiveness of sample collection. Our study examines several sample collection materials to define a system which will combine high lifting efficiency for gunshot residue components with convenience of use in the field. Until recently, hand lift samples were examined for these two elements primarily by neutron activation analysis (NAA) [4–6]. While NAA affords excellent sensitivity for Ba and Sb, it suffers from long analysis time, high cost, and limited availability of neutron sources. The inherent simplicity and high sensitivity of flameless atomic absorption spectrometry (FAAS) have prompted several investigators to utilize this technique to determine trace quantities of Ba and Sb (and occasionally copper and lead) present in gunshot residues [7–9].