The accelerated polyvinyl-alcohol method for GSR collection--PVAL 2.0

Area of Science:

• Forensic Science
• Analytical Chemistry
• Materials Science

Background:

• The traditional polyvinyl-alcohol (PVAL) collection method for gunshot residue (GSR) is time-consuming (60 min).
• This lengthy procedure limited its application primarily to deceased individuals.
• Distinguishing between suicide and homicide based on GSR patterns was challenging with the older method.

Purpose of the Study:

• To develop and validate an accelerated PVAL collection method (PVAL 2.0).
• To reduce the time required for GSR sample collection.
• To expand the applicability of PVAL collection to live suspects.

Main Methods:

• PVAL 2.0 utilizes a novel 'sandwich technique' involving cotton gauze, a 10% PVAL solution, and a solid PVAL film (Solublon).
• The gauze is molded to the hand and dried using a hairdryer, with traces embedded in water-soluble PVAL.
• The entire collection process is completed within 15 minutes.

Main Results:

• PVAL 2.0 maintains the topographical distribution and maximizes the gain of GSR.
• The method effectively collects other trace evidence like blood and backspatter, unaffected by humidity.
• Crucially, PVAL 2.0 prevents GSR dislocation and contamination, ensuring sample integrity.

Conclusions:

• PVAL 2.0 offers a significantly faster and more efficient method for GSR collection.
• The enhanced technique preserves sample integrity and broadens its forensic application to live subjects.
• This advancement improves the accuracy and speed of firearm use determination in forensic investigations.