Classifying single fibers based on fluorinated surface treatments

Area of Science:

• Forensic Science
• Analytical Chemistry
• Materials Science

Background:

• Common fiber characteristics limit forensic evidence value.
• Chemical treatments on fibers offer potential for enhanced classification.
• Fluoropolymer coatings provide oil and water repellency but are challenging to detect on single fibers.

Purpose of the Study:

• Investigate fluoropolymer fiber coatings for differentiating fibers.
• Address the analytical challenge of detecting thin surface modifications on single fibers.
• Enhance the evidential value of forensic fiber analysis.

Main Methods:

• Utilized pyrolysis-gas chromatography-mass spectrometry (py-GC-MS) with a novel plasma-assisted reaction chemical ionization (PARCI) source.
• Developed a highly sensitive method for elemental fluorine analysis in pyrolysates.
• Applied py-GC-PARCI-MS for the detection of fluoropolymer coatings on single fibers.

Main Results:

• Successfully detected fluoropolymer coatings on 10-mm single-fiber samples.
• Classified 22 fiber types into 4 distinct groups based on fluorine pyrograms using hierarchical cluster analysis.
• Demonstrated selective and sensitive detection of fluorinated pyrolysates.

Conclusions:

• Fluoropolymer coatings can be detected on single fibers using py-GC-PARCI-MS.
• This technique significantly enhances the classification and evidential value of forensic fibers.
• Highlights the potential of py-GC-PARCI-MS for advanced forensic analyses.