Forensic Analysis of Polymeric Carpet Fibers Using Direct Analysis in Real Time Coupled to an AccuTOF™ Mass...

Area of Science:

• Forensic Science
• Analytical Chemistry
• Materials Science

Background:

• Polymeric fibers, particularly carpet fibers, are frequently found as trace evidence at crime scenes.
• Accurate identification of these fibers is crucial for forensic investigations.
• Common carpet fiber types include nylons, polyesters, and olefins.

Purpose of the Study:

• To evaluate the effectiveness of Direct Analysis in Real Time (DART™) coupled with an Accurate time-of-flight (AccuTOF™) mass spectrometer (MS) for forensic carpet fiber analysis.
• To optimize DART-MS parameters for differentiating between major polymer types and sub-classes.
• To validate the DART-AccuTOF™ method against established techniques like Fourier-transform infrared spectroscopy (FTIR).

Main Methods:

• Optimization of DART gas temperature, with 275 °C determined as optimal.
• Analysis of twelve polymer standards (nylons, polyesters, olefins) using DART-AccuTOF™.
• Analysis of thirty-two forensic carpet samples (known and unknown compositions) using DART-AccuTOF™ and FTIR for confirmation.

Main Results:

• Successful identification and differentiation of all twelve polymer standards were achieved.
• All carpet samples with known compositions were correctly identified by class.
• Unknown carpet samples were accurately identified, with sub-class identification possible for nylon fibers.
• DART-AccuTOF™ results were confirmed by FTIR analysis.

Conclusions:

• DART-AccuTOF™ is a viable and effective analytical method for forensic carpet fiber identification.
• This technique can be integrated into standard forensic laboratory workflows to enhance fiber analysis capabilities.
• The method demonstrates potential for identifying specific polymer types and sub-classes, aiding in linking evidence to sources.