An Evaluation of Total Reflection X-Ray Fluorescence as a Tool for Forensic Discrimination of Single Polyester Fibers

Total reflection X-ray fluorescence (TXRF) spectrometry was applied to a forensic discrimination of single polyester fibers. In a non-destructive direct measurement of 5 mm long single fibers used for forensic references, trace metallic elements such as Ti, Sb, Ge, Mn, and Co, found in additives and catalyst residues, were detected using a benchtop TXRF spectrometer. The individual elemental compositions of the fibers were identified, and correlations between the compositions and manufacturers were established using principal component analysis (PCA). Black polyester fibers sampled from the car trunk mats were also analyzed. Several fibers were found to contain both Sb and Ge, elements that characterize different polymerization catalysts; this indicates that the fibers were composed of recycled materials. The TXRF and SR-mu XRF spectra showed similar patterns for the fiber samples that were analyzed.

Automated summary

TXRF spectrometry was used to discriminate single polyester fibers in forensic applications, identifying trace metallic elements and establishing correlations between compositions and manufacturers using PCA. Analysis of black polyester fibers from car trunk mats revealed some fibers containing elements characteristic of different polymerization catalysts, suggesting they were made from recycled materials. The spectra obtained from TXRF and SR-mu XRF showed similar patterns for the analyzed fiber samples.