Analysis of Single Synthetic Fibers Using a Portable Total Reflection X-ray Fluorescence Spectrometer.

In this study, single synthetic fibers obtained from several textile products were analyzed by a portable total reflection X-ray fluorescence spectrometer. Characteristic elements, which would originate from such materials as catalysts, delustering agents, and dyes used for manufacturing synthetic fibers, were detected from single synthetic fiber samples, and the difference in the types of characteristic elements among the single synthetic fiber samples was observed.

Nondestructive discrimination of red silk single fibers using total reflection X-ray fluorescence spectrometry and synchrotron radiation X-ray fluorescence spectrometry.

In a strangulation case, when a necktie is used as a murder weapon, the dyed silk single fiber becomes an important evidence sample to solve the crime. Dyed silk single fibers contain elements, such as Cr and Co, which are obtained from dyeing using metal mordants. Currently, there are no nondestructive and sufficiently sensitive elementary analytical methods for the forensic analysis of single fibers. Therefore, in this study, eight commercially available red silk samples were collected and used for total reflection X-ray fluorescence (TXRF) and synchrotron radiation X-ray fluorescence (SR-XRF) spectrometry. Benchtop TXRF detected both S in the silk protein and Cl and Ca, which are elements absorbed from the environment by silkworms, but also Cr, which is a dyeing derivative for metal mordants. The presence of Cr and Zn, in addition to the Zn/Cr signal intensity ratios, was reported to be particularly useful identifiers. In SR-XRF, the presence of Cr, Co, Zn, and Br and the Zn/Cr signal intensity ratios were reported to be useful discriminating indicators. In this study, the nondestructive discrimination capabilities of TXRF and SR-XRF measurements for the samples were found to be 85.7% and 100%, respectively. Therefore, we propose a combination of TXRF and SR-XRF as a new nondestructive single fiber identification method for forensic science. Moreover, if partial destruction of a single fiber is allowed, the observation of the cross section and micro-Fourier-transform infrared spectroscopy measurements is useful for identifying red silk fibers.

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-µXRF spectra showed similar patterns for the fiber samples that were analyzed.