The Identification of Polyester Fibers Dyed with Disperse Dyes for Forensic Purposes

Abstract

In forensic laboratories, the most commonly analyzed microtraces are microscopic fragments of single fibers. One of the main goals of the examination of fragments of fibers a few millimeters long is to determine their characteristic physicochemical properties and compare them with fibers originating from a known source (e.g., a suspect’s clothes). The color and dyes of fiber microtraces play an important role in their research and evaluation, being analyzed by means of microscopic, spectroscopic, and chromatographic methods. The results of examinations conducted with the use of spectroscopic techniques might be ambiguous due to overlapping bands of absorption and the transmission and dispersion of electromagnetic radiation corresponding to the specific chemical structure of the fibers and their dyes. For this reason, it is very important to improve currently available spectroscopic methods and/or to propose new ones that allow evidential materials to be analyzed in a much more reliable way. In this review, the possibility of the use of chromatographic techniques with different detection systems for such analyses is underlined. This review covers the different analytical methods used in the forensic analysis of polyester fibers dyed with disperse dyes. Polyester fibers occupy the first position among synthetic fibers in their use for a variety of purposes, and disperse dyes are commonly applied for dyeing them.

Characterization of synthetic dyes for environmental and forensic assessments: A chromatography and mass spectrometry approach

“…MS allows for more specificity in differentiating dyes compared to LC alone, as response wavelength and retention time may be too similar to identify what compounds are present successfully. Furthermore, MS allows for the identification of substances at very low quantities, even when matrices are present and ionization suppression could affect the detection of all species [17,75–78].…”

“…In the case of disperse dyes, a common practice for analysis and identification is the use of LC or LC‐MS with the sample extracted from the fiber [17,77,79,100,101]; however, several studies have shown that dyes can be identified with direct ionization methods [7,74]. DART uses a stream of heated metastable gas to vaporize and ionize analytes, sending them directly into the mass spectrometer for analysis [7,85].…”

Raman spectrometry as a screening tool for solvent-extracted azo dyes from polyester-based textile fibres

“…Various analytical techniques have been used to characterise and/or identify functional groups and particularly the azo group [14] in dye molecules. In general, analytical approaches include an extraction stage using low polarity solvents, such as chlorobenzene, methanol, dimethylsulfooxide, acetonitrile and dimethylformamide [15,16].…”

“…Different solvent mixtures were assessed and the best results were obtained with a mixture of ethanol and diethyl ether, which has not previously been reported as an extraction medium for medium-polarity azo dyes on polyesters fibres. Other studies have used more polar/toxic and/or complex mixtures of extractants [14]. The potential advantages of the reported analytical approach include the simplicity and rapid procedure of the extraction stage, the use of less toxic solvents, and only minimal amounts of both sample and extractant.…”

Performance Evaluation of Fluorescence and Photostability of Coumarin Disperse Yellow 82

“…The classification of disperse dyes by chromogen is significant for forensic analysts. Azo and anthraquinone disperse dyes are the main classes of disperse dyes in the market with the highest possibility of being subjected to forensic investigations [8]. Coumarin dyes have also gained recognition as one of the greatest commercially significant groups of fluorescent dyes having yellow with a green fluorescence as most commercial products.…”