Enhancing Textile Fiber Identification with Detergent Fluorescence

Abstract

Discovering common origins of trace evidential textile fibers can be a challenging task when fiber structure or dye composition does not provide exclusive identifying information. Introduction of new chemical species after mass production and distribution of a textile may be exploited to trace its history and identify the origin of its fibers. In this article, fluorescence microscopy is used to examine the alteration in the fluorescence spectral fingerprint of single fibers resulting from exposure to commonly used detergents that contain fluorescent whitening agents. Dyed acrylic, cotton, and nylon fibers were laundered and the spectral contribution of the detergent on single fibers was quantified and shown to reach a maximum after five sequential washes; some detergents showed statistically meaningful differences to fiber spectra after only a single wash. Principal component cluster analysis was used to determine that the spectra of laundered fibers are distinct from the spectra of dyed, unwashed cotton or nylon, but not acrylic, fibers.

Nondestructive Total Excitation–Emission Fluorescence Microscopy Combined with Multi-Way Chemometric Analysis for Visually Indistinguishable Single Fiber Discrimination

“…The similarity of the investigated fibersnylon 361 fibers dyed with AY17 and AY23; acetate satin 105B fibers dyed with DB3 and DB14; polyester 777 fibers dyed with DR1 and DR 19; and acrylic 864 fibers dyed with BG1 and BG4is shown in Figures S1–S4. In addition to the contribution of the textile dye to the fluorescence spectrum of the fiber, our approach considers the contribution of fluorescence impuritiesi.e., impurities imbedded into the fibers during fabrication of garmentsas a reproducible source of fiber comparison. , Since the purity of all the reagent dyes is lower than 100%, the presence of unidentified fluorophores in the investigated fibers is possible.…”

“…Although fluorescence microscopy is currently used in forensic laboratories for single fiber examination, , measurements are made with the aid of band-pass filters that provide very limited information on the spectral profiles of fibers. Our approach takes fluorescence microscopy to a higher level of selectivity with the collection of excitation emission matrices (EEMs). , EEMswhich refer to a series of emission spectra recorded at various excitation wavelengthswere recorded with the aid of a microscope coupled to a spectrofluorimeter. The subtraction of EEMs from visually indistinguishable fibers provided the best excitation wavelength for recording two-dimensional fluorescence spectra (first order data).…”

“…The same approach was later applied to investigate laundering effects on textile fibers. The spectral fingerprints of brighteners and other detergent components adsorbed on the fibers improved fiber discrimination via RTF-EEMs-PCA …”

“…Our approach takes fluorescence microscopy to a higher level of selectivity with the collection of excitation emission matrices (EEMs). 32,33 EEMswhich refer to a series of emission spectra recorded at various excitation wavelengthswere recorded with the aid of a microscope coupled to a spectrofluorimeter. The subtraction of EEMs from visually indistinguishable fibers provided the best excitation wavelength for recording two-dimensional fluorescence spectra (first order data).…”

Excitation–emission matrix fluorescence spectroscopy combined with MCR-ALS as a tool for the forensic analysis of similar and dissimilar sets of textile fiber extracts

“…Recently, single ber identication with nondestructive excitation-emission uorescence spectroscopy combined with different chemometric techniques has been reported by our group. [9][10][11] This subject is of current interest, as is reported in a recent review on forensic comparison of synthetic bers. 12 Our approach takes room temperature uorescence (RTF) spectroscopy to a higher level of selectivity.…”