The Identification of Cotton Fibers Dyed with Reactive Dyes for Forensic Purposes.

Daria Śmigiel-Kamińska,Jolanta Kumirska,Piotr Stepnowski,Jolanta Wąs-Gubała

doi:10.3390/molecules25225435

Daria Śmigiel-Kamińska, Jolanta Kumirska + Show 2 more

Open Access

https://doi.org/10.3390/molecules25225435

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Abstract

Some of the most common microtraces that are currently collected at crime scenes are fragments of single fibers. The perpetrator leaves them at a crime scene or takes them away, for example, on their clothing or body. In turn, the microscopic dimensions of such traces mean that the perpetrator does not notice them and therefore usually does not take action to remove them. Cotton and polyester fibers dyed by reactive and dispersion dyes, respectively, are very popular within clothing products, and they are hidden among microtraces at the scene of a crime. In our recently published review paper, we summarized the possibilities for the identification of disperse dyes of polyester fibers for forensic purposes. In this review, we are concerned with cotton fibers dyed with reactive dyes. Cotton fibers are natural ones that cannot easily be distinguished on the basis of morphological features. Consequently, their color and consequently the dye composition are often their only characteristics. The presented methods for the identification of reactive dyes could be very interesting not only for forensic laboratories, but also for scientists working in food, cosmetics or pharmaceutical/medical sciences.

Highlights

The experts from forensic laboratories are able to establish relationships between people, objects and a crime scene on the basis of the study of microtraces, very often in the form of fragments of single fibers, which sometimes help to reconstruct the circumstances of an event
In our recently published review paper [6], we summarized the possibilities for the identification of polyester fibers dyed with disperse dyes for forensic purposes
This stems from the lack of sensitivity of infrared absorbance to components that represent less than approximately 5% of a sample and the characteristically low level of dye concentration in most textile fibers, which is those dyed by reactive dyes

Summary

Introduction

The experts from forensic laboratories are able to establish relationships between people, objects and a crime scene on the basis of the study of microtraces, very often in the form of fragments of single fibers, which sometimes help to reconstruct the circumstances of an event. The RYB color format or color space builds the colors from a combination of red, yellow, and blue Each of these color values defines the intensity of the color as an integer value from 0 to 255. In the forensic laboratory, color is established firstly with the use of optical microscopy techniques, and on this basis, the evidential fibers are qualified for further research using more advanced analytical methods It has mainly concerned UV-Vis microspectrophotometry [1], Raman spectroscopy [2], and more traditional and low-cost chromatographic methods, such as thin-layer chromatography (TLC) [3]. Apart from the specificity of reactive dyes used for dyeing cotton in the textile industry, we intend to discuss the possibilities of using specific research methods in the analysis of this type of materials, i.e., chromatographic and spectroscopic ones

Reactive Dyes in the Textile Industry—An Overview

Reactive

VS dyes—these

D SO2CH2CH2OSO3Na

Cleavage of Reactive Dyes from Dyed Cotton Textiles

Extraction of Reactive Dyes from Dyed Cotton Fibers

Method

Extraction of Unknown Reactive Dyes from Dyed Cotton and Viscose

Chromatographic Conditions

Findings

Conclusions