The Analysis of Colored Acrylic, Cotton, and Wool Textile Fibers Using Micro‐Raman Spectroscopy. Part 2: Comparison with the Traditional Methods of Fiber Examination

Abstract

In the second part of this survey, the ability of micro-Raman spectroscopy to discriminate 180 fiber samples of blue, black, and red cottons, wools, and acrylics was compared to that gathered with the traditional methods for the examination of textile fibers in a forensic context (including light microscopy methods, UV-vis microspectrophotometry and thin-layer chromatography). This study shows that the Raman technique plays a complementary and useful role to obtain further discriminations after the application of light microscopy methods and UV-vis microspectrophotometry and assure the nondestructive nature of the analytical sequence. These additional discriminations were observed despite the lower discriminating powers of Raman data considered individually, compared to those of light microscopy and UV-vis MSP. This study also confirms that an instrument equipped with several laser lines is necessary for an efficient use as applied to the examination of textile fibers in a forensic setting.

What can Raman spectroscopy do for criminalistics?

“…They demonstrated that the ability to obtain viable spectra significantly depended upon the laser wavelength used for analysis as well as the color and type of fiber . The second portion of this two‐part survey compared the results of analyzing 180 black, blue, and red cotton, wool, and acrylic fibers using Raman microspectroscopy with traditional methods including light microscopy, TLC, and UV–vis MSP . Raman spectroscopy is typically used to analyze the dyes in fibers and it was shown that by using four different wavelengths (i.e.…”

“…[92] The second portion of this two-part survey compared the results of analyzing 180 black, blue, and red cotton, wool, and acrylic fibers using Raman microspectroscopy with traditional methods including light microscopy, TLC, and UV-vis MSP. [93] Raman spectroscopy is typically used to analyze the dyes in fibers and it was shown that by using four different wavelengths (i.e. 514.5, 632.8, 785, and 830 nm), components in dye mixtures could be elucidated; where in some cases this was not achievable by other methods.…”

Blood identification and discrimination between human and nonhuman blood using portable Raman spectroscopy

“…This technique is a nondestructive analysis, it needs no sample preparation, and the sample size can be in the order of picograms. Recently, Raman spectroscopy has been shown to be an effective multipurpose analytical method for forensic applications: identification of drugs [3], lipsticks [4], fibers [5], paints [6], and ink [7]. A previous study reported the identification of body fluids using Raman spectroscopy [8].…”

Photofading in cotton fibers dyed using red, yellow, and blue direct dyes during examination with microspectrophotometry (MSP)

“…This allows color analysis to be performed directly on a sample mounted for microscopic examination without needing to remove the dye for a solution-based measurement [8]. MSP has been shown to have a high discriminatory power for differentiating between colored fibers, especially when the UV range is included in the analysis [4], [6]–[9], [12]. …”