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A Survey of Extraction Solvents in the Forensic Analysis of Textile Dyes

NCJ Number
Forensic Science Internationa Volume: 268 Dated: November 2016 Pages: 139-144
Date Published
November 2016
6 pages
Since a survey of dye extraction publications reveals that pyridine water (4:3) is among the most commonly cited extraction solvents across a range of fiber and dye chemistries, the current study evaluated the efficacy of this solvent system for the extraction of dyes from 172 commercially prevalent North- American textile dyes.

The characterization and identification of dyes in fibers can be used to provide investigative leads and strengthen associations between known and questioned items of evidence. The isolation of a dye from its matrix (e.g., a textile fiber) permits detailed characterization, comparison, and, in some cases, identification, using methods such as thin layer chromatography in conjunction with infrared and Raman spectroscopy. In the current study, the evaluated population represented seven dye application classes and 18 chemical classes, spanning nine types of commercial textile fibers. Survey results indicate that approximately 82 percent of the dyestuffs examined were extractable, using this solvent system. The results presented summarize the extraction efficacy by class and fiber type. They show that this solvent system is applicable to a wider variety of classes and fibers than previously indicated in the literature. Although there is no universal solvent for fiber extraction, these results show that pyridine water is an excellent first step for extracting unknown dyes from questioned fibers in forensic casework. (Publisher abstract modified)

Date Published: November 1, 2016