High‐Performance Liquid Chromatography–Ultraviolet–Visible Spectroscopy–Electrospray Ionization Mass Spectrometry Method for Acrylic and Polyester Forensic Fiber Dye Analysis^*

Abstract

A critical point of comparison between a fiber collected from a crime scene and a fiber from a known source is the color. Fiber dye analysis using thin-layer chromatography or ultraviolet (UV)-visible (Vis) microspectrophotometry provides useful, although limited, data for comparison. High-performance liquid chromatography-electrospray ionization mass spectrometry (LC/MS) overcomes these limitations by integrating chromatography, ultraviolet-visible spectroscopy, and mass spectrometry into a single instrument. In order to evaluate the applicability of the LC/MS to forensic fiber dye analysis, a multi-stage chromatographic method using acidified water and acidified acetonitrile was developed that separated and identified a mixture of 15 basic and 13 disperse dye standards. The LC/MS also detected and analyzed dyes extracted from individual 0.5 cm acrylic and polyester fibers, demonstrating its applicability to this type of analysis. With regard to the analysis of disperse dyes in polyester fibers, the replacement of pyridine with acetonitrile in the extraction system allowed direct injection of the extracts into the LC/MS. The advantage of the LC/MS over other instrumental methods of textile dye analysis is demonstrated by the analysis and differentiation of three black acrylic fibers: two fibers had similar UV-Vis spectra but were differentiated with chromatography and two had similar UV-Vis spectra and chromatograms but were differentiated using the mass spectrometer.

Extraction and Analysis of Disperse Dyes from Colored Polyester Single Fibers Using Liquid Chromatography/Linear Ion Trap Tandem Mass Spectrometry

“…Petrick et al analyzed dyes in single fibers (5 mm in length) using LC/MS, 30 while referring to previous reports that a single 2 -10-mm-long dyed fiber contains 2 -200 ng of dye, and that the LODs were 80 -1280 pg for 5 μL of the extracted disperse dyes injected into an HPLC (DAD) system. 24,26 As shown in Table 2, the LODs identified by DAD based on the peak heights for the nine disperse dyes were 500 -1750 pg for a 5-μL injection, but those determined from the SRM chromatograms were 1 -15 pg.…”

“…These extractions were performed so as to determine the most effective dye extraction solvent among an acetonitrile/water (4:3, v/v) mixture, a methanol/water (1:1, v/v) mixture, and DMF. The acetonitrile/water (4:3, v/v) mixture was recently recommended as an extraction solvent for LC/MS, 30 replacing the pyridine/ water (4:3, v/v) mixture, because they have approximately the same extraction ability for dyes. 30 For the extraction, 30 μL of the solvent was placed with a textile thread in a glass capillary tube [Microcaps, for 100 μL (length: 70 mm, i.d.…”

“…The acetonitrile/water (4:3, v/v) mixture was recently recommended as an extraction solvent for LC/MS, 30 replacing the pyridine/ water (4:3, v/v) mixture, because they have approximately the same extraction ability for dyes. 30 For the extraction, 30 μL of the solvent was placed with a textile thread in a glass capillary tube [Microcaps, for 100 μL (length: 70 mm, i.d. : 1 mm), Drummond Scientific Company, Pennsylvania, USA] and heated at 100 C for 30 min in a heat block.…”

“…1,2 Many studies have been conducted to analyze the dyes in colored fibers using microspectrophotometry, [3][4][5][6][7][8][9][10] TLC, [11][12][13][14][15][16][17][18][19] HPLC, [20][21][22][23][24][25] and LC/MS, [26][27][28][29][30] because these dyes can provide significant information in forensic analyses.…”

“…31 Dye-extractions are performed by heating colored fibers in various solvents and solvent mixtures, [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] including the recommended pyridine/water (4:3, v/v) mixture by the SWGMAT guidelines. 32 We reported a method for extracting a residual surfactant from threads using centrifugal filtration of a methanol solution extracted into a glass capillary.…”