Eastern Kentucky University

Poster Title

Trace-Fiber Color Discrimination by HPLC-DAD Using Both Ion-Suppression and Ion-Pairing Reagents

Institution

Eastern Kentucky University

Abstract

Analytical separation techniques play an important role in forensic science. Fiber evidence can be analyzed in many ways including microspectrophotometry, thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). TLC is a destructive method which is easy to carry out but lacks information about the ratios of the different dyes that are present. HPLC has been employed to a limited extent in forensic labs for dye analysis. While also destructive, it has been used successfully to separate and quantitate acid, disperse and basic textile dyes. To assist the Kentucky State Police Crime Lab in Frankfort, Kentucky, we have developed a method for separating dyes using HPLC with Diode Array Detection. Extraction of the dyes from nylon fabric was accomplished using a pyridine/water mixture at 150oC. The pyridine was removed under pressure and the extract was re-dissolved in 50% methanol/water. A TLC separation of this extract showed three distinct bands of red, yellow, and blue. HPLC separation using isocratic methanol/water mobile phase exhibited significant peak tailing and poor resolution. Improvement in the separation was found with a 1% acetic acid methanol/water mobile phase suggesting suppression of an ionic form of the dyes. The best separation was obtained upon addition of 5mM dodecane sulfonate to the 1% acetic acid/methanol/water mobile phase using gradient elution. Future work will focus on reducing the sample size needed to increase the forensic value of this type of analysis.

This document is currently not available here.

Share

COinS
 

Trace-Fiber Color Discrimination by HPLC-DAD Using Both Ion-Suppression and Ion-Pairing Reagents

Analytical separation techniques play an important role in forensic science. Fiber evidence can be analyzed in many ways including microspectrophotometry, thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). TLC is a destructive method which is easy to carry out but lacks information about the ratios of the different dyes that are present. HPLC has been employed to a limited extent in forensic labs for dye analysis. While also destructive, it has been used successfully to separate and quantitate acid, disperse and basic textile dyes. To assist the Kentucky State Police Crime Lab in Frankfort, Kentucky, we have developed a method for separating dyes using HPLC with Diode Array Detection. Extraction of the dyes from nylon fabric was accomplished using a pyridine/water mixture at 150oC. The pyridine was removed under pressure and the extract was re-dissolved in 50% methanol/water. A TLC separation of this extract showed three distinct bands of red, yellow, and blue. HPLC separation using isocratic methanol/water mobile phase exhibited significant peak tailing and poor resolution. Improvement in the separation was found with a 1% acetic acid methanol/water mobile phase suggesting suppression of an ionic form of the dyes. The best separation was obtained upon addition of 5mM dodecane sulfonate to the 1% acetic acid/methanol/water mobile phase using gradient elution. Future work will focus on reducing the sample size needed to increase the forensic value of this type of analysis.