The Discrimination of Blue Cotton Fibers by High Pressure Liquid Chromatography/Mass Spectrometry

Since fiber is commonly found at crime scenes and can associate the physical contact between the suspect and victim, dyes have played an important role in the identification and comparison of fibers. Current fiber analysis is sufficient in characterization of dye classes used on cotton fibers, but it has not utilized the potential of High-Performance Liquid Chromatography Mass Spectrometer (HPLC/MS) to assess the matching of cotton fibers in a casework situation. Cotton fibers from blue denims cannot be discriminated using current fiber analysis methods and are regarded as having little evidential value. Therefore, this study is designed to evaluate the application of HPLC-MS method to discriminate blue cotton fibers.;The dyes from blue denim fibers were first classified to be vat dyes. Then a solvent extraction system was developed to be compatible with the HPLC/MS system. Successful extraction of dyes from cotton was achieved with a mixture of acidified acetonitrile (pH 2.5): acidified water (pH 2.5) (4:3) at 120°C for 30 minutes through visual comparisons. After the extraction procedures were developed, the HPLC/MS method for dye extraction analysis was optimized. The method was then evaluated through the analysis of the single and yarn samples. The results showed that the established HPLC/MS method could not discriminate the single fibers, but it could discriminate the yarn samples. The UV/Vis data alone could not discriminate the yarn samples apart from one another, but the combination of UV/Vis data, chromatograms, and mass spectra, the yarn samples were discriminated one sample from one another. In conclusion, HPLC/MS is a viable method for discriminating blue cotton samples.