NCJ Number
231385
Journal
Canadian Society of Forensic Science Journal Volume: 43 Issue: 1 Dated: March 2010 Pages: 16-30
Date Published
March 2010
Length
15 pages
Annotation
This study evaluated various aspects of UV-VIS microspectrophotometry for routine color analysis of fibers in a forensic laboratory, and was compared to visible microspectrophotometry.
Abstract
Quartz plates and glycerine mounting medium do not absorb within the spectral range of 240 nm to 380 nm. However, glass and XAM mounting medium, which are routinely used for microscopic fiber analysis and visible microspectrophotometry, were found to absorb substantially below 320 nm. The spectral interference from the polymeric composition of fibers was also studied. Wool, silk, polyester and acrylics with methylvinylpyridine (MVP) are highly absorbing below 310 nm, so dye color analysis could not be applied in that region for these fiber types. Acetates, nylons, modacrylics and acrylics with poly - vinylpyrrolidone (PVP) have low or moderate absorbance below 310 nm, which causes some interference. Cotton, rayon, and olefins do not absorb in the UV range. Analysis of glass-mounted fibers in the UV-VIS range can provide increased discrimination over analysis in the visible range. A flowchart decision tree was developed to guide the analyst in the application of UV-VIS microspectrophotometry for fiber analysis. Dyed fibers could initially be analysed under glass mount by UV-VIS microspectrophotometry from 320 nm to 770 nm. For fiber types with little or no polymeric UV spectral interference, additional spectral information could be obtained from UV-VIS analysis on quartz slides, measured from 240 nm to 770 nm. Tables, figures, and references (Published Abstract)