Hair samples found at crime scenes can impact forensic investigations, but current sample analysis methods—DNA testing and microscopy comparisons—are time-intensive and often produce inconclusive results, respectively. Recognizing this, two Northwestern University (Evanston, IL) researchers tested a Raman spectroscopy method to see if it could determine whether the samples were treated with hair dye and, if so, the brand of dye used. Their reasoning was that such information could help compare hair samples with the hair of suspects. The method they used can identify chemicals with single-molecule resolution and requires minimal sample.1
Richard P. Van Duyne, the Charles E. and Emma H. Morrison Professor of Chemistry at Northwestern, and Dmitry Kurouski, a postdoctoral fellow in Van Duyne's lab, used surface-enhanced Raman spectroscopy (SERS) to identify the chemicals in hair dyes within minutes. The two researchers first used a confocal Raman spectrometer to acquire SERS spectra from a variety of different hair dyes, followed by a portable Raman spectrometer to prove that the method can be used in the field. Results confirmed that all vibrational bands visible in SERS spectra acquired with the confocal Raman spectrometer were also present when they used the portable Raman spectrometer.
1. D. Kurouski and R. P. Van Duyne, Anal. Chem., http://dx.doi.org/10.1021/ac504405u (2015).