Using Surface-Enhanced Raman Spectroscopy (SERS) for the Detection of Underlaying Dyes on Re-Dyed Hair

Abstract

Hair evidence is one of the most common types of evidence in the field of forensic sciences, yet analysis is subjective and is interpreted by an analyst, adding in bias to the outcome of the analysis. By applying Surface Enhanced Raman Spectroscopy (SERS) to the analysis of dyed hairs, forensic hair analysis can become more than just a subjective comparison between two samples and can help include or exclude individuals from being present at the scene of a crime. This alone shows the importance and need for more advanced and objective forms of hair analysis methodology in the field of forensic sciences. In order to remove the subjectivity from forensic hair analysis, the application of surface-enhanced Raman spectroscopy (SERS) is effective and nondestructive. Through this technique, we have shown that SERS can be utilized to identify hair dyes on a single strand of hair, detect underlying dyes that are present when a sample of hair has been dyed multiple times, and determine that a dye can be detected on hair that was dyed up to 9 weeks prior to analysis.