Criminals with a penchant for dyeing their hair could soon pay for their vanity. Scientists have found a way to analyze hair samples at crime scenes to rapidly determine whether it was colored and what brand of dye was used. Their report appears in the American Chemical Society journal Analytical Chemistry.

Richard P. Van Duyne and Dmitry Kurouski note that analyzing hairs for forensic investigations, despite what TV shows would have you believe, can be a labor-intensive and flawed process. Testing samples for DNA requires an intact bulb or root, which isn't always present. Plus, the procedure is time-consuming, which can cause a large backlog of cases. So investigators will often opt to use the more traditional method of visually comparing hair from a crime scene with samples from suspects using a microscope. But this technique doesn't necessarily provide conclusive results. Van Duyne and Kurouski wanted to find a more practical and accurate way to analyze hair.

The researchers turned to surface-enhanced Raman spectroscopy (SERS) with a portable Raman spectrometer. SERS can detect minute amounts of illicit drugs, explosives, gunshot residue and body fluids. With this method, the team could rapidly confirm whether hair samples, even microscopic ones, were dyed and what brand of colorant was used. This highly sensitive technique could help forensic investigators analyze hair quickly in the field, the researchers say.