Mass Spec Method Fingerprints Dyed Fibers

Forensic scientists hoping to cause minimal damage to critical evidence may have a new analytical technique to study suspicious fibers found at crime scenes (Anal. Chem., DOI: 10.1021/ac3025569). Chuanzhen Zhou, David Hinks, and coworkers at North Carolina State University developed a mass spectrometry method to identify dyes on nylon, and they are now working to extend the technique to polyester and cotton fibers. The researchers first clean the fiber surface by using a C₆₀⁺ fullerene ion beam and then use Bi⁺ ion beam time-of-flight secondary ion mass spectrometry to take a chemical fingerprint of the dye, fabric, and any other trace material on the fiber surface. Hinks says the technique could provide essential backup for existing forensic fiber analysis techniques while consuming an insignificant amount of the evidence to do the experiment. Most forensic labs currently use polarized light microscopy to identify fibers, and some labs then extract dye from the fiber and analyze it by thin-layer chromatography, he notes. By analyzing fiber and dye together in situ, the new technique will allow researchers to identify the material’s trace contaminants for additional comparison between fibers obtained from crime scenes and from suspects, the researchers suggest.