“Click and Screen” Technology for the Detection of Explosives on Human Hands by a Portable MicroNIR–Chemometrics Platform

Portable near-infrared spectroscopy (MicroNIR) coupled with chemometrics was investigated for the first time as a new tool for the on-site analysis of explosives on human hands. A novel, entirely on-site approach based on the use of a particular miniaturized NIR spectrometer was developed and validated in cooperation with the Scientific Investigation Department (Carabinieri RIS) of Rome. Spectra from 25 volunteers were acquired in the NIR region in reflectance mode, and a prediction model was optimized on the basis of chemometric tools. The results demonstrated the capability of the MicroNIR-Chemometrics approach to correctly identify explosives from hands and not be affected by the complexity and variability of the matrix. This study has shown that the MicroNIR-Chemometrics approach can be considered a useful, fast, nondestructive tool identifying the manipulation of explosives in real forensic cases.