Near infrared spectral imaging for the analysis of dynamite residues on human handprints

• NIR-HSI and chemometrics for the detection of dynamite residues on handprints.
• PLS-DA analysis to detect and classify pixels contaminated with dynamite residues.
• Sensitivity and specificity of 100% for both calibration and cross validation.
• Results show the capability of NIR-HSI for fast identification of explosive residues.

This study examines the utility of near infrared hyperspectral imaging (NIR-HSI) combined with chemometrics for the detection of dynamite residues on human handprints. Polyvinyl sheets containing dynamite residues were then analysed with the NIR-HSI system. A spectral library was developed by using partial least squares-discriminant analysis model (PLS-DA) to detect and classify the pixels contaminated with the dynamite residues. Values of sensitivity and specificity of 100% were obtained for both calibration and cross validation of dynamite and ammonium nitrate. The results were tested in real human handprints. Seven volunteers deposited their handprints into polyvinyl transparent sheets after the manipulation of a common type of dynamite which was mainly composed by ammonium nitrate. These results highlight the extremely high potential and capability of NIR-HSI combined with chemometrics for the fast and easy identification of explosive residues and additionally, its potential competence to detect the explosive manipulation.

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