title: Bayesian Integration and Classification of Composition C-4 Plastic Explosives Based on Time-of-Flight-Secondary Ion Mass Spectrometry and Laser Ablation-Inductively Coupled Plasma Mass Spectrometry.
abstract: Time-of-flight-secondary ion mass spectrometry (TOF-SIMS) and laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) were used for characterization and identification of unique signatures from a series of 18 Composition C-4 plastic explosives. The samples were obtained from various commercial and military sources around the country. Positive and negative ion TOF-SIMS data were acquired directly from the C-4 residue on Si surfaces, where the positive ion mass spectra obtained were consistent with the major composition of organic additives, and the negative ion mass spectra were more consistent with explosive content in the C-4 samples. Each series of mass spectra was subjected to partial least squares-discriminant analysis (PLS-DA), a multivariate statistical analysis approach which serves to first find the areas of maximum variance within different classes of C-4 and subsequently to classify unknown samples based on correlations between the unknown data set and the original data set (often referred to as a training data set). This method was able to successfully classify test samples of C-4, though with a limited degree of certainty. The classification accuracy of the method was further improved by integrating the positive and negative ion data using a Bayesian approach. The TOF-SIMS data was combined with a second analytical method, LA-ICPMS, which was used to analyze elemental signatures in the C-4. The integrated data were able to classify test samples with a high degree of certainty. Results indicate that this Bayesian integrated approach constitutes a robust classification method that should be employable even in dirty samples collected in the field.
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99352, United States.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Mahoney
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99352, United States.
authors.forename: Ryan T
authors.initials: RT
authors.lastname: Kelly
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99352, United States.
authors.forename: Liz
authors.initials: L
authors.lastname: Alexander
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99352, United States.
authors.forename: Matt
authors.initials: M
authors.lastname: Newburn
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99352, United States.
authors.forename: Sydney
authors.initials: S
authors.lastname: Bader
authors.affiliation: National Security Directorate, Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99352, United States.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Ewing
authors.affiliation: National Security Directorate, Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99352, United States.
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Fahey
authors.affiliation: National Security Directorate, Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99352, United States.
authors.forename: David A
authors.initials: DA
authors.lastname: Atkinson
authors.affiliation: Johns Hopkins University , Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland 20723, United States.
authors.forename: Nathaniel
authors.initials: N
authors.lastname: Beagley
mesh_terms: D001499:Bayes Theorem; D016002:Discriminant Analysis; D053834:Explosive Agents / Q000032:analysis* / Q000737:chemistry* / Q000145:classification; D016018:Least-Squares Analysis; D013058:Mass Spectrometry; D018629:Spectrometry, Mass, Secondary Ion; D013997:Time Factors
chemical_list: D053834:Explosive Agents