Association of Ignitable Liquid Residues to Neat Ignitable Liquids in the Presence of Matrix Interferences Using Chemometric Procedures*,†

Abstract: In fire debris analysis, weathering of ignitable liquids and matrix interferences can make the identification of ignitable liquid residues (ILRs) difficult. An objective method was developed to associate ILRs with the corresponding neat liquid with discrimination from matrix interferences using principal components analysis (PCA) and Pearson product moment correlation (PPMC) coefficients. Six ignitable liquids (gasoline, diesel, ultra pure paraffin lamp oil, adhesive remover, torch fuel, paint thinner) were spiked onto carpet, which was burned, then extracted using passive headspace extraction, and analyzed by gas chromatography‐mass spectrometry. Both light and heavy burn conditions were investigated. In the PCA scores plot, ignitable liquids were discriminated based on alkane and aromatic content. All ILRs were successfully associated with the corresponding neat liquid using both PCA and PPMC coefficients, regardless of the extent of burning. The method developed in this research may make the association of ILRs with corresponding neat liquids more objective.     

The Longitudinal Relationships Between Rural Adolescents’ Prosocial Behaviors and Young Adult Substance Use

While many adolescents and young adults experiment with substances (e.g., alcohol, cigarette smoking, marijuana), recent research suggests that rural youth and young adults may be more at risk for substance use than their urban counterparts. This study was designed to examine the longitudinal relationships between rural adolescents’ prosocial behaviors and substance use in young adulthood. Furthermore, we examined the potential mediating effects of adolescent substance use, academic investment, and delinquency. Rural youth (N = 531; 263 girls) were surveyed in grades 10–12 (Time 1; M age = 16.17; SD = .91) and again in early adulthood (Time 2). Measures of prosocial behaviors, substance use, academic investment, and deviant activities were assessed at Time 1. At Time 2, measures of marijuana use, cigarette smoking, and getting drunk were administered. Overall, the findings showed that rural adolescents who frequently exhibit prosocial behaviors are less likely to engage in substance use in young adulthood than those who exhibit relatively low levels of prosocial behaviors. These findings indicate that prosocial behaviors may have positive health consequences, establishing behavioral trajectories that lead to lower levels of risky health behaviors in adulthood in rural populations.