Editorial

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3 pages, 166 KiB

Open AccessEditorial

Advances in Fire Debris Analysis

by Michael E. Sigman and Mary R. Williams

Separations 2019, 6(1), 13; https://doi.org/10.3390/separations6010013 - 26 Feb 2019

Cited by 5 | Viewed by 3973

Abstract

The practice of forensic fire debris analysis and data interpretation in operational (i [...] Full article

(This article belongs to the Special Issue Advances in Fire Debris Analysis)

Research

Jump to: Editorial

18 pages, 3520 KiB

Open AccessArticle

Modern Instrumental Limits of Identification of Ignitable Liquids in Forensic Fire Debris Analysis

by Robin J. Abel, Grzegorz Zadora, P. Mark L. Sandercock and James J. Harynuk

Separations 2018, 5(4), 58; https://doi.org/10.3390/separations5040058 - 10 Dec 2018

Cited by 7 | Viewed by 5782

Abstract

Forensic fire debris analysis is an important part of fire investigation, and gas chromatography–mass spectrometry (GC-MS) is the accepted standard for detection of ignitable liquids in fire debris. While GC-MS is the dominant technique, comprehensive two-dimensional gas chromatography–mass spectrometry (GC×GC-MS) is gaining popularity. [...] Read more.

Forensic fire debris analysis is an important part of fire investigation, and gas chromatography–mass spectrometry (GC-MS) is the accepted standard for detection of ignitable liquids in fire debris. While GC-MS is the dominant technique, comprehensive two-dimensional gas chromatography–mass spectrometry (GC×GC-MS) is gaining popularity. Despite the broad use of these techniques, their sensitivities are poorly characterized for petroleum-based ignitable liquids. Accordingly, we explored the limit of identification (LOI) using the protocols currently applied in accredited forensic labs for two 75% evaporated gasolines and a 25% evaporated diesel as both neat samples and in the presence of interfering pyrolysate typical of fire debris. GC-MSD (mass selective detector (MS)), GC-TOF (time-of-flight (MS)), and GC×GC-TOF were evaluated under matched conditions to determine the volume of ignitable liquid required on-column for correct identification by three experienced forensic examiners performing chromatographic interpretation in accordance with ASTM E1618-14. GC-MSD provided LOIs of ~0.6 pL on-column for both neat gasolines, and ~12.5 pL on-column for neat diesel. In the presence of pyrolysate, the gasoline LOIs increased to ~6.2 pL on-column, while diesel could not be correctly identified at the concentrations tested. For the neat dilutions, GC-TOF generally provided 2× better sensitivity over GC-MSD, while GC×GC-TOF generally resulted in 10× better sensitivity over GC-MSD. In the presence of pyrolysate, GC-TOF was generally equivalent to GC-MSD, while GC×GC-TOF continued to show 10× greater sensitivity relative to GC-MSD. Our findings demonstrate the superior sensitivity of GC×GC-TOF and provide an important approach for interlaboratory benchmarking of modern instrumental performance in fire debris analysis. Full article

(This article belongs to the Special Issue Advances in Fire Debris Analysis)

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9 pages, 2809 KiB

Open AccessFeature PaperArticle

Application of Self-Organizing Maps to the Analysis of Ignitable Liquid and Substrate Pyrolysis Samples

by Nicholas Thurn, Mary R. Williams and Michael E. Sigman

Separations 2018, 5(4), 52; https://doi.org/10.3390/separations5040052 - 31 Oct 2018

Cited by 7 | Viewed by 3540

Abstract

Classification of un-weathered ignitable liquids is a problem that is currently addressed by visual pattern recognition under the guidelines of Standard Test Method for Ignitable Liquid Residues in Extracts from Fire Debris Samples by Gas Chromatography-Mass Spectrometry, ASTM E1618-14. This standard method does [...] Read more.

Classification of un-weathered ignitable liquids is a problem that is currently addressed by visual pattern recognition under the guidelines of Standard Test Method for Ignitable Liquid Residues in Extracts from Fire Debris Samples by Gas Chromatography-Mass Spectrometry, ASTM E1618-14. This standard method does not separately address the identification of substrate pyrolysis patterns. This report details the use of a Kohonen self-organizing map coupled with extracted ion spectra to organize ignitable liquids and substrate pyrolysis samples on a two-dimensional map with groupings that correspond to the ASTM-classifications and separate the substrate pyrolysis samples from the ignitable liquids. The component planes give important information regarding the ions from the extracted ion spectra that contribute to the different classes. Some additional insight is gained into grouping of substrate pyrolysis samples based on the nature of the unburned material as a wood or non-wood material. Further subclassification was not apparent from the self-organizing maps (SOM) results. Full article

(This article belongs to the Special Issue Advances in Fire Debris Analysis)

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19 pages, 3949 KiB

Open AccessFeature PaperArticle

Fixed- and Variable-Temperature Kinetic Models to Predict Evaporation of Petroleum Distillates for Fire Debris Applications

by John W. McIlroy, Ruth Waddell Smith and Victoria L. McGuffin

Separations 2018, 5(4), 47; https://doi.org/10.3390/separations5040047 - 25 Sep 2018

Cited by 10 | Viewed by 3633

Abstract

Forensic fire debris analysis focuses on the identification of a foreign ignitable liquid in debris collected from the scene of a suspected intentional fire. Chromatograms of the extracted debris are compared to a suitable reference collection containing chromatograms of unevaporated and evaporated ignitable [...] Read more.

Forensic fire debris analysis focuses on the identification of a foreign ignitable liquid in debris collected from the scene of a suspected intentional fire. Chromatograms of the extracted debris are compared to a suitable reference collection containing chromatograms of unevaporated and evaporated ignitable liquids. However, there is no standardized method for the evaporation of ignitable liquids and the process itself can be time consuming, which limits the number of chromatograms of evaporated liquids included in the reference collection. This work describes the development and application of a variable-temperature kinetic model to predict evaporation rate constants and mathematically predict chromatograms corresponding to evaporated ignitable liquids. First-order evaporation rate constants were calculated for 78 selected compounds in diesel, which were used to develop predictive models of evaporation rates. Fixed-temperature models were developed to predict the rate constants at five temperatures (5, 10, 20, 30, 35 °C), yielding a mean absolute percent error (MAPE) of 10.0%. The variable-temperature model was then created from these data by multiple linear regression, yielding a MAPE of 16.4%. The model was applied to generate a reference collection of predicted chromatograms of diesel and kerosene corresponding to a range of evaporation levels. Using the modeled reference collection, successful identification of the liquid and level of evaporation in a test set of chromatograms was demonstrated. Full article

(This article belongs to the Special Issue Advances in Fire Debris Analysis)

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13 pages, 3300 KiB

Open AccessCommunication

Developing a Method for the Collection and Analysis of Burnt Remains for the Detection and Identification of Ignitable Liquid Residues Using Body Bags, Dynamic Headspace Sampling, and TD-GC×GC-TOFMS

by Katie D. Nizio and Shari L. Forbes

Separations 2018, 5(3), 46; https://doi.org/10.3390/separations5030046 - 17 Sep 2018

Cited by 5 | Viewed by 4890

Abstract

In cases of suspected arson, a body may be intentionally burnt to cause loss of life, dispose of remains, or conceal identification. A primary focus of a fire investigation, particularly involving human remains, is to establish the cause of the fire; this often [...] Read more.

In cases of suspected arson, a body may be intentionally burnt to cause loss of life, dispose of remains, or conceal identification. A primary focus of a fire investigation, particularly involving human remains, is to establish the cause of the fire; this often includes the forensic analysis of fire debris for the detection of ignitable liquid residues (ILRs). Commercial containers for the collection of fire debris evidence include metal cans, glass jars, and polymer/nylon bags of limited size. This presents a complication in cases where the fire debris consists of an intact, or partially intact, human cadaver. This study proposed the use of a body bag as an alternative sampling container. A method was developed and tested for the collection and analysis of ILRs from burnt porcine remains contained within a body bag using dynamic headspace sampling (using an Easy-VOC™ hand-held manually operated grab-sampler and stainless steel sorbent tubes containing Tenax TA) followed by thermal desorption comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (TD-GC×GC-TOFMS). The results demonstrated that a body bag containing remains burnt with gasoline tested positive for the presence of gasoline, while blank body bag controls and a body bag containing remains burnt without gasoline tested negative. The proposed method permits the collection of headspace samples from burnt remains before the remains are removed from the crime scene, limiting the potential for contamination and the loss of volatiles during transit and storage. Full article

(This article belongs to the Special Issue Advances in Fire Debris Analysis)

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14 pages, 2301 KiB

Open AccessFeature PaperArticle

Model Distribution Effects on Likelihood Ratios in Fire Debris Analysis

by Alyssa Allen, Mary R. Williams, Nicholas A. Thurn and Michael E. Sigman

Separations 2018, 5(3), 44; https://doi.org/10.3390/separations5030044 - 03 Sep 2018

Cited by 6 | Viewed by 3913

Abstract

Computational models for determining the strength of fire debris evidence based on likelihood ratios (LR) were developed and validated against data sets derived from different distributions of ASTM E1618-14 designated ignitable liquid class and substrate pyrolysis contributions using in-silico generated data. The models [...] Read more.

Computational models for determining the strength of fire debris evidence based on likelihood ratios (LR) were developed and validated against data sets derived from different distributions of ASTM E1618-14 designated ignitable liquid class and substrate pyrolysis contributions using in-silico generated data. The models all perform well in cross validation against the distributions used to generate the model. However, a model generated based on data that does not contain representatives from all of the ASTM E1618-14 classes does not perform well in validation with data sets that contain representatives from the missing classes. A quadratic discriminant model based on a balanced data set (ignitable liquid versus substrate pyrolysis), with a uniform distribution of the ASTM E1618-14 classes, performed well (receiver operating characteristic area under the curve of 0.836) when tested against laboratory-developed casework-relevant samples of known ground truth. Full article

(This article belongs to the Special Issue Advances in Fire Debris Analysis)

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27 pages, 9170 KiB

Open AccessArticle

Detection and Characterization of Ignitable Liquid Residues in Forensic Fire Debris Samples by Comprehensive Two-Dimensional Gas Chromatography

by Andjoe A. S. Sampat, Brenda Van Daelen, Martin Lopatka, Hans Mol, Guido Van der Weg, Gabriel Vivó-Truyols, Marjan Sjerps, Peter J. Schoenmakers and Arian C. Van Asten

Separations 2018, 5(3), 43; https://doi.org/10.3390/separations5030043 - 27 Aug 2018

Cited by 15 | Viewed by 10080

Abstract

This study covers an extensive experimental design that was developed for creating simulated fire debris samples under controlled conditions for the detection and identification of ignitable liquids (IL) residues. This design included 19 different substrates, 45 substrate combinations with and without ignitable liquids, [...] Read more.

This study covers an extensive experimental design that was developed for creating simulated fire debris samples under controlled conditions for the detection and identification of ignitable liquids (IL) residues. This design included 19 different substrates, 45 substrate combinations with and without ignitable liquids, and 45 different ILs from three classes (i.e., white spirit, gasoline, and lamp oil). Chemical analysis was performed with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOFMS) for improved separation and compound identification. The enhanced peak capacity offered by GC×GC-TOFMS allowed the use of a target compound list in combination with a simple binary decision model to arrive at quite acceptable results with respect to IL detection (89% true positive and 7% false positive rate) and classification (100% correct white spirit, 79% correct gasoline, and 77% correct lamp oil assignment). Although these results were obtained in a limited set of laboratory controlled fire experiments including only three IL classes, this study confirms the conclusions of other studies that GC×GC-TOFMS can be a powerful tool in the challenging task of forensic fire debris analysis. Full article

(This article belongs to the Special Issue Advances in Fire Debris Analysis)

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9 pages, 1591 KiB

Open AccessArticle

Application of Headspace Gas Chromatography-Ion Mobility Spectrometry for the Determination of Ignitable Liquids from Fire Debris

by María José Aliaño-González, Marta Ferreiro-González, Gerardo F. Barbero, Miguel Palma and Carmelo G. Barroso

Separations 2018, 5(3), 41; https://doi.org/10.3390/separations5030041 - 13 Aug 2018

Cited by 19 | Viewed by 6451

Abstract

A fast and correct identification of ignitable liquid residues in fire debris investigation is of high importance in forensic research. Advanced fast analytical methods combined with chemometric tools are usually applied for these purposes. In the present study, the Headspace Gas Chromatography-Ion Mobility [...] Read more.

A fast and correct identification of ignitable liquid residues in fire debris investigation is of high importance in forensic research. Advanced fast analytical methods combined with chemometric tools are usually applied for these purposes. In the present study, the Headspace Gas Chromatography-Ion Mobility Spectrometry (HS-GC-IMS) combined with chemometrics is proposed as a promising technique for the identification of ignitable liquid residues in fire debris samples. Fire debris samples were created in the laboratory, according to the Destructive Distillation Method for Burning that is provided by the Bureau of Forensic Fire and Explosives. Four different substrates (pine wood, cork, paper, and cotton sheet) and four ignitable liquids of dissimilar composition (gasoline, diesel, ethanol, and paraffin) were used to create the fire debris. The Total Ion Current (TIC) Chromatogram combined with different chemometric tools (hierarchical cluster analysis and linear discriminant analysis) allowed for a full discrimination between samples that were burned with and without ignitable liquids. Additionally, a good identification (95% correct discrimination) for the specific ignitable liquid residues in the samples was achieved. Based on these results, the chromatographic data from HS-GC-IMS have been demonstrated to be very useful for the identification and discrimination of ignitable liquids residues. The main advantages of this approach vs. traditional methodology are that no sample manipulation or solvent is required; it is also faster, cheaper, and easy to use for routine analyses. Full article

(This article belongs to the Special Issue Advances in Fire Debris Analysis)

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