The identification of Isopar H in vinyl flooring

Vinyl flooring manufacturers use plasticizers to decrease the viscosity and increase the pliability of vinyl. Several ignitable liquid plasticizers used in the manufacture of vinyl flooring were identified and investigated in this study. Twenty-nine collections from five major vinyl manufacturers, a total of 72 samples, were analyzed using passive headspace concentration in accordance with the American Society for Testing and Materials (ASTM E 1412-00) and gas chromatographic-mass spectrometric (GC-MS) analysis as described in ASTM E 1618-01 (1,2). Norpar products and TXIB (2,2,4-trimethyl-1,3-pentanediol diisobutyrate) are ignitable liquids common to the manufacture of vinyl flooring and were identified in all recently obtained samples. Isopar H is an ignitable liquid found in various products such as charcoal starters, copier toners, and some solvents (2). Of the 29 collections analyzed, Isopar H was only identified in Armstrong's Interflex-Traditions pattern.     

Hierarchical Cluster Analysis of Ignitable Liquids Based on the Total Ion Spectrum

Gas chromatography–mass spectrometry (GC–MS) data of ignitable liquids in the Ignitable Liquids Reference Collection (ILRC) database were processed to obtain 445 total ion spectra (TIS), that is, average mass spectra across the chromatographic profile. Hierarchical cluster analysis, an unsupervised learning technique, was applied to find features useful for classification of ignitable liquids. A combination of the correlation distance and average linkage was utilized for grouping ignitable liquids with similar chemical composition. This study evaluated whether hierarchical cluster analysis of the TIS would cluster together ignitable liquids of the same ASTM class assignment, as designated in the ILRC database. The ignitable liquids clustered based on their chemical composition, and the ignitable liquids within each cluster were predominantly from one ASTM E1618‐11 class. These results reinforce use of the TIS as a tool to aid in forensic fire debris analysis.     

Aromatic content in medium range distillate products--Part I: an examination of various liquids

Classification of ignitable liquids in accordance with voluntary consensus-based standards published by ASTM International has become increasingly specific, relying upon both the chemical composition and the boiling point range of submitted ignitable liquids. This classification system includes among others, specific classes for distillates and dearomatized distillates. In this study, a variety of medium-range ignitable liquids were analyzed by gas chromatography-mass spectrometry. Several methods of data analysis were utilized to examine the relative aliphatic and aromatic contents in these liquids. Results show that commercially available products in the medium range exhibit a broad range of compositions with respect to the relative proportion of aliphatic and aromatic compounds and that some liquids may not be easily classified. This study demonstrates the importance of examining the proportion of aliphatics:aromatics for classifying such liquids and suggests guidelines for differentiating medium range distillates, dearomatized distillates, and blended products.     

Progress Toward the Determination of Correct Classification Rates in Fire Debris Analysis,,

Principal components analysis (PCA), linear discriminant analysis (LDA), and quadratic discriminant analysis (QDA) were used to develop a multistep classification procedure for determining the presence of ignitable liquid residue in fire debris and assigning any ignitable liquid residue present into the classes defined under the American Society for Testing and Materials (ASTM) E 1618‐10 standard method. A multistep classification procedure was tested by cross‐validation based on model data sets comprised of the time‐averaged mass spectra (also referred to as total ion spectra) of commercial ignitable liquids and pyrolysis products from common building materials and household furnishings (referred to simply as substrates). Fire debris samples from laboratory‐scale and field test burns were also used to test the model. The optimal model's true‐positive rate was 81.3% for cross‐validation samples and 70.9% for fire debris samples. The false‐positive rate was 9.9% for cross‐validation samples and 8.9% for fire debris samples.     

Combined target factor analysis and Bayesian soft-classification of interference-contaminated samples: Forensic Fire Debris Analysis

A Bayesian soft classification method combined with target factor analysis (TFA) is described and tested for the analysis of fire debris data. The method relies on analysis of the average mass spectrum across the chromatographic profile (i.e., the total ion spectrum, TIS) from multiple samples taken from a single fire scene. A library of TIS from reference ignitable liquids with assigned ASTM classification is used as the target factors in TFA. The class-conditional distributions of correlations between the target and predicted factors for each ASTM class are represented by kernel functions and analyzed by Bayesian decision theory. The soft classification approach assists in assessing the probability that ignitable liquid residue from a specific ASTM E1618 class, is present in a set of samples from a single fire scene, even in the presence of unspecified background contributions from pyrolysis products. The method is demonstrated with sample data sets and then tested on laboratory-scale burn data and large-scale field test burns. The overall performance achieved in laboratory and field test of the method is approximately 80% correct classification of fire debris samples.     

ASTM standards for fire debris analysis: a review

The American Society for Testing and Materials (ASTM) recently updated its standards E 1387 and E 1618 for the analysis of fire debris. The changes in the classification of ignitable liquids are presented in this review. Furthermore, a new standard on extraction of fire debris with solid phase microextraction (SPME) was released. Advantages and drawbacks of this technique are presented and discussed. Also, the standard on cleanup by acid stripping has not been reapproved.Fire debris analysts that use the standards should be aware of these changes.     

Application of mist to fingermark detection: Misting with high-boiling-point liquid containing p-dimethylaminocinnamaldehyde and cyanoacrylate

In order to detect latent fingerprints that could be damaged by liquid or powder reagents, non-destructive processes such as gaseous reagents have been developed. In this report, we propose the use of fine mist generated when hot vapor of high-boiling-point liquids is rapidly cooled by surrounding air for fingermark detection. Octyl acetate (OA), 2-phenoxyethanol (2PE), and methyl decanoate (MD) were found to efficiently produce mist when heated to 230°C. By combining these liquids with p-dimethylaminocinnamaldehyde (DMAC) and cyanoacrylate (CN), our team demonstrated effective fluorescence staining of cyano-treated fingermarks using DMAC/OA misting or DMAC/2PE misting, and one-step fluorescence detection of latent fingermarks without cyanoacrylate treatment using DMAC/OA/CN misting or DMAC/MD/CN misting. Fingermark fluorescence was efficiently observed by excitation with a blue LED light (max. wavelength 470 nm) equipped with an interference filter and passing through a 520 nm long-pass filter. We successfully obtained fluorescent images from fingermarks on several substrate materials using the developed misting method.     

Persistence of floor coating solvents.

Using passive headspace concentration as described in ASTM E 1412 and gas chromatographic/mass spectrometric (GC/MS) analysis as described in ASTM E 1618, the author has studied the persistence of solvents in floor coating materials. Both oak and pine flooring boards were tested using stain, stain with polyurethane varnish, and oil finish after a period of ten months and 24 months. The solvents from all three floor-coating substances were easily detectable after 24 months, and showed no signs of diminution when compared with the samples tested earlier. These results point out the need for the submission of comparison samples whenever wood flooring samples are submitted for fire debris analysis in suspected arson cases.     

Chemical fingerprinting of petrochemicals for arson investigations using two-dimensional gas chromatography - flame ionisation detection and multivariate analysis

Two-dimensional gas chromatography is a mature, yet underutilised, separation technique able to provide the high resolution and peak capacity required for the study of complex samples such as oils. This paper presents the development of a comprehensive two-dimensional gas chromatography method with flame ionisation detection to profile easily available ignitable liquids commonly found in arson cases. The use of 2D chromatograms to profile different potential ignitable liquids was also explored for classification purposes. The chemical fingerprints produced were visually different and allowed the distinction of all the petroleum products tested. How the chemical fingerprints of each fuel changed over time was also assessed. Each sample was subjected to weathering with aliquots (1 mL) being collected every half hour for a five-hour period. Principal component analysis of the resulting data was able to demonstrate the effect of weathering for all fuels tested and established that it was still possible to differentiate between the various petrochemicals even after weathering. The work demonstrates an optimised analytical method for petrochemical product analysis that provides forensic scientists with a robust, fast and sensitive technique that can be used to determine not only which ignitable liquid was used in a fire (even after the fact) but also provide information on the specific fuel used.     

Quantitation of Synthetic Cannabinoids in Plant Materials Using High Performance Liquid Chromatography with UV Detection (Validated Method)

Plant based products laced with synthetic cannabinoids have become popular substances of abuse over the last decade. Quantitative analysis for synthetic cannabinoid content in the laced materials is necessary for health hazard assessments addressing overall exposure and toxicity when the products are smoked. A validated, broadly applicable HPLC‐UV method for the determination of synthetic cannabinoids in plant materials is presented, using acetonitrile extraction and separation on a commercial phenylhexyl stationary phase. UV detection provides excellent sensitivity with limits of quantitation (LOQs) less than 10 μg/g for many cannabinoids. The method was validated for several structural classes (dibenzopyrans, cyclohexylphenols, naphthoylindoles, benzoylindoles, phenylacetylindoles, tetramethylcyclopropylindoles) based on spike recovery experiments in multiple plant materials over a wide cannabinoid contents range (0.1–81 mg/g). Average recovery across 32 cannabinoids was 94% for marshmallow leaf, 95% for damiana leaf, and 92% for mullein leaf. The method was applied to a series of case‐related products with determined amounts ranging from 0.2 to >100 mg/g.     

Acid alteration of several ignitable liquids of potential use in arsons

Ignitable liquids such as fuels, alcohols and thinners can be used in criminal activities, for instance arsons. Forensic experts require to know their chemical compositions, as well as to understand how different modification effects could impact them, in order to detect, classify and identify them properly in fire debris. The acid alteration/acidification of ignitable liquids is a modification effect that sharply alters the chemical composition, for example, of gasoline and diesel fuel, interfering in the forensic analysis and result interpretation. However, to date there is little information about the consequences of this effect over other accelerants of interests. In this research paper, the alteration by sulfuric acid of several commercial thinners and other accelerants of potential use in arsons is studied in-depth. For that purpose, spectral (by ATR-FTIR) and chromatographic (by GC–MS) data were obtained from neat and acidified samples. Then, the spectral and chromatographic modifications of each studied ignitable liquid were discussed, proposing several chemical mechanisms that explain the new by-products produced and the gradual disappearance of the initial compounds. Hydrolysis, Fischer esterification and alkylation reactions are involved in the modification of esters, alcohols, ketones and aromatic compounds of the studied ignitable liquids. This information could be crucial for correctly identifying these accelerants. Additionally, an exploratory analysis revealed that some of the most altered ignitable liquid samples might be very similar with each other, which could have impact on casework.     

Unusual sources of Sn in GSR. An experimental study by SEM and IBA

Gunshot Residue (GSR) produced by the discharge of a firearm often provides very useful information in criminal investigations in cases involving the use of firearms. Scanning Electron Microscopy equipped with an Energy Dispersive X-ray Spectrometer (SEM-EDS) is typically used worldwide to visualize micrometric particles constituting GSR and to analyse their elemental composition. The 2017 ASTM Standard guide for gunshot residue analysis by scanning electron microscopy/energy dispersive X-ray spectroscopy specifies that “Particles classified as characteristic of GSR will have one of the following elemental compositions: Lead, antimony, barium; Lead, barium, calcium, silicon, tin”. For the first time, the presence of an additional element, such as Sn, plays a key role in ASTM particle classification. It is known that some ammunitions, used for pistols, revolvers and rifles, contain tin foil discs for sealing the primer mixture into the cup, resulting in GSR particles containing Sn. The authors faced some cases in which Sn was unexpectedly found in GSR particles from a 0.22 Long Rifle derringer and from some 12 gauge shotguns. No tin foil discs are used in rimfire ammunitions and there is no published evidence of tin foil discs in shotshell ammunitions. Following a “case by case” approach, experimental research has been carried out to explain how Sn can be present in GSR particles when the last discharged cartridge also does not contain any Sn either in components and in the explosive charges.Moreover, the use of Particle Induced X-ray Emission (PIXE) showed the capability to overcome overlap ambiguity of Sb and Sn peaks in the X-ray spectra, being a possible key issue in real shooting cases if Sn quantities are below the lower limit of SEM detection, especially when Sb is also present.     

Evaluation of a Headspace Solid‐Phase Microextraction Method for the Analysis of Ignitable Liquids in Fire Debris

The chemical analysis of fire debris represents a crucial part in fire investigations to determine the cause of a fire. A headspace solid‐phase microextraction (HS‐SPME) procedure for the detection of ignitable liquids in fire debris using a fiber coated with a mixture of three different sorbent materials (Divinylbenzene/Carboxen/Polydimethylsiloxane, DVB/CAR/PDMS) is described. Gasoline and diesel fuel were spiked upon a preburnt matrix (wood charcoal), extracted and concentrated with HS‐SPME and then analyzed with gas chromatography/mass spectrometry (GC/MS). The experimental conditions—extraction temperature, incubation and exposure time—were optimized. To assess the applicability of the method, fire debris samples were prepared in the smoke density chamber (SDC) and a controlled‐atmosphere cone calorimeter. The developed methods were successfully applied to burnt particleboard and carpet samples. The results demonstrate that the procedure that has been developed here is suitable for detecting these ignitable liquids in highly burnt debris.     

Criminalistic identification of PGM-containing products of mining and metallurgical companies

In early 1990 s some organized criminal groups started to develop a new field of illegal business, which involved thefts of intermediary products from mining and metal-producing plants in Russia and in the south of Africa. Since local sulfide copper/nickel ores contain certain concentrations of precious and platinum group metals (PGMs), the intermediary products recovered at different stages of metallurgical transformation of these ores are materials of high commercial value. Illicit transportation and refining of these materials in Western Europe and North America has evolved into a large-scale business, where a lot of unlawful revenues are being laundered. The most important tasks in combating this organized crime are as follows: to establish the facts when some PGM-containing semi-products had been received at certain refineries; to carry out the identification of these semi-products; and to prove that these semi-products had been produced by a certain company. As a rule, it is not difficult to establish the identity of a "clean product". However, when a material is a mix of several semi-products or a mix of some semi-product with masking substances, the identification of individual components becomes an extremely complicated task. The purpose of developing the "complex procedure for establishing the nature and source of origin of precious metal-bearing products of mining and metallurgical operations" was to make possible the identification of complex mixes comprised of various metallurgical semi-products. In the complex procedure that we have developed to characterize dispersed materials, distribution of particles by their elemental composition (the so-called "pseudophase" composition) was used instead of mineralogical composition. To determine the "pseudophase" composition by the method of scanning electron microscopy with X-ray spectral microanalysis (SEM-EDX), a representative sample of material containing not less than 1000 particles was analyzed. All microparticles can be divided into several types. Each type is characterized by an association of chemical elements contained. The first stage includes the study of elemental composition by inductively coupled plasma optical emission spectrometry and inductively coupled plasma mass-spectrometry; and the study of phase composition by X-ray diffractometry. The results of each study are compared with data in the Data Base. In case of coincidence with one of the products with respect to all diagnostic features, the type of product and its source of origin are defined accordingly. If the features of the sample under analysis detected by the aforementioned methods do not coincide with any of the product types represented in Data Base, it is necessary to examine elemental composition and morphology of separate particle contained in the substance using SEM-EDX. If some particles characterized by features coinciding with features of particles belonging to any product or products from Data Base are found, this product or a mixture of products is assumed to be present in the composition of the substance under analysis. The assumption that the substance is a mixture can be verified by juxtaposing all previously determined features of the analyzed sample with the features of the pattern mixture (superposition) of the appropriate types of products represented in Data Base. Depending on the results of this verification the corresponding conclusion can be made.     

Chemical fingerprinting of adhesive tapes by GCMS detection of petroleum hydrocarbon products

Pressure-sensitive adhesive tapes often represent key evidence of crimes such as assault, rape or homicide; thus, the development of analytical techniques able to contribute to a detailed characterization of these materials is of forensic importance. The gas chromatography-mass spectrometry (GCMS) analysis of the solvent extractable fractions of a suite of electrical and gaffer adhesive tapes spanning a range of colors and manufacturers identified a number of petroleum-derived hydrocarbons. Molecular and isotopic analyses of hydrocarbon constituents of complex materials have found wide analytical utility including the forensic investigation of oil spills and arson. Here, we investigate the utility of these techniques for characterizing the hydrocarbon composition of pressure-sensitive adhesive tapes for forensic correlation purposes. Subtle distinction of tape samples was evident in the GCMS distribution of several hydrocarbon groups including alkyl-naphthalenes, hopane and sterane biomarkers. Linear discriminant analysis of the abundances of these products provided high level differentiation of tape manufacturer. The distinction of different adhesive tape samples was further extended by measurement of their stable carbon isotopic values. The molecular and isotopic differences of the petroleum content of tapes are consistent with the use of different petroleum materials used in the manufacturing process and demonstrate the benefits of the combined use of complementary oil hydrocarbon characterization approaches. This study reveals the forensic potential of using established petroleum characterization methods for characterizing materials with a petroleum-derived hydrocarbon element.     

Abuse of smoking methamphetamine mixed with tobacco: II. The formation mechanism of pyrolysis products

The pyrolysis products of smoking methamphetamine mixed with tobacco were determined by gas chromatography (GC) and GC/mass spectrometry (GC/MS) methods. The mainstream smoke contained methamphetamine (14.5% of the initial methamphetamine), phenylacetone (3.1%). N-cyanomethylmethamphetamine (1.9%), trans-beta-methylstyrene (1.7%), N-formylmethamphetamine (1.5%), and other products (each less than 1%). The amount of each pyrolysis product in the sidestream smoke was less than that in the mainstream smoke by a factor of over 5, except for methamphetamine (10.5%) and N-formylmethamphetamine (1.4%). The formation mechanism of these products was investigated, by use of a pyrolyzer, from the standpoint of the material, pyrolysis temperature, and pyrolysis atmosphere. Although several products (for example, dimethylamphetamine and trans-beta-methylstyrene) were formed by thermal self-decomposition of methamphetamine alone, most of the products, except N-cyanomethylmethamphetamine, were formed chiefly by the thermal reaction of methamphetamine with cigarette components. The formation of N-cyanomethylmethamphetamine required air and a high pyrolysis temperature. Air and a high pyrolysis temperature generally accelerated the formation of the pyrolysis products.     

Elucidation of a poisoning case from the analysis of formalin in which brain tissue was preserved

The toxicological analysis of post-mortem materials often help determine the cause of death. When tissues have been fixed in formalin it may be possible to extract several drugs from the tissue and/or the preserving fluid. An unusual case of multiple poisoning is discussed from the aspect of laboratory analysis.     

Microwave-assisted extraction and differential scanning calorimetry in the chemical identification of sliming agents apprehended in the south region of Brazil

Over the past decades, consume of slimming agents considerably increased in several countries, including Brazil, due to weight-loss and stimulant properties. Since these drugs are controlled to prevent illicit and indiscriminate use, there is a parallel illegal market that uses the Internet and irregular pharmacies in order to distribute these formulations. Slimming agents produced by these illegal sources are known for being manufactured with little or none quality control resulting in uncertain and unknown formulations. For forensic purposes, apprehended pharmaceuticals have to undergo a process of chemical identification that can be difficult due to its complex matrix. In this sense, application of assisted energies in the extraction step such as microwave irradiation can be a promising method to increase the recuperation of the target molecules of the sample. Therefore, the aim of this research was to identify four slimming agents apprehended in Brazil by means of visual inspection, Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry and Gas Chromatography – Mass Spectrometry. Moreover, the efficiency of solid-liquid extraction and microwave-assisted extraction was compared. It should be noted that our work was one of the few to use Differential Scanning Calorimetry and the application of microwave irradiation in the analysis of apprehended materials. Results showed that the majority of the samples was counterfeit being composed of one or several adulterants or contaminants. Initially, visual inspection resourcefully screened the slimming agents for possible signs of falsification, however it failed to detect fraudulent products that were very similar to veridical medicines. Sequentially, Fourier Transform Infrared Spectroscopy detected functional groups present in the samples while the presence or absence of the alleged active ingredients were successfully measured with Differential Scanning Calorimetry and, thus, providing a full chemical screening of the apprehended materials. Gas Chromatography- Mass Spectrometry confirmed the presence of adulterants such as caffeine, fluoxetine and phenolphthalein as well as contaminants such as sulfurol in the falsified samples. Finally, comparison of extraction procedures indicated that microwave-assisted extraction increased the recovery of compounds detected in chromatographic analysis to a greater extent than solid-liquid extraction.     

Analytical methods used for the discrimination of substances suspected to be bar soap: a preliminary study

The submission to forensic laboratories of unknown specimens suspected of being biological or chemical warfare agents has increased tremendously with the threat of terrorism. Oftentimes, a threatening correspondence that contains hoax materials is intended to make the recipient(s) believe they have been exposed to a toxin. In some cases, the perpetrator can use standard household products, such as detergents and soaps. Once these materials are received, they become forensic evidence and may be analyzed for identification and/or comparison with known seized material from a suspect(s). Two separate studies were conducted using different analytical protocols for bar soaps. In the first set, the forensic laboratory at the United States Secret Service conducted tests on 68 bars of soap using solid-phase microextraction and gas chromatography coupled with mass spectrometry. The 68 different soaps displayed unique total ion chromatogram profiles. Energy-dispersive X-ray analysis in conjunction with scanning electron microscopy was also used to characterize 46 of the 68 soaps as a preliminary study. In a second set of studies, as part of a homicide investigation, the laboratory at the California Department of Justice, Riverside, conducted examinations on 13 bars of soap by utilizing Fourier transform-infrared spectroscopy. The case study demonstrated that it is possible to distinguish some bar soaps using infrared analysis. Furthermore, the bar soaps could be distinguished from typical laundry detergents using this technique.