Effects of Fire Suppression Agents and Weathering in the Analysis of Fire Debris by HS-MS eNose.

In arson attacks the detection of ignitable liquid residues (ILRs) at fire scenes provides key evidence since ignitable liquids, such as gasoline, are commonly used to initiate the fire. In most forensic laboratories gas chromatography-mass spectrometry is employed for the analysis of ILRs. When a fire occurs, suppression agents are used to extinguish the fire and, before the scene is investigated, the samples at the scene are subjected to a variety of processes such as weathering, which can significantly modify the chemical composition and thus lead to erroneous conclusions.

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.

A new CE with contactless conductivity detection method for the determination of complex cationic compositions: Application to the analysis of pen inks.

A CE with contactless conductivity detection methodology using a novel background electrolyte for the separation and determination of 17 metal cations (Cs , Rb , K , Ca , Na , Mg , Mn , Sr , Li , Ba , Fe , Pb , Cd , Zn , Co , Cu and Ni ) and ammonium has been investigated. The buffer, based on lactic acid and β-alanine, was experimentally compared with other two commonly used electrolytes, showing important improvements, such as shorter analysis times (<11 min), better electrophoretic resolutions and higher detectabilities for certain analytes, such as Fe and Pb . The inclusion of other additives such as 18-Crown-6 and α-hydroxyisobutyric acid was studied in order to obtain the best separation of the analytes of interest.

Analytical tools for the analysis of fire debris. A review: 2008-2015.

The analysis of fire debris evidence might offer crucial information to a forensic investigation, when for instance, there is suspicion of the intentional use of ignitable liquids to initiate a fire. Although the evidence analysis in the laboratory is mainly conducted by a handful of well-established methodologies, during the last eight years several authors proposed noteworthy improvements on these methodologies, suggesting new interesting approaches. This review critically outlines the most up-to-date and suitable tools for the analysis and interpretation of fire debris evidence.

Study of Spectral Modifications in Acidified Ignitable Liquids by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy.

In this work, the spectral characteristics of two types of acidified gasoline and acidified diesel fuel are discussed. Neat and acidified ignitable liquids (ILs) infrared absorption spectra obtained by attenuated total reflection Fourier transform infrared spectroscopy were compared in order to identify the modifications produced by the reaction of the ILs with sulfuric acid. Several bands crucial for gasoline identification were modified, and new bands appeared over the reaction time.

Study of consumer fireworks post-blast residues by ATR-FTIR.

Specific analytical procedures are requested for the forensic analysis of pre- and post-blast consumer firework samples, which present significant challenges. Up to date, vibrational spectroscopic techniques such as Fourier transform infrared spectroscopy (FTIR) have not been tested for the analysis of post-blast residues in spite of their interesting strengths for the forensic field. Therefore, this work proposes a simple and fast procedure for the sampling and analysis of consumer firework post-blast residues by a portable FTIR instrument with an Attenuated Total Reflection (ATR) accessory.

Study of chemical modifications in acidified ignitable liquids analysed by GC-MS.

In this work, mixtures of gasoline with sulphuric acid and diesel fuel with sulphuric acid were analysed by gas chromatography-mass spectrometry (GC-MS). The results showed considerable qualitative and semi-quantitative modifications in the chromatographic profiles of the ignitable liquids (ILs). In the case of acidified gasoline, the alteration of the abundances of aromatic compounds and the hydrolysis of an oxygenated compound such as methyl tert-butyl ether (MTBE), in addition to the immediate and unexpected appearance of tert-butylated compounds were observed.

Analysis of pre-ignited improvised incendiary devices using portable Raman.

In this work, the use of a portable Raman spectrometer is evaluated for the non-invasive analysis of two types of pre-ignited improvised incendiary devices (IIDs), the classic Molotov cocktails and the chemical ignition Molotov cocktails (CIMCs). The most common ignitable liquids (ILs) used to make classic Molotov cocktails (gasoline, diesel fuel, kerosene and ethanol) were measured in seven different clear and colored glass bottles to evaluate if the container features could hamper the Raman measurements. The results showed that the portable Raman spectrometer can be employed to detect ILs in glass bottles without disturbances.

Study of acidified ignitable liquid residues in fire debris by solid-phase microextraction with gas chromatography and mass spectrometry.

The detection and identification of ignitable liquid residues in fire debris can be meaningful in fire investigations. However, background pyrolysis products and weathering hinder the identification and classification steps. In addition to those processes, the acidification of the ignitable liquids before the combustion process could make those tasks even more difficult.

Concurrent determination of anions and cations in consumer fireworks with a portable dual-capillary electrophoresis system.

A new automated portable dual-channel capillary electrophoresis instrument was built and applied to the concurrent determination of cations and anions. The system uses a single buffer and hydrodynamic injection of the sample is performed autonomously. A novel engraved flow-cell interface is used at the injection ends of the capillaries allowing the autonomous operation of the system.

Anions in pre- and post-blast consumer fireworks by capillary electrophoresis.

Consumer fireworks are a heterogeneous group of pyrotechnic items widely used by citizens around the world. There are a wide number of forensic cases related to consumer fireworks that require knowing their chemical composition and variety of designs to conduct accurate and comprehensive analyses. In this research paper, a selection of six consumer firework types (firecracker, rocket, pyrotechnic fountain, pyrotechnic battery, sparkler, and smoke bomb) is physically described and their anionic compositions are determined.