Arson

rapid oxidation process with the evolution of heat and light

sudden conversion of potential energy (chemical or mechanical) into kinetic energy with a production and release of gases under pressure - has both high order and low order

rapid pressure rise or high force explosion characterized by shattering the confining structure or container

a slow rate of pressurization or low-force explosion characterized by a pushing or dislodging the confining structure or container

certain machines used to analyze debris to identify ignitable liquid and explosive residues

ignitable liquid residues (ILR) must first be isolated from the debris into a gaseous or liquid phase

ignitable liquid residues

distillation solvent extraction headspace adsorption

obsolescence

destructive

nondestructive, screening technique

nondestructive, screening technique

most commonly used technique

GC is the most suitable technique for separation the detection of the analyte is achieved by utilizing Mass Spectrometry (MS) Gas chromatography is the preferred technique for separating the compounds in a complex mixture based on their boiling points. • The results are displayed as a graph showing a number of peaks, one scale depicts the amount of each component, the other the time taken for it to emerge from the instrument (Retention time) • Under the same conditions, the time taken for the component to emerge will always be the same.

complex chromatographic patterns can be simplified by passing the separated components through a mass spectrometer. the mass spectrometer fragments each component into a collection of ions each component has a unique collection of ions also referred to as its “chemical fingerprint”

a unique collection of ions

Ignitable liquids are usually composed of tens of hundreds of different compounds analyzing the extract begins with separating its components and then detecting them

most important, difficult and delicate step of fire debris analysis consists of reviewing and analyzing the data…determine whether or not an ignitable liquid is present characterize the liquid present in the debris…ASTM internaionl

eight evenly- spaced major peaks, with a number of minor intermediate peaks. 8 peaks are also present in a chromatogram of diesel but in different proportions. Diesel also contains an additional eight evenly- spaced peaks which emerge later from the instrument