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1 f arson explosives

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San Raj

Forensic arson investigations involve isolating and analyzing flammable residues and explosive materials from fire scenes. Accelerants are substances used to start or spread fires. In investigations, evidence is collected from totally burned, partially burned, and unburned areas for comparison. In the lab, common methods like steam distillation, solvent extraction, and charcoal vapor concentration are used to isolate and concentrate accelerants. Gas chromatography/mass spectrometry is then used to analyze the composition of the accelerants and determine what was used through identifying its breakdown products.

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Forensic Arson andForensic Arson and Explosive InvestigationsExplosive Investigations
Forensic Arson and ExplosiveForensic Arson and Explosive InvestigationsInvestigations Two Main Areas of Interest: isolation and analysis of flammable residues collection and analysis of explosive material Any flammable liquid or substance used to start and/or maintain a fire is known as an accelerant Not all flammable or explosive material will burn in a fire accelerants always get trapped in pores in material and will not burn
The Chemistry of FireThe Chemistry of Fire Fire is the product of combustion - the rapid combination of oxygen with another substance accompanied by the production of light and heat Two Important Points: Most combustion reactions will not happen by themselves (they are not spontaneous).they need help getting started The energy released comes from the breaking and reforming of the bonds that hold the compounds together
Accelerants and ExplosivesAccelerants and Explosives Accelerants and explosives are almost always organic in nature (wood, gasoline, kerosene, paper, etc) If an organic molecule burns completely, the products are always carbon dioxide and water. Smoke, ash, carbon monoxide result from incomplete combustion. Explosive materials are often compounds that are chemically unstable they want to react and form more stable molecules
Investigating Arson or BombingsInvestigating Arson or Bombings Steps to Follow: 1. Begin collecting evidence as soon as possible. 2. Collect totally burned, partially burned, and unburned samples from the scene for comparison 3. Back in the forensic lab, isolate and concentrate the accelerant material - there are four common methods used to isolate and concentrate this material 4. Analyze the material to determine its composition
Investigating Arson or BombingsInvestigating Arson or Bombings Steps to Follow: 1. Begin collecting evidence as soon as possible. 2. Collect totally burned, partially burned, and unburned samples from the scene for comparison 3. Back in the forensic lab, isolate and concentrate the accelerant material - there are four common methods used to isolate and concentrate this material 4. Analyze the material to determine its composition
Methods for Isolating and ConcentratingMethods for Isolating and Concentrating AccelerantsAccelerants a. Steam Distillation b. Solvent Extraction c. Head Space Analysis d. Vapor Concentration on Charcoal e. Solid Phase Extraction
Methods for Isolating and ConcentratingMethods for Isolating and Concentrating AccelerantsAccelerants a. Steam Distillation b. Solvent Extraction c. Head Space Analysis d. Vapor Concentration on Charcoal e. Solid Phase Extraction
Analyzing the ResultsAnalyzing the Results Arson labs often use a method called gas chromatography/mass spectrometry (GC/MS) to determine the composition of the accelerants or explosives found GCGCMSMS
Analyzing the ResultsAnalyzing the Results Important Parts of a Gas Chromatograph: injection port and vaporization chamber column usually inside coated with non-polar material a carrier gas to push accelerant molecules through the column a detector (usually this is the mass spectrometer)
Analyzing the ResultsAnalyzing the Results Important Parts of a Mass Spectrometer: ionizing chamber analyzer tube detector
Analyzing the ResultsAnalyzing the Results
Analyzing the ResultsAnalyzing the Results
Analyzing the ResultsAnalyzing the Results Ion Mobility Spectrometer vaporize with heat ionize the sample with electrons detect by how fast they move in an electric field

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1 f arson explosives

  • 1. Forensic Arson andForensic Arson and Explosive InvestigationsExplosive Investigations
  • 2. Forensic Arson and ExplosiveForensic Arson and Explosive InvestigationsInvestigations Two Main Areas of Interest: isolation and analysis of flammable residues collection and analysis of explosive material Any flammable liquid or substance used to start and/or maintain a fire is known as an accelerant Not all flammable or explosive material will burn in a fire accelerants always get trapped in pores in material and will not burn
  • 3. The Chemistry of FireThe Chemistry of Fire Fire is the product of combustion - the rapid combination of oxygen with another substance accompanied by the production of light and heat Two Important Points: Most combustion reactions will not happen by themselves (they are not spontaneous).they need help getting started The energy released comes from the breaking and reforming of the bonds that hold the compounds together
  • 4. Accelerants and ExplosivesAccelerants and Explosives Accelerants and explosives are almost always organic in nature (wood, gasoline, kerosene, paper, etc) If an organic molecule burns completely, the products are always carbon dioxide and water. Smoke, ash, carbon monoxide result from incomplete combustion. Explosive materials are often compounds that are chemically unstable they want to react and form more stable molecules
  • 5. Investigating Arson or BombingsInvestigating Arson or Bombings Steps to Follow: 1. Begin collecting evidence as soon as possible. 2. Collect totally burned, partially burned, and unburned samples from the scene for comparison 3. Back in the forensic lab, isolate and concentrate the accelerant material - there are four common methods used to isolate and concentrate this material 4. Analyze the material to determine its composition
  • 6. Investigating Arson or BombingsInvestigating Arson or Bombings Steps to Follow: 1. Begin collecting evidence as soon as possible. 2. Collect totally burned, partially burned, and unburned samples from the scene for comparison 3. Back in the forensic lab, isolate and concentrate the accelerant material - there are four common methods used to isolate and concentrate this material 4. Analyze the material to determine its composition
  • 7. Methods for Isolating and ConcentratingMethods for Isolating and Concentrating AccelerantsAccelerants a. Steam Distillation b. Solvent Extraction c. Head Space Analysis d. Vapor Concentration on Charcoal e. Solid Phase Extraction
  • 8. Methods for Isolating and ConcentratingMethods for Isolating and Concentrating AccelerantsAccelerants a. Steam Distillation b. Solvent Extraction c. Head Space Analysis d. Vapor Concentration on Charcoal e. Solid Phase Extraction
  • 9. Analyzing the ResultsAnalyzing the Results Arson labs often use a method called gas chromatography/mass spectrometry (GC/MS) to determine the composition of the accelerants or explosives found GCGCMSMS
  • 10. Analyzing the ResultsAnalyzing the Results Important Parts of a Gas Chromatograph: injection port and vaporization chamber column usually inside coated with non-polar material a carrier gas to push accelerant molecules through the column a detector (usually this is the mass spectrometer)
  • 11. Analyzing the ResultsAnalyzing the Results Important Parts of a Mass Spectrometer: ionizing chamber analyzer tube detector
  • 14. Analyzing the ResultsAnalyzing the Results Ion Mobility Spectrometer vaporize with heat ionize the sample with electrons detect by how fast they move in an electric field