FORENSIC CHEMISTRY (Lab)

• Health and Safety Procedures 


  Most important issues to be considered when arriving at crime scenes.
• TRUE OR FALSE: It might be necessary to suppress or remove health and safety hazards before starting the investigation.

  TRUE
• Chemical Labels consist of:

  • Chemical name
  • CAS number
  • UN number
  • Chemical and hazard warning symbols
• Safety Data Sheets (SDS)  

  Provides detailed information about a chemical product’s composition and its potentially harmful effects, along with instructions on how to store, handle, and dispose of the substance safely.
• Globally Harmonized System (GHS)

  Current system of classification which indicated hazards and the warning symbols for a chemical.
• Types of GHS

  • Health and physical hazard pictograms

  Transport pictograms for dangerous goods
• Health and Physical Hazard Pictograms   

  • Indicate the multiple risks which may be associated with a chemical.
• Health and Physical Hazard Pictograms   


  Help to determine what physical protection measure might be required, such as a chemical suit, apron, and gloves (as the chemical is corrosive) and respiratory and face protection (as it is an irritant).
• FLAMMABLE

  Acetone

  Acetic anhydride

  Petroleum ether

  Sodium metal
• OXIDIZING

  Petroleum permanganate

  Sodium hypochlorite
• Transport Pictograms   

  Identify chemicals which are classed as dangerous goods and classifies them into different groups based on their chemical properties and reactivity.
• LEVEL D

  Ø  Protection is primarily a work uniform.

  Ø  Used for nuisance contamination only.

  Ø  Requires only coveralls and safety shoes/boots.

  Ø  Other PPE is based upon the situation (e.g., types of gloves)

  Ø  Should not be worn on any site where respiratory or skin hazards exist.
• LEVEL C


  Protection should be selected when the type of airborne substance is known, concentration measured, criteria for using air-purifying respirators met, and skin and eye exposure is unlikely.
• LEVEL C

  Periodic monitoring of the air must be performed.
• LEVEL C

  • Full-face or half-mask, air-purifying respirator (NIOSH approved).

  Chemical resistant clothing (one piece coverall, hooded two-piece chemical splash suit, chemical resistant hood and apron, disposable chemical resistant coveralls).
• LEVEL B

  Protection should be selected when the highest level of respiratory protection is needed, but a lesser level of skin and eye protection is needed.
• LEVEL B

  At minimum level recommended on initial site entries until the hazards have been further identified and defined by monitoring, sampling, and other reliable methods of analysis, and equipment corresponding with those findings utilized.
• LEVEL B

  Positive-pressure (pressure-demand), self-contained breathing apparatus, or positive-pressure supplied air respirator with escape SCBA.
• LEVEL B

  • Chemical resistant clothing (overalls and long-sleeved jacket, coveralls, hooded two-piece chemical splash suit, disposable chemical resistant coveralls).
  • Gloves, outer and inner, chemical resistant.
  • Boots, outer, chemical resistant, steel toe and shank.
• LEVEL A

  Protection should be worn when the highest level of respiratory, skin, eye, and mucous membrane protection is needed.
• LEVEL A

  • Positive pressure (pressure-demand), self-contained breathing apparatus (SCBA) (NIOSH approved), or positive-pressure supplied air respirator with escape SCBA.
  • Fully encapsulating chemical protective suit.
• LEVEL A

  • Gloves, inner, chemical resistant.
  • Gloves, outer, chemical resistant.
  • Boots, chemical resistant, steel toe and shank; (depending on suit boot construction, worn over or under suit boot.)
• Safe Handling and Transport of Chemicals    

  1. Before moving chemicals, try to identify the type of chemical and any hazards. Note that on occasions, chemicals are deliberately mislabeled for smuggling or trafficking purposes, and caution should be used as hazard labels may not be reliable.
• Safe Handling and Transport of Chemicals    


  Second. Labels can vary greatly, however, the hazard class is normally the dominant, or largest warning symbol visible.
• Safe Handling and Transport of Chemicals    


  Third. Assess the condition of the containers, “Is it safe to move, is it rusted, leaking or damaged?” As labels may not always be reliable, it is critical that containers or drums be in good condition and securely sealed to reduce the potential for accidental reactions during handling or transport.
• Safe Handling and Transport of Chemicals    

  Fourth.  Note that unsafe or damaged containers should not be transported and should be managed at the location or decanted (transferred) to another suitable drum or container.
• Safe Handling and Transport of Chemicals    

  Fifth. Minimize chemical movements, plan what to move, how to move it, and where it is going to be moved to. Make sure the way is clear, that there are no physical obstacles and that all non-essential personnel are safe distance away.
• Safe Handling and Transport of Chemicals    

  Sixth. To ensure prompt assistance in case of accident during the handling and removal of chemicals, such exercises should be conducted by at least two people, equipped with the same level of PPE.
• Safe Handling and Transport of Chemicals    


  Seventh. Transport chemicals separately with only chemicals from the same hazard class transported together in any load.
• Microscopes

  Analytical tools that are used to visualize different evidence or samples of forensic significance.
• Microscopes

  Used to observe and analyze features of evidence items that are not visible or cannot be clearly observed with the naked eye.
• Each wave has:

  1. Amplitude
  2. Wavelength
• What is Amplitude?


  A measure of the height of the wave.
• What is Wavelength?

  The distance between the end point of one wave and the start point of the next one.
• What is included in a light wave?

  Intensity, velocity, wavelength, frequency, amplitude, vibration, direction, and phase.
• How is the energy (€) of a wave computed?

  By multiplying Planck’s constant (h) times the speed of light (c) and dividing by the wavelength (λ).
• Light can be refracted. What does this mean?

  A measure of the bending of light.
• What does it mean when light is dispersed?

  Describes the property of separating the wavelengths of light.
• What are polarized light waves?

  Light waves in which the vibrations occur in a single plane.
• Microscopes Commonly Used in Forensics        

  • Compound Microscope
  • Stereoscopic Microscope
  • Comparison Microscope
  • Polarizing Microscope
  • Microspectrophotometer