Transcript 12.2 Notes - Techniques - Trimble County Schools

12.2 Notes - Techniques
Objectives
Understand the concept of antigenantibody interactions and how it is
applied to species identification and
drug identification
List and describe forensics tests used
to characterize a stain as blood
Immunoassay Techniques
Used for typing blood
Also used for detecting drugs
Combine the drug with a protein and
inject it back to the individual causing it to
produce antibodies
EMIT - Enzyme Multiplied
Immunoassay Technique
Used to detect drugs in urine
Antibodies added to sample
If present, specific drug is bound to the antibody
Enzyme labeled drug is added to urine and More
antibodies bind to that
Measure amount of enzyme labeled drug that is
bound
Value of the unbound antibodies is then used to
determine the concentration of the drug originally
in the urine
EMIT continued
Screening for marijuana (THC)
THC breaks down to substances
more easily excreted
Major metabolite is THC -9carboxylic acid
EMIT is used for that specific
metabolite
RIA – radioimmunoassay
Uses drugs with radioactive tags
Neither EMIT or RIA are drug
specific and must be used with a
reliable confirmation test
Characterization of Bloodstains
Is it blood?
From what species did it come?
If it is human, can it be
associated to a particular
individual?
12.1 & 12.2 Questions
1. What happens when serum containing B antibodies is added to
red blood cells carrying the B antigen? Will the same thing
happen if serum containing B antibodies is added to red blood
cells containing A antigen? Explain your answer
2. What is serology and what is its most widespread application?
In what other areas related to forensic science is it finding
application?
3. What is the difference between monoclonal and polyclonal
antibodies?
4. Briefly describe how antibodies capable of reacting with drugs
are produced in animals.
5. What immunoassay technique has gained widespread
popularity among toxicologists because of its speed and high
sensitivity for detecting drugs in urine? What drug is this
technique frequently used to screen for?
6. What three questions must the criminalist answer when
examining dried blood?