Warm-Up
November 3, 2014
• What is important about the collection and
preservation of drugs?
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Objective
• SWBAT describe the process of infrared
spectroscopy.
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Agenda
1.
2.
3.
4.
5.
6.
Crime 360
Alcohol
Infrared Spectroscopy
Mouse Activity
Pablo Escobar Documentary
Exit Slip
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How Stuff Works
Dr. G Toxicology Video
T. Trimpe 2008 http://sciencespot.net/
Watch the video and then answer the questions.
http://videos.howstuffworks.com/discovery-health/4883-dr-g-toxicology-video.htm
1. When are samples taken for a toxicology screen?
A. At the crime scene
B. At the morgue
C. After the autopsy
2. What body fluid do they test for alcohol, glucose, and other drugs?
A. Blood
B. Hair samples
C. Saliva
3. What organs do they often taken fluid from for testing?
A. Lungs
B. Bones
C. Eyes
4. What type of scientist is Dr. G?
A. Forensic technician B. Medical Examiner
C. Crime Scene Investigator
The answers are …
1. When are samples taken for a toxicology screen?
A. At the crime scene
B. At the morgue
C. After the autopsy
2. What body fluid do they test for alcohol, glucose, and other drugs?
A. Blood
B. Hair samples
C. Saliva
3. What organs do they often taken fluid from for testing?
A. Lungs
B. Bones
C. Eyes
4. What type of scientist is Dr. G?
A. Forensic technician B. Medical Examiner
C. Crime Scene Investigator
Drunk Driving
• Over 31% of traffic deaths in the United
States were related to alcohol in 2010.
• Traditional roadside testing methods do
not confirm that a driver is over the legal
blood alcohol content limit.
• Officers utilize portable Breathalyzers to
quantify the amount of alcohol in the
suspect’s blood.
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What is Alcohol?
• Alcohol is a clear liquid at room
temperature.
• Alcohol is less dense and evaporates at a
lower temperature than water (this
property allows it to be distilled -- by
heating a water and alcohol mixture, the
alcohol evaporates first).
• Alcohol dissolves easily in water.
• Alcohol is flammable (so flammable that it
can be used as a fuel).
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What is Alcohol?
•
H
H3 C - C - O - H
H
• Ethyl Alcohol-Ethanol
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What next?
• Alcohol is dissolved in the water of the
blood.
• Blood carries alcohol throughout the body
• Dissolves in the water of each tissue
(except fat…can’t dissolve in fat tissue!)
• Once inside tissues, exerts its effects on
the body!
• BAC=Blood Alcohol Concentration
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How does alcohol leave the body?
• The kidney eliminates 5 percent of alcohol in
the urine.
• The lungs exhale 5 percent of alcohol, which
can be detected by breathalyzer devices.
• The liver chemically breaks down the
remaining alcohol into acetic acid.
• *the body can break down .5oz of alcohol/hr
– It would take 1 hour to break down 1 beer!
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Stages of Drinking
• Euphoria (BAC=0.03-0.12)
**Legally Drunk: BAC=0.08
•
•
•
•
•
Excitement (BAC=0.09-0.25)
Confusion (BAC=0.18-0.30)
Stupor (BAC=0.25-0.40)
Coma (BAC=0.35-0.50)
Death (BAC more than 0.50)
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SFST=Standardized Field Sobriety
Tests
81-91% effective when used together!
• Horizontal gaze nystagmus (following an
object or a light with your eyes)
• One leg stand (also called “one legged
stand”, standing with one leg raised about
6 inches off the ground)
• Walk and turn, or “heel to toe” (walking in
a straight line, turning and walking the
other way, heel to toe)
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Alcohol Testing
• Alcohol intoxication is legally defined by
the blood alcohol concentration (BAC)
level.
• Taking a blood or urine sample in the field
for later analysis in the laboratory is not
practical or efficient for detaining drivers
suspected of driving while impaired (DWI)
or driving under the influence (DUI).
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Alcohol Absorption and Evaporation
• Alcohol gets absorbed from the stomach and intestines
into the bloodstream.
• Alcohol is not chemically changed in the bloodstream.
• As the blood goes through the lungs, some of the
alcohol moves across the membranes of the lung's air
sacs into the air, because alcohol will evaporate from a
solution.
• The concentration of the alcohol in the lungs is related
to the concentration of the alcohol in the blood with a
ratio of 1 to 2100.
• It can be detected by breath alcohol testing devices,
such as a Breathalyzer.
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Legal Limit
• The American Medical Association says that
a person can become impaired when the
blood alcohol level hits 0.05.
• If a person's BAC measures 0.08, it means
that there are 0.08 grams of alcohol per 100
ml of blood.
• As of 2004, all 50 U.S. States have adopted
the 0.08 standard for drunkenness, with
lower limits for some classes of offenders
like truck drivers or those under 21.
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Sobriety Testing
• Usual procedure is a field test for sobriety followed by
retesting in the police station with a more accurate
machine.
• The field test can be a less accurate breath test, while
the confirmatory test is legally admitted to court and
more accurate.
• In some states the suspect may elect to forgo the field
test and be tested at the police station instead.
• A urine test (preferred for drug use) or blood alcohol
may also be obtained. These tests are admitted in
court.
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Types of Testing Devices
• Two breath testing technologies are most prevalent.
• Desktop analyzers generally use infrared
spectrophotometer technology, electrochemical fuel
cell technology, or a combination of the two.
• Hand-held field testing devices are generally based
on electrochemical platinum fuel cell analysis and,
depending upon jurisdiction, may be used by
officers in the field as a form of "field sobriety test"
or as evidential devices in point of arrest testing.
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Breath Tests
• A breath test reflects the alcohol
concentration in the pulmonary artery.
• One instrument used for breath tests is
called The Breathalyzer.
• The Breathalyzer is a device for collecting
and measuring the alcohol content of
alveolar breath.
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Three Tests
• Breathalyzer
• Infrared
• Fuel Cell
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The Breathalyzer
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The Breathalyzer
• The Breathalyzer traps 1/40 of 2100
milliliters of alveolar breath.
• Since the amount of alcohol in 2100
milliliters of breath approximates the
amount of alcohol in 1 milliliter of blood—
the Breathalyzer in essence measures
the alcohol concentration present in
1/40 of a milliliter of blood.
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Breathalyzer
• Once the alveolar breath is trapped it is
allowed to undergo a chemical reaction:
•
2K2Cr2O7 + 3C2H5OH + 8H2SO4  2Cr2(SO4)3 + 2K2SO4 + 3CH3COOH + 11H2O
Potassium
dichromate
Ethyl
alcohol
Sulfuric
acid
Chromium
sulfate
Potassium
sulfate
Acetic
acid
Dihydrogen
oxide
• The Breathalyzer indirectly determines the quantity of alcohol
consumed by measuring the absorption of light by potassium
chromate before and after its reaction with alcohol, using the
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Other Breath Tests
• Infrared breath-testing instrument
• Fuel cell
• Note: These instruments are used more
recently because they don’t depend upon
chemical reagents and are entirely
automated.
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Infrared-Breath Test
• Uses the principle that infrared light is absorbed
when shined on alcohol
• Essentially, the infrared light passes through a
chamber where it will interact with the alcohol
and cause the light density to decrease.
• The decrease in light intensity is proportional to
the concentration of alcohol present in the
captured breath
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Fuel Cell—Breath Test
• A fuel cell converts a fuel and an oxidant
into an electrical current.
• In this test, the breath alcohol is the fuel
and atmospheric oxygen acts as the
oxidant.
• Alcohol is converted, generating a current
that is proportional to the quantity of
alcohol present in the breath.
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Infrared and Fuel Cell Breath Tests
• Infrared Breath Test
uses infrared
wavelengths to test for
alcohol or other
interferences in the
breath
• Fuel Cell Test
converts fuel
(alcohol) and
oxygen into a
measurable electric
current
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Breathalyzers
•
•
•
•
Ethanol is known to absorb infrared light.
Infrared light is passed through a chamber.
You breathe into the chamber
If less infrared light passes through, we
know it’s because it was absorbed by the
ethanol in your breath.
• The higher the absorption rate, the higher
your BAC.
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Problems with Breathalyzers
• Can’t distinguish between ethanol,
acetone (diabetics/atkins diet), etc.
– Lawyers will make cases against:
• Maintenance of breathalyzers
• Radio frequency interference
• Person having a reading near .08, people process
alcohol differently
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Fuel Cell Testing Method
• The fuel cell uses a chemical reaction to generate an
electrical signal in response to the breakdown of alcohol in
the fuel cell.
• The fuel cell converts alcohol and water into acetic acid, H+,
and e- at the anode.
• At the cathode, H+ and e- combine with atmospheric oxygen
to regenerate the water. This net reaction involves a flow of
electrons from anode to cathode.
• The electron flow is measured and the signal is displayed on
the readout.
• More alcohol releases more electrons.
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Infrared Spectroscopy
• All substances absorb some infrared
radiation at particular wavelengths
because of the arrangement of their
chemical bonds.
• The infrared spectrum of an unknown
compound can be compared to known
spectra in order to identify the unknown
compound.
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Infrared Spectroscopy
The infrared source is
split into two beams
with mirrors. These
shine through both
the reference and
unknown sample.
IR source
Reference
Sample
Unknown
Sample
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Infrared Spectroscopy
The beams hit a
chopper which
alternately allows
each beam to pass
so that one beam is
always blocked.
IR source
Reference
Sample
Unknown
Sample
Chopper
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Infrared Spectroscopy
One beam passes
through the chopper
and hits a prism.
This separates the
light into its
component
wavelengths
IR source
Reference
Sample
Unknown
Sample
Chopper
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Infrared Spectroscopy
A slit allows only a
small range of
wavelengths to hit the
detector. The slit and
detector move
together to
individually sample
each wavelength.
IR source
Reference
Sample
Unknown
Sample
Chopper
Detector
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Infrared Spectroscopy
When every
wavelength has been
absorbed from both
samples they are
plotted against each
other for
identification.
IR source
Reference
Sample
Unknown
Sample
Chopper
Detector
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Infrared Spectroscopy
Post-processing can
compare the
differences in the
signal to quantify
alcohol content.
IR source
Reference
Sample
Unknown
Sample
Chopper
Detector
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Ethanol Spectral Analysis
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Factors Affecting Blood Alcohol Tests
• Drinking on empty stomach (faster
metabolism)
• Drinking with a fever (false positive)
• Using mouthwash or breath spray (false
positives)
• No good way to spoof the systems.
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Parts of the brain affected by Alcohol
• Alcohol 1st
affects the
forebrain and
moves
backward
• Last affected
is medulla
oblongata
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Alcohol
and the Law
• 1939-1964: intoxicated =
0.15% BAC
• 1965: intoxicated = 0.10%
BAC
• 2003: intoxicated = 0.08%
BAC
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Alcohol and the Law
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SO…..How does Alcohol pertain to
Forensics?
• 42% of all violent crimes involve alcohol
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Mouse Activity
• http://learn.genetics.utah.edu/content/addi
ction/
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Pablo Escobar Documentary
24. Where did Pablo want to send his family and how
did the U.S find out? What was the result?
25. What was the mistake that Pablo made that
caused the authorities to get close to Escobar?
26. What happened when the search block made a
raid and why was there a mistake?
27. How was Pablo killed?
28. What caused uproar in Columbia?
29. What is the official version of Pablo’s death?
30. Why do some people think he was shot up
close?
31. What is the AUC and what have they been
responsible for?
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Homework
• Read Chapter 6, pages 221-230
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Exit Slip
November 3, 2014
• Go to m.socrative.com and enter 417101
• Question: How does infrared spectroscopy
work?
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