warm-up november 3, 2014

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Warm-UpNovember 3, 2014

• What is important about the collection and preservation of drugs?


Objective

• SWBAT describe the process of infrared spectroscopy.


Agenda

1. Crime 360

2. Alcohol

3. Infrared Spectroscopy

4. Mouse Activity

5. Pablo Escobar Documentary

6. Exit Slip

T. Trimpe 2008 http://sciencespot.net/

How Stuff WorksDr. G Toxicology Video

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

Watch the video and then answer the questions.http://videos.howstuffworks.com/discovery-health/4883-dr-g-toxicology-video.htm

http://videos.howstuffworks.com/discovery-health/4883-dr-g-toxicology-video.htm

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 …


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.


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).

http://science.howstuffworks.com/h2o.htm


What is Alcohol?

• HH3 C - C - O - H H

• Ethyl Alcohol-Ethanol


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


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!

http://science.howstuffworks.com/kidney.htm

http://science.howstuffworks.com/lung.htm

http://science.howstuffworks.com/breathalyzer.htm


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)


SFST=Standardized Field Sobriety Tests81-91% 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)


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).


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.


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.


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.


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.


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.


Three Tests

• Breathalyzer

• Infrared

• Fuel Cell


The Breathalyzer


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.


Breathalyzer

• Once the alveolar breath is trapped it is allowed to undergo a chemical reaction:

• 2K2Cr2O7 + 3C2H5OH + 8H2SO4 2Cr2(SO4)3 + 2K2SO4 + 3CH3COOH + 11H2O

• 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 principle of spectrophotometry

Potassium dichromate

Ethyl alcohol

Sulfuric acid

Chromium sulfate

Potassium sulfate

Acetic acid

Dihydrogen oxide


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.


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


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.


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


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.


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


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.


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.



The infrared source is split into two beams with mirrors. These shine through both the reference and unknown sample.

IR source

ReferenceSample

Unknown Sample



The beams hit a chopper which alternately allows each beam to pass so that one beam is always blocked.

IR source

ReferenceSample

Unknown Sample

Chopper



One beam passes through the chopper and hits a prism. This separates the light into its component wavelengths

IR source

ReferenceSample

Unknown Sample

Chopper



A slit allows only a small range of wavelengths to hit the detector. The slit and detector move together to individually sample each wavelength.

Detector

IR source

ReferenceSample

Unknown Sample

Chopper



When every wavelength has been absorbed from both samples they are plotted against each other for identification.

Detector

IR source

ReferenceSample

Unknown Sample

Chopper



Post-processing can compare the differences in the signal to quantify alcohol content.

Detector

IR source

ReferenceSample

Unknown Sample

Chopper


Ethanol Spectral Analysis


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.


Parts of the brain affected by Alcohol

• Alcohol 1st affects the forebrain and moves backward

• Last affected is medulla oblongata


Alcohol and the Law

• 1939-1964: intoxicated = 0.15% BAC

• 1965: intoxicated = 0.10% BAC

• 2003: intoxicated = 0.08% BAC


Alcohol and the Law


SO…..How does Alcohol pertain to Forensics?

• 42% of all violent crimes involve alcohol


Mouse Activity

• http://learn.genetics.utah.edu/content/addiction/

http://learn.genetics.utah.edu/content/addiction/

http://learn.genetics.utah.edu/content/addiction/


Pablo Escobar Documentary24. 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?


Homework

• Read Chapter 6, pages 221-230


Exit SlipNovember 3, 2014

• Go to m.socrative.com and enter 417101• Question: How does infrared spectroscopy

work?

warm-up november 3, 2014

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