CHE 113 1 Forensic Toxicology and Alcohol. CHE 113 2 Paracelsus “What is there that is not a...

CHE 113 1

Forensic Toxicologyand Alcohol

CHE 113 2

Paracelsus

“What is there that is not a poison?

All things are poison and nothing without poison. Solely the dose determines that a thing is not a

poison.”

(1493-1541)

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

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What is Forensic Toxicology?

Toxicology: Study of drugs and poisons and their adverse affects on the human system. Subfields include:

pharmacokinetics (how the drug works on people) and

pharmacodynamics (how people work on the drugs)



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Drugs and Toxic Substances• Dose - amount of substance that enters the body• LD50 - Dose necessary to kill 1/2 of the population• Acute Toxicity - effects are immediate• Chronic Toxicity - effects occur over an extended

time• Species Specific: • Dioxin - polychlorinated organic compounds (many)

– From burning chlorinated compounds– Agent orange– Paper industry – Toxicity varies with species

O

OCl

Cl

Cl

Cl

Species LD50

Guinea Pig 0.0006Rabbit 0.115Hamster 3.5Monkey 0.07

CHE 113 5

Toxic SubstancesLD50 Calculations:

Cyanide (for 150 lb human - ~ 70 Kg)(70Kg)(10mg/Kg) = 700 mg (0.70g)

Nicotine (e.g.; from Cigarettes)(70Kg)(2 mg/Kg) = 140 mg (0.14g)(note 1 cig. = ~ 2 mg Nicotine)

Ethanol(70Kg)(1000mg/Kg) = 70,000mg (70g)

Effect of Body Weight: Ethanol150 lb Human = lethal dose = ~ 70 g40 lb Dog = lethal dose = ~ 20 g

Substance LD50

Aspirin 1750Ethanol 1000Morphine 500Caffeine 200Heroin 150Lead 20Cocaine 17.5Cyanide 10Nicotine 2Strychnine 0.8Batrachotoxin 0.002

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MSDS Sheets

• Materials Safety Data Sheets - provide specific toxicological, chemical and physical data about a compound.– Physical Properties and Names– Chemical Reactivities– Incompatibilities– Safe Handling– Toxicology (symptoms and means of exposure)– Safety and First Aid

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MSDS Sheets - ExampleNICOTINE (S)-3-(1-Methylpyrrolidin-2-yl)pyridine CAS # 54-11-5 3-(1-Methyl-2-pyrrolidinyl)pyridine RTECS # QS5250000 b-Pyridyl-a-N-methylpyrrolidine ICSC # 0519 1-Methyl-2-(3-pyridyl)pyrrolidine EC # 614-001-00-4 C10H14N2 Molecular mass: 162.2

TYPES OF ACUTE HAZARDS/ PREVENTION FIRST AID/HAZARD SYMPTOMS FIRE FIGHTING FIRE Combustible. Gives off irritating NO open flames. Powder, alcohol-resistant or toxic fumes (or gases) in a fire. foam, water spray, carbon

dioxide. EXPLOSION Above 95°C explosive vapor/air Above 95°C use a closed mixtures may be formed. system, ventilation. EXPOSURE PREVENT GENERATION OF MISTS! AVOID EXPOSURE OF (PREGNANT) WOMEN! IN ALL CASES CONSULT A DOCTOR! INHALATION Burning sensation. Nausea. Vomiting. Convulsions. Abdominal pain. Diarrhoea. Headache. Sweating. Weakness. Dizziness. Confusion. Ventilation, local exhaust, or breathing protection. Fresh air, rest. Refer for medical attention. SKIN MAY BE ABSORBED! Redness. Burning sensation

Protective gloves. Protective clothing. Remove contaminated clothes.Rinse and then wash skin with water and soap. Refer for medical attention.

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Forensic Toxicological Questions

• Intentional or Accidental Poisoning?• What type of Poison?

– Corrosive Poisons - Substances that actually destroy tissue outright

– Metabolic Poisons - Affect biochemical mechanisms.

• Drug Use - what drug, how much and when?• Activity while under the influence of drugs?



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Common Terms• Analyte - the compound that

you’re analyzing for.• Metabolite - Compound

formed from the metabolism of a drug. Heroin quickly metabolizes to Morphine so Morphine is a metabolite of Heroin.







Heroin Morphine

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CHE 113 11

Journals

• Journal of Analytical Toxicology

• Journal of Forensic Science

• Forensic Science International

• Journal of Chromatography (B)• British Medical Journal• Drug and Alcohol Dependence• International Journal of Legal Medicine



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Specimen Collection

Fluids: Organs:

Blood Skin

Urine Lungs

Vitreous Humor Hair and Fingernails

Oral Fluid Liver

Semen Kidney

Stomach Contents Bone

Bile Other (heart, brain, etc.)

Each has it’s own set of problems and advantagesEach has it’s own set of problems and advantages

Vitreous Humor - clear, gel-like mass that fills the space between the lens and the retina.

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Sampling• Blood - It matters where you sample in the body

– Blood taken near the liver or other solid organ may contain drug that has diffused from the organ into the blood post-mortem to give very high drug levels. Take blood from femoral artery because it’s far from organs.

• Urine - tends to concentrate compounds.– Can’t be sure of body concentration since it is unknown

how long it has been accumulating in the body.

• Liver - concentrates and stores drugs for long times.– good for detection but problematic for concentrations.

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Sampling• Bile - Useful for detection but not concentration.• Kidney - Similar to Bile.• Vitreous Humor - Correlates well with femoral

blood for most compounds.• Hair and Fingernails - Good for some compounds

with timelines possible.• Oral Fluids - Can be easily disguised.• Others - May be good for certain analyses but not

generally good sources for many compounds.

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Additional Matrices

Vomit Meconium

Earwax Amniotic Fluid

Semen Umbilical Cord Blood

Feces Milk

Sweat

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Specimen Collection: Case Examples

• Deceased– Suspected drug related death– Road Traffic Death– Murder

• Antecedent– Drink/drug driving– Drug Facilitated Sexual Assault (DFSA)– Professional/amateur athlete – Workplace drug testing

Dependent on the type of case and what samples are available

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Roles of Forensic Toxicology

• Postmortem Forensic Toxicology

• Human Performance Toxicology

• Forensic Drug Testing

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Postmortem Forensic Toxicology

• Death Investigation– Medical Examiners Office.– NYS - elected corners or appointed Medical

Examiners depending upon county.– Forensic Pathologist responsible for performing

autopsy.– Forensic Toxicologist responsible for analyzing

biological samples for poisons.

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Specimen Collection

• Essential to collect the appropriate specimens and that they are collected, packaged, transported, and stored correctly.

• Pathologist is responsible for the collection of the human-derived specimens and may consult the toxicologist on unusual cases.

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Specimen Collection

• MOST IMPORTANT STEP!!!!• Obtain a Representative Sample:

‘A small portion of a material taken from a bulk specimen and selected in such a way that it possesses the essential characteristics of the bulk’.

[E.g., easily possible to pick out a few crystals from a sample that do not reflect the majority of the sample - maybe that’s why they crystallized]

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Sample Handling

Storage

Avoid - loss (due to volatility).- contamination (e.g., insufficient seal).

Prevent - chemical interactions (e.g., Na and oil).

- Degradation (refrigerate biological samples).

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Sample Preparation

Homogenising - making the sample

uniform:

– grind (mortar and pestle)

– blender

– dissolution (water, solvents, acids)

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• Blood Samples– Usually the most important

specimen– Ideally 2 samples (25 mL

each)– Femoral/jugular (peripheral

site) - far as possible from solid organs

– Heart blood– Trunk blood

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Postmortem Toxicology• Vitreous humor samples - The clear, gel-like mass that

fills the space between the lens and the retina.

– Should be collected at all PM’s

– Relatively stable matrix

– Anatomically isolated area

– Good correlation with blood

– Easily obtained

Retina - The delicate lining at the back of the eye that functions much like the film in a camera. It receives light through the lens in your eye, forms that light into images, and sends those images to the brain, enabling you to see.

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Postmortem Toxicology• Urine samples:

– All available sample should be

collected.

– Higher concentrations present

than in other matrices, but not

always.

– Rapid tests available (both

qualitative [what] and

quantitative [how much] tests).

– Not always available.

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Postmorten Toxicology• Digestive System

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• Bile samples

– Alternative if urine unavailable

– Accumulation of drugs

– All available bile should be

collected

– Not an easy sample to analyzeBile is a thick digestive fluid secreted by the liver and stored in the gallbladder. It facilitates digestion by breaking down fats into fatty acids, which can be absorbed by the digestive tract.

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• Liver samples:

Drug metabolism occurs in the liver.

Drugs may be present in higher concentrations.

Metabolite Analysis.

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• Other specimens:

– Lung (volatiles)

– Spleen (carbon monoxide) – blood unavailable

– Stomach Contents (drug overdose)

– Hair ( drug use history)

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Human Performance Toxicology

• The effects of drugs on skills, acquisition, learning, and performance.

• Drugs may alter normal behavior by either enhancing or impairing performance.

• Stimulant drugs can enhance performance – short term but used regularly can impair performance.

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• Not only illicit drugs (e.g. heroin, cocaine, cannabis, etc…

• Prescription medication can impair performance especially at the start of the treatment– E.g. antidepressants, muscle relaxants, etc.

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Types of Abused Drugs• NarcoticsNarcotics - relief from pain and bring sleep. (now generally

means a socially unacceptable drug).– Narcotics are analgesic - relieve pain by depressing nervous system

(opium, morphine, heroin, codeine, opiates - oxycontin, methadone).• HallucinogensHallucinogens - alter normal thoughts, perceptions and moods

(PCP, LSD, mescaline, MDMA, ecstasy).• DepressantsDepressants - depress functions of central nervous system,

cause calm and bring about sleep (alcohol, barbituates). Tranquilizers are depressants.

• StimulantsStimulants - increase alertness and activity (cocaine, amphetamines).

• SteroidsSteroids - promote muscle growth (androgen, testosterone, anabolic steroids).

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Types of Abused Drugs• NarcoticsNarcotics - relief from pain and bring sleep. (now

generally means a socially unacceptable drug).– Narcotics are analgesic - relieve pain by depressing nervous

system (opium, morphine, heroin, codeine, opiates - oxycontin, methadone).

– Cocaine (stimulant), Marijuana (hallucinogen), etc are Not classified

as narcotics even though they are frequently called that.

– Most narcotics are opium derived.– Opium from Poppy plants (sap is 4 -

21% opium).

Opium PoppyOpium Poppy

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Hallucinogens• HallucinogensHallucinogens - alter normal thoughts, perceptions

and moods (PCP, LSD, mescaline, MDMA, ecstasy).

• Marijuana most common (derived from Cannabis or “hemp” plant).– Derive resin from plant secretions that is extracted with

organic solvents.– In use for 1000’s of years.– Brought to the US ca. 1920.

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Stimulants and Depressants

1. Caffeine

2. Amphetamine

3. Cocaine

1. Labrium2. Valium3. Methaqualone4. Ethyl Alcohol

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Steroids

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Steroids

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• Blood is the best specimen for determining impairment through drugs.

– In contact with the central nervous system.

– Hair/urine/sweat – becoming popular but

unlikely that a quantitative relationship will

exist.

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• Alcohol and/or Drugs Involving Driving:– In addition to collecting the correct samples,

additional information is essential:

• Witness statements to the incident

• Assessment of impairment at the scene

• Field Sobriety tests

• Drug Recognition Evaluation

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Forensic Drug Testing - Where?

• Workplace Drug Testing– Armed forces – Prisons– Private and public companies– Schools

• International Olympic Committee– Athletes

• Police Investigations– Arrestee– Drug Facilitated Sexual Assault (DFSA)

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Forensic Toxicology

• Sample Collection (uncontaminated)

• Specimen Identification (locate at crime scene)

• Storage

• Chain of Custody

• Analysis

• Reporting

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Forensic Toxicology

• Storage– Fridge/freezer– Preservative (EDTA in blood)– Leak proof– Suitable size– Prevent contamination

NN

CH2COOH

CH2COOH

HOOCH2C

CH2COOH

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Forensic Toxicology

• Chain of Custody:– Keeping tract of the control of the sample and

its handling from the time of collection until analysis done.

– Very important to be admissible in court.– Ensure procedures have been followed, seals

intact, signatures checked etc..

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CHE 113 45

Analytical Methods

• Qualitative Methods - What’s present?– GC-MS - Mass Spectrometry– Chemical Spot Tests - A test for a substance using reagents

that together generate an easily observed color or some other physical change in the presence of the target substance. Spot tests for blood, semen or certain drugs can be done at a crime scene, but often the positive results are indicative only, and need more sophisticated testing for court evidence.

• Quantitative Methods - How Much?– Spectrophotometric Methods - Infrared, UV-Vis.,

Nuclear Magnetic Resonance (NMR), others.

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Forensic Analysis - GC

CHE 113 47

Immunoassay

Immunoassay:Immunoassay: A technique utilizing antibodies to bind A technique utilizing antibodies to bind specifically to targeted substances in a specimen in specifically to targeted substances in a specimen in order to identify their presence.order to identify their presence.

AntibodyAntibody - Protein produced by the immune system of humans and higher animals in response to the presence of a specific antigen.AntigenAntigen - Substance that can trigger an immune response, resulting in production of an antibody as part of the body's defense against infection and disease. Many antigens are foreign proteins (those not found naturally in the body). An allergen is a special type of antigen which causes an antibody response.

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Immunoassay


EMIT - Enzyme Multiplied Immunoassay Technique

A competitive binding immunoassay that avoids the separation step. As Test antigen is increased it occupies more of the antibody molecules, so fewer of the enzyme labels are blocked. Substrate ---> product response increases.

TWO METHODSTWO METHODS

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Immunoassay


ELISA - Enzyme Linked Immunosorbent Assay - Wide application - diagnosis & research.

Non-competitive "sandwich" form requires two antibody-recognition sites on test antigen.

TWO METHODSTWO METHODS

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Monoclonal Antibodies• Polyclonal vs

Monoclonal

• Immortal supply of anti-protein sera



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Confirmation/Quantitation

Validated Method with Detailed SOP (Accepted Standard Operating Procedures)

Extraction Procedure

Chromatography

Gas and Liquid

Mass Spectrometry

Other Methods

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GC-MSREF100

15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00 55.00Time0

100

%

2020626 Scan EI+ TIC

1.67e731.73

19.17

33.71

42.18

41.44

46.23

42.98

53.91

47.20

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Reporting:

• Relationship of blood/urine alcohol

• Levels of blood/tissue drugs

• What do the metabolites indicate

• Involvement of alcohol/drugs

Opiates

What do free/ total opiate levels indicate

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APPROXIMATE DETECTION TIMES OF SOME COMMONDRUGS OF ABUSE IN URINE*

DRUGS DURATION OF DETECTION IN URINE:

Alcohol up to 1 dayAmphetamines (including MDMA, MDA) 1-3 daysBarbiturates 1-3 daysBenzodiazepines 1-3 daysCannabis up to 14 daysCocaine 1-3 daysCodeine 1-2 daysCyclizine 1-2 daysDihydrocodeine 1-2 daysHeroin (morphine) up to 1 dayMethadone 1-3 days6-MAM up to 1 day

CHE 113 55

Alcohol

• No. 1 Abused drug with more related deaths per year than any other.

• 5,000 to 10,000 year ago first prepared (guess).• 700 BC the Greeks had a thriving wine industry, and

by 200 BC the Romans had developed the art of wine making.

• Wine-making was concentrated around the warmer Mediterranean lands, while beer was mostly perfected in the cooler northern lands of Europe where it was too cold to grow grapes.

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Alcohols

• Organic Alcohols (R-OH)

– Methanol CH3OH (wood alcohol)

•More toxic than ethanol LD50 = 428 mg/Kg

– Ethanol C2H5OH (grain alcohol, EtOH)

•Lethal Dose LD50 (LD to 50% of the people) = 7060 mg/kg of body weight

•Brain- CNS depressant

– Propanol C3H7OH (isopropyl alcohol, rubbing alcohol) •More toxic than Ethanol (3600 mg/Kg)

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Ethanol• Colorless liquid with a

burning taste and a characteristic odour. Its RT density is 0.785 g/ml, and its boiling point is 78.4 C (F).

• Ethanol may be produced by oxidation of ethylene gas or fermentation of sugars.

• Ethyl alcohol can form hydrogen-bonds and exhibits intermolecular associations the same manner as water.

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Ethanol• Distilled alcohol always contains traces of water from the distillation mixture (4 to 6%). To obtain 99%+ alcohol, the water must be removed (unsuitable for consumption - denatured).

• Ethanol dissolves both in water and in organic solvents.

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Ethanol Drinks• Beverage alcohol is formed through fermentation of

products such as corn, potato mashes, fruit juices, and beet and cane sugar molasses.

• Fermentation is an enzymatically controlled anaerobic transformation of an organic compound - conversion of sugars to ethanol by microscopic yeasts in the absence of oxygen (or limited O2). The equation for the fermentation of glucose is:

C6H12O6 -----> 2CH3CH2OH + 2CO2

• Absorption of ethyl alcohol into the blood occurs mainly by ingestion but also can occur through the skin and via the lungs.

• Alcohol quickly equilibrated through all body water.

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Beer• Beer - produced from Barley steeped in water to

make it germinate (called Malt) - boiled with hops to produce flavor and aroma. The resultant liquid (called Wort) is then fermented. Various methods of production after the fermentation stage, produce the range of different beers we have today.

• Stronger beer is often referred to as Ale. Stout is sweeter and is flavored with roasted grain. Lager is a lighter beer that has been matured over a longer period. “Lite” beer has less alcohol (But how Light it Lite?).

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Beer

CHE 113 62

Cider

• Cider comes from apples that are reduced to a pulp which is then pressed to release the juice. This juice is then placed into vats, often with yeast added, to allow fermentation to take place. Sweet Cider is filtered to stop fermentation before all the sugar has been turned into alcohol. Traditional Sparkling Cider is allowed to continue fermenting in the bottle, although today, modern production methods mean that Ciders often have the 'fizz' injected by carbonation.

CHE 113 63

Wine• Made from Fermented Grapes:

– For red wines the skins are generally left in the mix after the fruit has been crushed so that during fermentation color from the skins seeps into the juice.

– For white wines the skins are discarded after crushing, and the grape solids are also removed before fermentation.

CHE 113 64

Other Alcoholic Drinks• BrandyBrandy. Brandy is distilled wine made from grapes. Other fruit

based liquors can be used (must be clearly identified. E.g.: Cherry Brandy). Brandy is aged in wooden casks until it is mature. Once it has been bottled however, it ceases to mature.

• GinGin. Made from malted barley and rye and usually flavored using juniper and other botanicals. (Occasionally it is made from corn or molasses).

• RumRum. Distilled from fermented sugar cane. Traditionally, Rum has a distinctive brown color, but Light Rum is also produced by rapid fermentation.

• WhiskeyWhiskey or or WhiskyWhisky. Made from fermented grain. Fermentation is started by adding yeast or the residue from previous fermentation before distillation.

• SherrySherry. Sherry is a fortified wine in which Brandy has been added to increase the alcohol content to 15.5% to 18%. [Sherry can only be produced in the Jerez Region in the southern Spain, and any similar products made elsewhere must be called 'Fortified Wine’].

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Ethanol Metabolism• Ingested alcohol - down the esophagus -

into the stomach - into the small intestine.

• Most alcohol absorbed in the stomach (approx. 20%) and the small intestine (approx. 80%).

• More alcohol will result in increased blood alcohol concentrations (BAC). A number of factors can influence ethyl alcohol absorption from the gastrointestinal tract. – Gastric emptying - the faster gastric emptying, the more rapid absorption. Food delays gastric emptying and therefore delays absorption of ethyl alcohol. The type of food does not seem to be a factor. Physical exercise also delays gastric emptying. Drugs (e.g. nicotine, marijuana, and ginseng), may modify physiological factors regulating gastric emptying.

CHE 113 66

Ethanol Metabolism• Following ingestion, about 20% of the ethanol is

rapidly absorbed through the stomach wall. At first, absorption is rapid but then the rate decreases even if gastric concentrations remain high.

• Absorption of alcohol through the small intestine is extremely rapid.

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Ethanol Metabolism• After absorption, alcohol diffuses throughout the body

and is fairly uniformly distributed in all tissues and fluids. – Ethanol crosses the placenta and gains free access

to fetal circulation.– It also crosses the blood brain barrier, thus the CNS

becomes an important target during alcohol intoxication.

– Alcohol can affect many functions: the literature shows pathological conditions on most body organs from chronic consumption.

– Alcohol first affects front of brain then moves to back (neurodepressant).

CHE 113 68

Alcohol and the Brain

Parietal LobeParietal Lobe - Ability to discriminate between sensory stimuli, ability to locate and recognize parts of the body, disorientation of environment space, ability to write.

Occipital LobeOccipital Lobe - Primary visual association area: Allows for visual interpretation.

Frontal LobeFrontal Lobe- Cognition and memory, ability to concentrate, judgment, inhibition, personality and emotional traits, language, and motor speech

Alcohol affects the brain front to back.Alcohol affects the brain front to back.

CHE 113 69

Alcohol affects the brain front to back.Alcohol affects the brain front to back.

CHE 113 70

Alcohol “Flow”

Esophagus

Stomach

Small Intestines

BloodBlood

Lungs, Urine Lungs, Urine and Skinand Skin

Body Body OrgansOrgans

Liver for Liver for OxidationOxidation

•Concentration of alcohol in tissues depends upon amount absorbed in blood.•Direct relationship between amount of alcohol excreted and blood alcohol levels.

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Ethanol Metabolism• 90 to 98% of the ingested drug is completely oxidized (CO2 and H2O). The

small amounts that remain are excreted unchanged in the breathbreath, urine and sweat. This process occurs mainly in the liver:

• CH3--CH2--OH + NAD+ ---> CH3--CHO + NADH + H+

• ethanol acetaldehyde

• Blood levels fall some 0.015 % w/v per hour (about 7.5 - 8.5 grams/hour) regardless of initial alcohol concentration.

• Nothing you can do will speed this process up...not exercising, vomiting, or drinking 30 glasses of espresso.

% w/v is g per 100 mL

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Alcohol Effects• Mild Intoxication (BAC = 0.050 %w/v) - Feeling of warmth, skin

flushed, impaired judgment, decreased inhibitions.

• Obvious Intoxication in most people (BAC = 0.100 %w/v) - Increased impaired judgment, inhibition, attention, slowed reflexes.

• Obvious Intoxication in all "normal" people (BAC = 0.150 %w/v) -

General lack of muscle coordination, slurred speech, double vision, memory and comprehension loss.

• Extreme intoxication (BAC = 0.250 %w/v) - Reduced responsiveness, inability to stand, vomiting, incontinence, sleepiness.

• Coma occurs around 0.350 %w/v and death is likely at 0.500 %w/v.

% w/v is g per 100 mL

CHE 113 73

Alcohol Effects

• Alcohol’s action on the brain produces of a number of behavioral effects. These effects are dependent upon the; – 1. amount of alcohol taken in.– 2. the time period over which the alcohol is drunk.– 3. whether other drugs are being taken at the same time.

– 4. the previous drinking history of the individual.– 5. the physical state of the person doing the drinking.

– 6. the genetic background of the individual( i.e. ethnicity, gender).

– 7. the mood and psychological makeup of the individual.

– 8. the environment when alcohol is taken.

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Alcohol Effects• “Hangover” Causes - 4 effects of ethanol:

– alcohol upsets your body's water balance. Causes “dry mouth” and thirst.– When alcohol is metabolized, it causes your blood to become more acidic

than normal (this is called acidosis). Causes nausea and sweating.– Alcohol alters the normal daily rhythm of certain body functions (loose

about 6 hours). – Alcoholic drinks contain certain impurities called congeners which can be

toxic. [vodka and gin have few congenes and are supposed to produce less of a hangover, whereas whisky and red wine, with lots of cogeners, are supposed to insure a big headache. Also a toxic byproduct of alcohol metabolism (acetaldehyde) builds in the bloodstream].

• Typical symptoms of hangover include nausea, ringing of the ears, headache, increased heart rate, excessive thirst, anxiety, insomnia, unsteadiness, dizziness (bed spins), diaphoresis (sweating), shakiness.

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Ethanol Testing • Specimen Acquisition

– Breath Test (alcohol)

– Blood sample (alcohol and drugs)

– Urine sample (alcohol and drugs)

• Collection– Breath – police officer at the scene– Blood – must be obtained by a medic (forensic medical

examiner)– Urine – collection must be observed

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Ethanol Testing

• FIELD SOBRIETY TESTING– Portable, roadside breath tester.– Walk and turn and/or one leg stand (divided attention test).

– Horizontal gaze nystagmus- involuntary jerking of eye as it moves to the side - more intoxicated the less the eye moves before jerking.

• Breath Testing

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Ethanol Testing• Breath Testing - direct relationship between BAC and

amount of alcohol vapor in breath.– Henry’s LawHenry’s Law - When a volatile compound is dissolved in a When a volatile compound is dissolved in a

liquid in equilibrium with the air, there is a fixed ratio liquid in equilibrium with the air, there is a fixed ratio between the concentration of the volatile compound in the air between the concentration of the volatile compound in the air and its concentration in the liquid (remains constant for a and its concentration in the liquid (remains constant for a fixed temperature).fixed temperature).

• When alcohol in blood is brought into equil. with air (lungs), there is a fixed ratio between the concentration of alcohol in air and the BAC.

• Measure the concentration of alcohol in air tells the BAC quite reliably.

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Ethanol TestingBreath Alcohol Testing: collects and measures alcohol content of alveolar breath.– Ratio of alcohol in the blood to alcohol in alveoli air is 2100 to 1 (1 mL of blood to 2100 mL of alveolar breath).

– Use Henry’s Law to determine BAC. – Determines BAC in pulmonary artery. May not be the same as venous blood but is most reflective of alcohol getting to the brain.

– Sectrophotometer measures absorption of light through potassium dichromate K2Cr2O7 .

– Alcohol reacts with dichromate so less dichromate means more alcohol. Indirect Method.Indirect Method.

– Some use infrared light to measure alcohol in chamber directly. Direct Method.Direct Method.

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Breathalyzer

Exhaled Breath

Piston

Sample Chamber(52.5 mL)

–Ratio of alcohol in the blood to alcohol in alveoli air is 2100 to 1 (1 mL of blood to 2100 ml of alveolar breath). Alcohol in 52.5 mL of exhaled air is equivalent amt. In 1/40 mL of blood.

3 mL of 0.025% K2CrO4

• Alcohol reacts with K2CrO4 to form acetic acid.

• Amount of K2CrO4 consumed is related to amount of alcohol present.

• Spec. determination of amount of K2CrO4 consumed.

• Determine alcohol content in sample.

• Calculate BAC.

CHE 113 80

Breathalyzer

–Silver nitrate is a catalyst–Sulfuric acid removes alcohol from the air–Reddish-orangeReddish-orange dichromate iondichromate ion changes color to the green chromium iongreen chromium ion when it reacts with the alcohol.

• Alcohol reacts with K2CrO4 to form acetic acid.

• Amount of K2CrO4 consumed is related to amount of alcohol presnt.

• Spec. determination of amount of K2CrO4 consumed.

• Determine alcohol content in sample.

• Calculate BAC.

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Legal Aspects

• Motor Vehicle Operation is not a Federal issue (each state determines).– Although, federal law now has 0.08 %w/v as legal limit (states must use or lose federal transportation funding).

• Blood Alcohol Content (BAC):– 0.10% w/v = 0.10g EtOH/100 mL blood (most states for limit under the influence).

– 0.08% is the NYS legal limit.– 0.04 %w/v for commercial drivers.

• Canada, UK 0.05 %w/v.• Sweden 0.02 5w/v.

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Legal Aspects• Federal Law - driving on road gives “implied consent”

for testing (either take test or lose license).• Schmerber v. California

– Pled 5th Amendment (not to self-incriminate).– Supreme court ruled against him, stating the 5th Amendment protects testimonial evidence not physical evidence - therefore, he had to give his blood for testing.

– Ruled against Schmerber on Search and seizure stating that blood sampling is an “emergency” procedure since by the time a search warrant was obtained the BAC would have dropped (destruction of evidence)

– Sample must be taken in a medically acceptable way without unreasonable force and related to an accident or arrest.

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End of ToxicologyEnd of Toxicology

CHE 113 1 Forensic Toxicology and Alcohol. CHE 113 2 Paracelsus “What is there that is not a...

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