1 Chem 113, Prof. J.T. Spencer Chapter 13 Forensic Chemistry Dr. J. T. Spencer Adjunct T. L. Meeks

11

Chem 113, Prof. J.T. SpencerChem 113, Prof. J.T. Spencer

Chapter 13Chapter 13Forensic ChemistryForensic Chemistry

Dr. J. T. SpencerAdjunct T. L. Meeks

22


Learning ObjectivesLearning Objectives

Forensic Toxicology deals with both how drugs and poisons both act upon our bodies and how our bodies respond and act upon the foreign chemical…

33



Pharmacokinetics and how a drug/poison works on a person

Pharmacodynamics and how a drug/poison is worked on by a person

What are drugs, medicines, poisons, and toxins

What is meant by toxicity and how is it measured

What is a typical pathway of a drug through the body and what is ADME

44



How drugs and poisons can be metabolized

How new drugs are discovered and what is meant by “off--‐label” uses

What is meant by a corrosive and a metabolic poison and how they work

What is the scope and nature of the worldwide drug problem

What are narcotics, hallucinogens, stimulants, depressants, and steroids

55



What are the pharmacodynamics and pharmacokinetics of these drugs

What are club drugs and what is meant by Drug‐Facilitated Sexual Assault (DFSA)

What is the Controlled Substance Act and how are drugs placed into Schedules

What are the chemical properties of ethanol (alcohol)

How are alcoholic beverages produced, consumed and abused

66



What are the toxicological properties of alcohol (ethanol)

What is BAC and how is it measuredWhat is meant by presumptive and

confirmatory drug testingWhat is meant by the half‐life and drug

clearance time of a drug or poisonWhat is the role of a forensic

toxicologist

77

Chem 113, Prof. J.T. SpencerChem 113, Prof. J.T. Spencer7

ParacelsusParacelsus

“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)

88


www.usdoj.gov/dea/index.htm

www.dea.gov

99


Drugs and ToxinsDrugs and Toxins Drugs - what does the term mean

»Drugs vs. Medicines

Drugs - Natural or synthetic compounds used for physiological (and possibly psychological ) effects.– Medicinal Uses - to correct or help some

physiological or psychological problem– Drug Abuse - chemicals taken for unintended

uses or uncontrolled use (e.g., alcohol addiction).

»Cuts across socio-economic levels»> 75% of forensic investigations involve drug

use»Not victimless crimes.

1010


What is Forensic Toxicology?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)

1111


Drugs and ToxinsDrugs and Toxins

Start with Medicinal Chemistry– Toxins– Poisons– Drug Discovery and Development

• Drug Definitions and Types• Drug Laws• Drug Dependence• Drug Testing and Identification

1212


Drugs and Toxic Drugs and Toxic SubstancesSubstances

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 Sensitization – prior exposure may lead to

heightened reaction Tolerance – adaption of the body to an increase

in exposure Bioaccumulation – compound is not eliminated

– see chronic toxicity

Species LD50

Guinea Pig 0.0006Rabbit 0.115Hamster 3.5Monkey 0.07

1313


Toxic SubstancesToxic Substances

LD50 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

Right to Know LawsRight to Know Laws

1414


MSDS SheetsMSDS 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

1515


MSDS Sheets - ExampleMSDS 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 vapour/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.

1616


Medicinal ChemistryMedicinal Chemistry

Chemicals designed for therapeutic uses. First drugs - “Miracle Drug”

– Long known that willow bark could reduce fever, pain, etc.

– Isolated compound from willow trees. – Acidic form causes side-effects. Chemical

modification could greatly reduce these side effects.

– Toxicity 20-30 g/person with suggested dose - 325 - 750 mg/4hrs.

– Aspirin

1717


Medicinal ChemistryMedicinal Chemistry

1818


Drug Discovery - An AsideDrug Discovery - An Aside Finding new drugs

– Exploring folk remedies (ethnopharmacology)(i.e., aspirin, digitalis, quinine, morphine):

»Researching traditions (shamans and tribal healers).

» Isolating active ingredients and determining their structures ingredients (very difficult chemical investigation).

»Determining if effects are fact or fiction (i.e., aspirin works but rhino horns are without medical validity).

»Synthesis of compounds.»Chemical modification to enhance action (may

be coupled with information from studies on the mode of action of the chemical).

1919


Drug Discovery - An AsideDrug Discovery - An Aside Finding New Drugs

– Fortuitous accidents - the KEY is someone realizing what they have stumbled upon (rare!).

» 1928. Alex. Flemming was curious when he observed that a bacteria culture that had accidentally been contaminated with mold had no bacteria. Series of chance events;

Researcher floor below Flemming studing rare strain of mold (penicillium Notatum).

Flemming working on Staphylococcus (very sensitive to Penicillin)

Mold spores drifted into Flemmings lab and contaminated some of his Petri dishes which were left unwashed while Flemming was on vacation

Uncommonly cool weather slowed bacteria growth but not mold. Then warm weather permitted bacterial growth except around mold

Flemming noticed antibacterial action

2020



– Fortuitous accidents - the KEY is someone realizing what they have stumbled upon (rare!).

2121


Drug Discovery - An AsideDrug Discovery - An Aside

Even when “break” comes from tradition or chance, much very hard scientific work must be done to turn the discovery into something productive.– Penicillin:

» Isolate active agent produced by Penicillium notatum» Separate, purify, concentrate new compound.» Structure and properties of new compound» Efficacy studies (is it really effective) and toxicity» Human studies» Synthesis and production» Expansion to new, related families of compounds -

effective against different strains, allergic effects, etc.» Mode of action (Penicillin kills bacteria by interfering

with the ability to synthesize cell wall.)

2222



– Chemical Modification – modifying side chains to reduce side effects

– Targeted Drug Discovery – use of a planned approach

– Combinatorial Methods – closely related compounds screened for medicinal potential

2323


Often, a drug needs only to have the right functional groups at the right place - - - determine the active portion of a molecule - - - synthesize active portion and manipulate the rest (often simpler than natural product synthesis)

Morphine very difficult to synthesize but Demerol easy (possibly helps improve side effects?)

Targeted Drug DiscoveryTargeted Drug Discovery

Active Area

Morphine Active Area Demerol

2424


Drug Drug Development/ApprovalDevelopment/Approval Drug Development & Approval Process - It costs an est.

average of $800 million (2003) to $1.7 billion (2009) and may take nearly fifteen years to develop one new drug. Only 1 in 1,000 compounds that enter preclinical testing make it to human testing. Only one in five tested in people is approved by the Food & Drug Administration (FDA).

– Synthesis and Extraction– Biological Screening and Pharmacological Testing– Pharmaceutical Dosage Formulation and Stability Testing– Toxicology and Safety Testing– Regulatory Review: Investigational New Drug (IND)

Application– Phase I, II, and III Clinical Evaluations– Process Development for Manufacturing and Quality

Control– Bioavailability Studies– Regulatory Review: New Drug Application (NDA)– Postapproval Research

2525


Poisons (and drugs)Poisons (and drugs)

Intentional or Accidental Poisoning?– Route of entry

» Ingestion» Injection» Inhalation»Absorption across mucous membrane

– Distribution– Elimination

Corrosive Poisons - Substances that actually destroy tissue outright

Metabolic Poisons - Affect biochemical mechanisms

2626


Corrosive PoisonsCorrosive Poisons

Substances that actually destroy tissue outright– Acids/Bases (Alkali)

»Sulfuric Acid (H2SO4)»Hydrochloric Acid (HCl)»Sodium Hydroxide (NaOH; cleaners)

– Death can result from a little as 1 oz. H2SO4

»Works by dehydrating tissues

»Cells die fast because water is removed AND proteins are destroyed by acid-catalyzed hydrolysis of peptide bonds.

2727



Warning Properties:– Corrosive toxins interact with body sensory

systems to alert of exposure:»Ammonia (above 0.01% in air) causes

choking»Acids interact with nerves to send pain

signals upon exposure– Some lack warnings!

»HF (very corrosive; used in electronics) - destroys both tissue / bone but does not cause pain upon tissue exposure . Only sends pain when BONE is exposed.

»Bases (NaOH) slippery

2828



Some are toxic because of reactions– Phosgene (mustard gas, WWI and in plastics

industry) - if inhaled it reacts with water in lungs to form HCl.

»Causes Pulmonary edema (fluid in lungs) because it draws water from surrounding tissues - victim drowns.

»Phosgene does not have good warning properties (smells like new-mown hay and lung reactions are slow.

2929


Metabolic PoisonsMetabolic Poisons Affect Biochemical Mechanisms:

– Carbon Monoxide (Gas) - colorless, odorless, toxic - suicide or homocide.

»Binds to iron in hemoglobin and only very slowly is released - displacing oxygen - Carboxyhemoglobin is 140 time more stable than oxyhemoglobin

»Breathing 0.1% CO in air for 4 hours converts 60% of hemoglobin to carboxyhemoglobin!

»CO produced by incomplete combustion - 200 million tons in US annually

»Not a cumulative poison (given time, the free hemoglobin is released)

3030


Hemoglobin TransportHemoglobin Transport

3131


Arsenic PoisoningArsenic Poisoning

As commonly occurs in pesticides, shrimp, pressure treated wood (Paris green), old wallpaper (green color)

React with SH groups of enzymes - stopping their normal function

Accumulates in the body (not eliminated) Used as a poison gas in WWI - led to search for

antidote and discovery of chelating reagents (molecules that have two or more sites to bind to a single metal center)

3232


Mercury PoisoningMercury Poisoning Fluorescent lamps, dental amalgams, fungicides,

“blocking of hats (“Mad Hatter” syndrome). Newton - alchemy (base metals into gold) -

Newton’s hair had high amounts of mercury. Mechanism:

Active Site Blocked Active Site

Antidote- Chelating Agents

3333


Lead PoisoningLead Poisoning

Romans - Lead Plumbing (downfall of Rome - Pb in Emperor’s wine and water lead to mental illness)

Modern - Leaded Gas, Paint, water pipe joints– Plumbing - (joints) EPA allows max 15 ppb, many

cities have 500 ppb.– Paint - PbO (white paint) - children ingest (now

use TiO2 - not-toxic)– Wine - correlates with sales of leaded gas

Leaded Gas Air Soil Grapes Wine Humans

PicogramsPb/gm wine

Leaded Gas sales in France

1978 1978

3434


CSA, Title II of the Comprehensive Drug Abuse Prevention & Control Act of 1970. – Legal foundation of the

government’s fight against abuse of drugs & other substances.

– A consolidation of numerous laws regulating the manufacture & distribution of narcotics, stimulants, depressants & hallucinogens, steroids

Classifies Drugs into Classes (schedules)

Controlled Substances ActControlled Substances Act

3535


Is there a medicinal value

Does it have potential for abuse

Does it have potential for addiction

Controlled Controlled Substances ActSubstances Act

3636


Schedule ISchedule I

Substance has a high potential for abuse and addiction

Substance has no currently accepted medical use in treatment in the United States

There is a lack of accepted safety for use ofthe substance under medical supervision

Heroin, LSD, Marijuana, Methaqualone

3737


Substance has the highest potential for abuse

Substance has a currently accepted medical use in treatment in the U.S. or a currently accepted medical uses with severe restrictions

Abuse of the substance may lead to severepsychological or physical dependence

Morphine, PCP, cocaine, methadone,methamphetamine

Schedule IISchedule II

3838


Substance has a potential for abuse less than those in Schedules I and II

Has a currently accepted medical use in treatment in the U.S.

Abuse may lead to moderate or low physicaldependence or high psychological dependence

Anabolic steroids, codeine & hydrocodone withaspirin or Tylenol, some barbiturates

Schedule IIISchedule III

3939


The substance has a low potential for abuserelative to those in Schedule III

Has a currently accepted medical use intreatment in the U.S.

Abuse may lead to limited physicaldependence or psychological dependencerelative to those in Schedule III

Librium, Darvon, Xanax, Valium (tranquilizers)

Schedule IVSchedule IV

4040


The substance has low potential for abuse relative those in Schedule IV

Has a currently accepted medical use in treatment in the U.S.

Abuse may lead to limited physical orpsychological dependence relative to thosesubstances in Schedule IV

Over-the-counter cough medicines with codeine

Schedule VSchedule V

4141


AlcoholAlcohol

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.

4242


EthanolEthanol Colorless liquid with a

burning taste and a characteristic odor. 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.

4343


Ethanol DrinksEthanol 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.

4444


Ethanol MetabolismEthanol 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. Physical exercise also delays gastric emptying. Drugs (e.g. nicotine, marijuana, and ginseng), may modify physiological factors regulating gastric emptying.

4545


Ethanol MetabolismEthanol 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.

4646


Ethanol MetabolismEthanol 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).

4747


Alcohol and the BrainAlcohol and the Brain

Parietal LobeParietal Lobe - Discriminate between sensory stimuli, locate and recognize body parts, 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.

4848


Ethanol MetabolismEthanol 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:

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

Practice makes PerfectPractice makes Perfect

What substances are present? What is the unambiguous identity of a

particular chemical? How much of each chemical is present in the

sample? When was the drug taken? Is the compound one normally found in the

body? Was it accidently or intentionally put there?

5050


Specimen CollectionSpecimen Collection

Fluids: Organs:

Blood Skin

Urine Lungs

Vitreous Humuor Hair and Fingernails

Oral Fluid Liver

Semen Kidney

Stomach Contents Bone

Bile Other (heart, brain…)

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.

5151


SamplingSampling

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.

5252


SamplingSampling

Bile - Useful for detection but not concentration.

Kidney - Similar to Bile. Vitreous Humuor - 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.

5353


Additional MatricesAdditional Matrices

Vomit Meconium

Earwax Amniotic Fluid

Semen Umbilical Cord Blood

Feces Milk

Sweat

5454


Specimen Collection: Specimen Collection: Case ExamplesCase 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

5555


Roles of Forensic Roles of Forensic ToxicologyToxicology

Postmortem Forensic Toxicology Human Performance Toxicology Forensic Drug Testing

5656


Specimen CollectionSpecimen 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]

5757


Sample Handling 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).

5858


Postmortem Postmortem Forensic Forensic ToxicologyToxicology 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

5959


Postmortem ToxicologyPostmortem 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.

6060


Postmortem ToxicologyPostmortem 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]

– Not always available.

6161


Postmortem Forensic Postmortem Forensic ToxicologyToxicology

Bile samples

– Alternative if urine unavailable

– Accumulation of drugs

– All available bile should

be collected

– Not an easy sample to analyze

Bile 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.

6262



Liver samples:

Drug metabolism occurs in the liver.

Drugs may be present in higher

concentrations.

Metabolite Analysis

6363



Other specimens:

– Lung (volatiles)

– Spleen (carbon monoxide) – blood

unavailable

– Stomach Contents (drug overdose)

– Hair ( drug use history)

6464


Forensic Drug Testing - Forensic Drug Testing - Where?Where?

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

International Olympic Committee– Athletes

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

Documents

1 Chem 113, Prof. J.T. Spencer Chapter 13 Forensic Chemistry Dr. J. T. Spencer Adjunct T. L. Meeks