what is forensic chemistry - jefferson county public...

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Criminalistics, 10e

Richard Saferstein

© 2011, 2007, 2004, 2001, 1998, 1995 Pearson Higher Education,

Upper Saddle River, NJ 07458. • All Rights Reserved.

Forensic Chemistry

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What is Forensic Chemistry

• Applied analytical chemistry

• Qualitative analysis

– Identify material – what is it

– Must be done before quantitative

• Quantitative analysis

– Percentage of components in a mixture

• Comparative analysis

– Identification

– Classification

– individualization

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Areas of Forensic Chemistry

• Chromotography

• Microscopy

• Drug analysis/Toxicology

• Chemical analysis of physical evidence

– Arson/explosives/ GSR

– Inks/paints/dyes

– Fibers/ paper/plastic/ adhesives

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Chromatography

• Technique where mixtures are separated into

components by attraction to a stationary phase while

being propelled by a moving phase

– Thin layer (TLC)

– Gas liquid (GLC or GC)

– High pressure liquid (HPLC)

• Used to identify

– Inks

– Drugs

– Accelerants

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Microscopy

• Fibers/hair

• Soil

• Glass

• Drug crystals

• Inks

• Paints

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Drug Analysis

• Presumptive tests

• Color tests

• Crystal tests using microscopy

• TLC

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Chapter 9

DRUGS

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Introduction• A drug can be defined as a natural or synthetic

substance that is used to produce physiological or psychological effects in humans or other higher order animals.

• Narcotic drugs are analgesics, meaning they relieve pain by a depressing action on the central nervous system. This effects functions such as blood pressure, pulse rate, and breathing rate.

• The regular use of a narcotic drug will invariably lead to physical dependence.

• The most common source for these narcotic drugs is opium, extracted from poppies.

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Controlled Substances Act

• Government maintains 5 schedules of classifications for controlled substances

• Based on

– Potential for abuse

– Potential for dependence

– Medical value

• US Attorney General has authority to add, delete, or reschedule a drug as more info becomes available

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Abuse

• Inappropriate use

• Unwarranted use

• Over use

• May or may not be

addictive

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Dependence

• Physical dependence occurs when

the drug becomes necessary for

their body to function normally

• Psychological dependence occurs

when a person thinks they need a

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Schedule I• High potential for abuse

• No currently accepted medical use

• Lacks accepted safety of use in

treatment under medical supervision

Heroin Marijuana

PCP LSD

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Schedule II• High potential for abuse

• Has an accepted medical use or a medical

use w/severe restrictions

• Potential for severe psychological/physical

dependence

Cocaine opium methodone

PCP Dronabinol

Most amphetamine & barbiturate derivatives

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Schedule III• Less potential for abuse than I & II

• Current accepted medical use in US

• low/moderate physical dependence or high

psychological dependence

Anabolic steroids

all barbiturate preparations (except

phenobarbitol) not covered in II

Certain codeine preparations

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Schedule IV– Lower potential for abuse than schedule III

– Valid medical use in US

– Abuse may lead to limited dependence

relative to III

Darvon Phenobarbital

Valium Librium

tranquilizers

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Schedule V• Low abuse potential

• Valid medical use in US

• Lower potential for producing dependence than

schedule IV

Robitussin

Low dose codeine preps.

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Types of Drugs

• Narcotics

• Hallucinogens

• Depressants

• stimulants

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Narcotics-induce a state of

lethargy or sluggishness

• Narcotics a analgesics –relieve pain

• Most come from the poppy plant

• Example Narcotics

Morphine Methadone

Heroin Codeine

OxyContin

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Opiates• Type of narcotic

• Morphine is readily extracted from opium and is

used to synthesize heroin.

• Addicts frequently dissolve heroin in water by

heating it in a spoon, and then inject in the skin.

• Heroin produces a “high” that is accompanied by

drowsiness and a sense of well-being that

generally last for three to four hours.

• Codeine is also present in opium, but it is usually

prepared synthetically from morphine.

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Other Opiates• OxyContin, with the active ingredient oxycodone,

is not derived from opium or morphine, but does have the same physiological effects on the body as do opium narcotics.

• OxyContin is prescribed to a million patients for treatment of chronic pain.

• Methadone is another well-known synthetic opiate.

• Methadone which is pharmacologically related to heroin, appears to eliminate the addict’s desire for heroin while producing minimal side effects.

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Hallucinogens

• Another class of drugs is hallucinogens; marijuana is the most well-known member of this class.

• Hallucinogens cause marked changes in normal thought processes, perceptions, and moods.

• Marijuana is the most controversial drug in this class because its long-term effects on health are still largely unknown.

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Marijuana• Marijuana is the most controversial drug in this class

because its long-term effects on health are still largely unknown.

• Marijuana refers to a preparation derived from the plant Cannabis.

• The chemical substance largely responsible for the hallucinogenic properties of marijuana is known as tetrahydrocannabinol, or THC.

• The THC content of Cannabis varies in different parts of the plant, generally decreasing in the following sequence: resin, flowers, leaves, with little THC in the stem, roots, or seeds.

• The THC-rich resin is known as hashish.

• Marijuana does not cause physical dependency, but the risk of harm is in heavy, long-term use.

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Other Hallucinogens• Other hallucinogens include LSD, mescaline, PCP,

psilocybin, and MDMA (Ecstasy).

• LSD is synthesized from lysergic acid, and can cause

hallucinations that can last for 12 hours.

• Phencyclidine, or PCP, is often synthesized in clandestine

laboratories and is often smoked, ingested, or sniffed.

• Phencyclidine is often mixed with other drugs, such as

LSD, or amphetamine, and is sold as a powder (“angle

dust”), capsule, or tablet.

• Oral intake of PCP first leads to feelings of strength and

invulnerability, which may turn to depression, tendencies

toward violence, and suicide.

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Depressants• Depressants are another class of drugs.

• Depressants are substances used to depress the functions of the central nervous system.

• Depressants calm irritability and anxiety and may induce sleep.

• These include alcohol (ethanol), barbiturates, tranquilizers, and various substances that can be sniffed, such as airplane glue, model cement, or aerosol gas propellants such as freon.

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Depressants• Alcohol (ethyl alcohol) enters the body’s

bloodstream and quickly travels to the brain, where it acts to suppress the brain’s control of thought processes and muscle coordination.

• Barbiturates, or “downers,” are normally taken orally and create a feeling of well-being, relax the body, and produce sleep.

• Tranquilizers, unlike barbiturates, produce a relaxing tranquility without impairment of high-thinking faculties or inducing sleep.

• Sniffing has immediate effects such as exhilaration, but impairs judgment and may cause liver, heart, and brain damage or even death.

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Stimulants

• Stimulate (speed up) action in central

nervous system

• The drug classification of stimulants includes

amphetamines, sometimes known as

“uppers” or “speed,” and cocaine, which in

its free-base form is known as crack.

• Stimulants are substances taken to increase

alertness or activity, followed by a decrease

in fatigue and a loss of appetite.

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Stimulants• Amphetamine and methamphetamine, often

injected intravenously, cause an initial “rush,” followed by an intense feeling of pleasure.

• This is followed by a period of exhaustion and a prolonged period of depression.

• Cocaine, extracted from the leaves of Erythroxylincoca, causes increased alertness and vigor, accompanied by the suppression of hunger, fatigue, and boredom.

• Crack is cocaine mixed with baking soda and water, then heated.

• Crack is often smoked in glass pipes, and, like cocaine, stimulates the brain’s pleasure center.

• Crystal Meth27

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Club Drugs

• The term club drugs refers to synthetic drugs that are used at nightclubs, bars, and raves (all-night dance parties).

• Substances that are often used as club drugs include, but are not limited to, MDMA (Ecstasy), GHB (gamma hydroxybutyrate), Rohypnol (“Roofies”), ketamine, and methamphetamine.

• GHB and Rohypnol are central nervous system depressants that are often connected with drug-facilitated sexual assault, rape, and robbery.

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Club Drugs

• Methylenedioxymethamphetamine, also known as MDMA or Ecstasy, is a synthetic mind-altering drug that exhibits many hallucinogenic and amphetamine-like effects.

• Ecstasy enhances self-awareness and decreases inhibitions; however, seizures, muscle breakdown, stroke, kidney failure, and cardiovascular system failure often accompany chronic abuse.

• Ketamine is primarily used as a veterinary animal anesthetic that in humans causes euphoria and hallucinations.

• Ketamine can also cause impaired motor functions, high blood pressure, amnesia, and mild respiratory depression.

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Anabolic Steroids

• Yet another category of drugs is the anabolic steroids.

• These are synthetic compounds that are chemically related to the male sex hormone testosterone.

• Anabolic steroids are often abused by individuals who are interested in accelerating muscle growth.

• Side effects include unpredictable effects on mood and personality, depression, diminished sex drive, halting bone growth, and liver cancer.

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Drug Identification• The challenge or difficulty of forensic drug

identification comes in selecting analytical procedures that will ensure a specific identification of a drug.

• This plan, or scheme of analysis, is divided into two phases.

– Screening test that is nonspecific and preliminary in nature to reduce the possibilities to a manageable number.

– Confirmation test that is a single test that specifically identifies a substance.

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Preliminary Analysis

• Faced with the prospect that the unknown substance may be any one of a thousand or more commonly encountered drugs, the analyst must employ screening tests to reduce these possibilities to a small and manageable number.

• This objective is often accomplished by subjecting the material to a series of color tests that will produce characteristic colors for the more commonly encountered illicit drugs.

• Microcrystalline tests can also be used to identify specific drug substances by studying the size and shape of crystals formed when the drug is mixed with specific reagents.

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Color Tests• Marquis

– Turns purple in presence of heroin, morphine, &

most opium derivatives

– Orange-brown when mixed w/amphetamines &

metamphetamines

• Dillie-Koppanyl

– Turns violet-blue in presence of bartiturates

• Duquenois-Levine

– Purple top layer is positive test for marijuana

• Van Urk

– Blue-purple in presence of LSD

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Color Tests

• Scott Test

– 3 part test

– Cocaine turns solution A blue

– Blue changes to pink when solution B is added

– Blue reappears in chloroform layer when solution

C is added

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Microcrystalline Tests

• More specific than color tests

• Drop of chemical reagent added to small

quantity of drug on microscope slide

• Chemical reaction occurs producing crystalline

precipitate

• Looking at size & shape of crystals

• Are highly characteristic of the drug

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Confirmational Determination

• Once this preliminary analysis is completed, a confirmational determination is pursued.

• Forensic chemists will employ a specific test to identify a drug substance to the exclusion of all other known chemical substances.

• Typically infrared spectrophotometry or mass spectrometry is used to specifically identify a drug substance. Sometimes chromatography can also be used

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Chromatography

• Separates drugs from their dilutants

• Chemist must first have an idea of what the

drug is

• Often performed along with color & crystal

tests

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Spectrophotometry

• Selective absorption of light by drugs in UV or

IR

• UV is not conclusive for a positive ID of a drug

because other materials may very well

produce an indistinguishable spectrum

• IR can specifically identify a substance

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Mass Spectrometry

• Readily separates a drug from other

substances that may be present in the drug

preparation

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Collection and Preservation

• The field investigator has the responsibility of ensuring that the evidence is properly packaged and labeled for the laboratory.

• Generally common sense is the best guide, keeping in mind that the package must prevent the loss of the contents and/or cross-contamination.

• Often the original container in which the drug was seized will suffice.

• Specimens suspected of containing volatile solvents (glue-sniffing) must be packaged in airtight containers to prevent evaporation of solvent

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• All packages must be marked with

information that is sufficient to ensure

identification by the officer in the future and

establish the chain of custody.

• Any field test results should be forwarded to

lab

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Chapter 10

FORENSIC TOXICOLOGY

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Introduction• Toxicologists are charged with the responsibility

for detecting and identifying the presence of drugs and poisons in body fluids, tissues, and organs.

• Toxicologists not only work in crime laboratories and medical examiners’ offices, but may also reach into hospital laboratories and health facilities to identify a drug overdose or monitor the intake of drugs.

• A major branch of forensic toxicology deals with the measurement of alcohol in the body for matters that pertain to violations of criminal law.

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Some Bodily

Evidence of Drug Use

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Repeated injections may develop permanent slits in the skin


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Skin Rash-common skin condition for addicts who

shoot up

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The bottom of the brain

These black spots on the brain indicate long-term

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A cross section of the Brain

Hemorrhage caused by a cocaine overdose

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Upper Saddle River, NJ 07458. • All Rights Reserved.Hemorrhage caused by a cocaine overdose

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Drug Smuggling

One common way to smuggle drugs into

the country is to swallow a plastic bag

filled with cocaine, heroin, or some

other illegal contraband. After passing

through customs, the smuggler will the

“throw up” the bag. This plan goes

south if the bags burst while in the

stomach.

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The black spots in this stomach indicate where bags of

cocaine burst, causing a massive over dose.


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Toxicology of Alcohol• The analysis of alcohol exemplifies the primary

objective of forensic toxicology—the detection and isolation of drugs in the body for the purpose of determining their influence on human behavior.

• Alcohol, or ethyl alcohol, is a colorless liquid normally diluted with water and consumed as a beverage.

• Like any depressant, alcohol principally effects the central nervous system, particularly the brain.

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Alcohol Levels• Alcohol appears in the blood within minutes after it has

been taken by mouth and slowly increases in concentration while it is being absorbed from the stomach and the small intestine into the bloodstream.

• When all the alcohol has been absorbed, a maximum alcohol level is reached in the blood; and the postabsorption period begins.

• Then the alcohol concentration slowly decreases until a zero level is again reached.

• Factors such as time taken to consume the drink, the alcohol content, the amount consumed, and food present in the stomach determine the rate at which alcohol is absorbed.

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Alcohol Levels

• Elimination of alcohol throughout the body is accomplished through oxidation and excretion.

• Oxidation takes place almost entirely in the liver, while alcohol is excreted unchanged in the breath, urine, and perspiration.

• The extent to which an individual may be under the influence of alcohol is usually determined by either measuring the quantity of alcohol present in the blood system or by measuring the alcohol content in the breath.

• Experimental evidence has verified that the amount of alcohol exhaled in the breath is in direct proportion to the blood concentration.

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Alcohol and Circulatory System• Humans have a closed circulatory system consisting of

a heart, arteries, veins, and capillaries.

• Alcohol is absorbed from the stomach and small intestines into the blood stream.

• Alcohol is carried to the liver where the process of its destruction starts.

• Blood, carrying alcohol, moves to the heart and is pumped to the lungs.

• In the lungs, carbon dioxide and alcohol leave the blood and oxygen enters the blood in the air sacs known as alveoli.

• Then the carbon dioxide and alcohol are exhaled during breathing.

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Breath Testers

• Breath testers that operate on the principle of infrared light absorption are becoming increasingly popular within the law enforcement community.

• Many types of breath testers are designed to capture a set volume of breath.

• The captured breath is exposed to infrared light.

• It’s the degree of the interaction of the light with alcohol in the captured breath sample that allows the instrument to measure a blood alcohol concentration in breath.

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Field Testing• Law enforcement officers typically use field

sobriety tests to estimate a motorist’s degree of

physical impairment by alcohol and whether or

not an evidential test for alcohol is justified.

• The horizontal gaze nystagmus test, walk and

turn, and the one-leg stand are all considered

reliable and effective psychophysical tests.

• A portable, handheld, roadside breath tester may

be used to determine a preliminary breath-

alcohol content.

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Gas Chromatography Testing• Gas chromatography offers the toxicologist the

most widely used approach for determining alcohol levels in blood.

• Blood must always be drawn under medically accepted conditions by a qualified individual.

• It is important that a nonalcoholic disinfectant be applied before the suspect’s skin is penetrated with a sterile needle or lancet.

• Once blood is removed from an individual, its preservation is best ensured when it is sealed in an airtight container after an anticoagulant and a preservative have been added and stored in a refrigerator.

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Alcohol and Law• The American Medical Association and the

National Safety Council have been able to exert considerable influence in convincing the states to establish uniform and reasonable blood-alcohol standards.

• Between 1939 and 1964 a person having a blood-alcohol level in excess of 0.15 percent w/v was to be considered under the influence, which was lowered to 0.10 percent by 1965.

• In 1972 the impairment level was recommended to be lowered again to 0.08 percent w/v.

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Alcohol and Law• Starting in 2003, states that have not adopted the

0.08 percent per se level will lose part of their federal funds for highway construction.

• To prevent a person’s refusal to take a test for alcohol consumption, the National Highway Traffic Safety Administration recommended an “implied consent” law.

• Adopted by all states by 1973, this law states that the operation of a motor vehicle on a public highway automatically carries with it the stipulation that a driver will submit for a test for alcohol intoxication if requested or be subject to loss of the license.

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Role of the Toxicologist• Beyond the analysis of alcohol, the toxicologist is

confronted with a maze of drugs and poisons.

• The toxicologist is originally presented with body fluids and/or organs and is normally requested to examine them for the presence of drugs and poisons.

• Without supportive evidence, such as the victim’s symptoms, a postmortem pathological examination, or an examination of the victim’s personal effects, the toxicologist is forced to use general screening procedures with the hope of narrowing thousands of possibilities to one.

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Role of the Toxicologist• In addition, the toxicologist is not dealing with

drugs at the concentration levels found in powders and pills, having been dissipated and distributed throughout the body.

• Furthermore, the body is an active chemistry laboratory as few substances enter and completely leave the body in the same chemical state.

• Last, when and if the toxicologist has surmounted all of these obstacles, he or she must be prepared to assess the toxicity of the drug or poison.

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The Analytical Scheme• The forensic toxicologist must devise an analytical

scheme that will successfully detect, isolate, and specifically identify toxic drug substances.

• Once the drug has been extracted from appropriate biological fluids, tissues, and organs, the forensic toxicologist can proceed to identify the drug substance present.

• Drug extraction is generally based on a large number of drugs being either acidic or basic.

• The strategy used for identifying abused drugs entails a two-step approach: screening and confirmation.

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The Screening Step

• A screening test is normally employed to provide the

analyst with quick insight into the likelihood that a

specimen contains a drug substance.

• Positive results arising from a screening test are

considered to be tentative at best and must be

verified with a confirmation test.

• The most widely used screening tests are thin-layer

chromatography, gas chromatography, and

immunoassay.

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The Confirmation Step• Gas chromatography/mass spectrometry is

generally accepted as the confirmation test of

choice.

• The GC separates the sample into its components,

while the MS represents a unique “fingerprint”

pattern that can be used for identification.

• Once the drug is extracted and identified, the

toxicologist may be required to provide an

opinion on the drug’s effect on an individual’s

natural performance or physical state.

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The DRE• The Drug Recognition Expert program

incorporates standardized methods for examining automobile drivers who are suspected of being under the influence of drugs.

• To ensure that each subject has been tested in a routine fashion, each DRE must complete a standard Drug Influence Evaluation form.

• The DRE program usually cannot determine which specific drug was ingested.

• Hence, it is the production of reliable data from both the DRE and the forensic toxicologist that is required to prove drug intoxication.

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Thin Layer Chromatography


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Preparing a Sample Space

• Cut a sheet of paper so it may

hang free within the intended

container

• Mark a sample line ½ inch to an

inch from the bottom

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Place your

samples on

the sheets


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Starting the Sample

• Place the sheet in a container

with a solvent

• The bottom of the paper should

be submerged into the solvent,

but not above the samples

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Allow your

samples to run

at least ½ way

up the sample

space


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Upper Saddle River, NJ 07458. • All Rights Reserved.bsapp.combsapp.com

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Allow your samples to dry


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Matching Samples

• Note component colors

• Calculate Rf values

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Calculating Rf Values

� Rf value is a ratio of distance a

component sample moves to the

distance the solvent moves

� This number is usually expressed

as a decimal


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Calculating Rf

Values

� Starting point

� 8 cm

� 4 cm

� Solvent finish 10 cm

Rf = 4/10

= 0.4

Rf = 8/10

= 0.8

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