Test 2 Flashcards
Physical properties describe?
A substance without reference to any other substance
A chemical property describes?
the behaviour of a substance when it reacts or combines with another substance
An element is
the simplest substance that provides the building block from which all matter is composed
Matter is
Anything that has a mass and occupies space
Matter can be classified according to
Solid-definite shape and volume
Liquid-specific volume shape of container
Gas/vapor neither definite shape nor volume
Temperature is a measure of
Heat intensity or hotness or coldness of a substance
What is the most commonly used temperature scale
Celsius scale
The celsius scale is derived by assigning the freezing point of water of a value of ___ degrees and a boiling point of a value of ____ degrees
0
100
Mass refers to
The amount of matter an object contains independent of gravity
The mass of an object is determined by
Comparison to the known mass of standard objects
Density is defined as
pass per unit volume (D= M/V)
Density remains __________ regardless of sample size
The same
What is considered a characteristic property of a substance and can be used as an aid in identification
Density
What causes light waves to bend?
After traveling at a constant velocity it travels until they penetrate and slow into another medium such as glass or water
The bending of light waves because of a change in velocity is called
Refraction
Light is refracted when it
Travels obliquely from one medium to another
Density and Refraction are _________ and will serve to characterize a ____________
intensive properties
substance
Crystalline solids have definite geometric forms because
of the orderly arrangement of their atoms
Crystalline solids refract a beam of light in 2 different light-ray components which results in
Double refraction
Birefringence is
the numerical difference between crystalline double refraction
Are all solids crystalline in nature?
No, glass has a random arrangement of atoms to form an amorphous or noncrystalline solid
What two models describe the behaviour of light
- Light is described as a continuous wave
- Light is depicted as a stream of discrete energy particles
Waves are described in terms such as
Wavelength
Frequency
What is Wavelength
the distance between two successive crests (or one trough to next trough)
What is Frequency
the number of crests (or troughs) passing any one given point per unit of time
Frequency and Wavelength are _______________ to each other
inversely proportional
Longer toughs means the frequency is _________
Shorter waves means the frequency is __________
Lower
Higher
Coherent Radiation
The photons oscillate at the same frequency
Incoherent Radiation
The photons oscillate at different frequencies.
Glass is composed of
Silicon oxides (sand) mixed with various metal oxides
What is added to sand to lower its melting point
Sodium carbonate (soda)
What is added to sand to prevent glass from dissolving in water
Calcium carbonate (lime)
What is it called when molten glass is cooled in a bath of molten tin
Float glass
Tempered glass is stronger than normal glass due to
the rapid heating and cooling of the glass surfaces
Laminated glass has
A layer of plastic between two pieces of ordinary window glass
What is the problem of glass comparison in forensic science
The need to find and measure those properties that will associate one glass fragment with another
What two physical properties when comparing glass fragments must a forensic scientist evaluate
- Densities
- Refractive index
What is the floatation method?
Precise and rapid method for comparing glass densities
What occurs during the floatation method
- A glass particle is immersed in a liquid
- The density of the liquid is adjusted by the addition of small amounts of an appropriate liquid until the glass chip remains suspended in the liquid
- The glass will have the same density as the liquid medium and can be compared to other relevant pieces of glass which will remain suspended, sink, or float
What is the Glass immersion method?
Used to determine a glass fragments refractive index
What occurs during the Glass Immersion Method
Immersing a glass particle in a liquid medium whose refractive index is varied until it is equal to that of the glass particle
What is The Becke line
A bright halo near the border of a particle that is immersed in a liquid of a different refractive index
What is the match point?
When the Becke line disappears and minimum contrast between liquid and particle is observed
Radical fractures
Crack that radiates outward
Concentric fractures
Fractures forming in a circular pattern around the point of impact
What is the 3R Rule when analyzing cracks
Radial cracks form a Right angle on the Reverse side of the force
Glass fragments should be packaged in
Solid containers
A drug can be defined as
A natural or synthetic substance that is used to produce physiological or psychological effects in humans
Psychological dependence
Stems from conditioned use of a drug caused by emotional needs
Physical dependence
is a physiological need for a drug brought about by regular use and characterized by withdrawal sickness when the drugs stop
What two drugs whose regular use do not lead to physical dependence?
Marijuana and cocaine
What are analgesics
Relieve pain by a depressing action on the central nervous system
What do analgesics or Narcotics affect
Blood pressure, pulse rate and breathing rate
Morphine
extracted from opium and is used to synthesize heroin
Heroin
High that causes drowsiness and a sense of well-being that generally last 3-4 hours
Codeine
Present in opium but its usually prepared synthetically from morphine
Oxycontin
Is not derived from opium or morphine but does have the same physiological effects on the body as opium narcotics
Methadone
Is a synthetic opiate and related to heroin
Eliminates addicts desire for heroin while producing minimal side effects
What is the difference between codeine/heroin to morphine
Codeine and heroin have less analgesic and sedative effects
Hallucinogens
Cause changes in normal thought processes, perceptions, and moods
THC-rich resin is known as
Hashish
THC concentration ranges from
8-14%
Hashish oil ranges from
15-50%
LSD
Derived from a fungus, ergot
How potent is LSD
Highly potent
.25 milligrams is enough to cause hallucinations
Synesthesia
sound appearing as hallucinatory visions
Phencyclidine (PCP)
Is a hallucinogen and mixed with other drugs and sold as powder, capsule, or tablet
What are the effects of PCP
First feelings of strength and invulnerability which turn into depression, tendencies toward violence, and suicide
Depressants
Depress the functions of the central nervous system
Calm irritability and anxiety and may induce sleep
Barbiturates
“Downers”
Taken orally and create feeling of well-being, relax body and produce sleep
Tranquilizers
produce a relaxing tranquility without impairment of high-thinking faculties or inducing sleep
Stimulants
injected intravenously, cause initial rush, followed by pleasure then prolonged feeling of depression
Who was the pioneering psychologist (famous) who created quite a sensation in European medical circles by describing his experiments
Wilhelm Wundt
Crack
Is cocaine mixed with baking soda and water then heated
What is created when cocaine and heroin are combined
Speedball
Is Cocaine water soluble?
It is an ionic salt and IS water soluble
Is Crack Cocaine water soluble?
Is a neutral molecule that is insoluble in water
How is cocaine made?
Cocaine is an amine (base-B) that is extracted from crushed leaves of a coca plant by treating with hydrochloric acid (HCI)
What are the steps in producing various forms of cocaine from raw coca plant?
- Soak coca leaves in solvents to extract cocaine.
- Crush leaves, add alcohol to remove impurities.
- Wash and treat with kerosene to yield coca paste (60% pure).
- Coca paste isn’t water-soluble, so it’s not injectable.
- Treat with acid to make water-soluble hydrochloride salt.
- Treat with baking soda to get freebase or crack cocaine.
How do Neurotransmitters work as Chemical Messengers
- Picking an impulse, a nerve cell releases neurotransmitters into the synaptic area
- Neurotransmitters migrate to a second nerve cell and bind to receptor sites
- Receptor site binding results in the production of a signal in the second cell
- Neurotransmitters are released from receptor sites and can travel back to the original cell
What is Half-life
Is the amount of time required for one half of a substance to react
What is half-life in pharamceuticals
How long it takes for one half of the drug to be eliminated from the body
What is the half-life of caffeine
4 hours
What is the half-life of nicotine
2.5 hours
What is the half-life of cocaine before it is metabolized
45 minutes
What is the half-life of THC?
19 hours
total clearance of THV involves 2 weeks
What is the half-life of LSD
3 hours
What are the effects of Ecstasy
Enhances self-awareness and decreases inhibitions
What are the effects of Ecstasy when abused
seizures, muscle breakdown, stroke, kidney failure, and cardiovascular system failure
What are the effects of Ketamine?
Causes euphoria and hallucinations
Can also cause impaired motor functions, high blood pressure, amnesia, and mild respiratory depression
Anabolic Steroids
Synthetic compounds that are chemically related to the male sex hormone testosterone
What does the the Controlled Substance Act illustrate
A legal drug-classification system created to prevent and control drug abuse
The Controlled Substance Act establishes 5 schedules of classification for controlled dangerous substances on the basis of a drugs:
Potential for abuse
Potential for physical and psychological dependence
Medical value
What is Schedule 1 of drug Classification
Schedule 1 drugs have a high potential for abuse and have no currently accepted medical use such as heroin, marijuana, methaqualone, and LSD
What is Schedule 2 of drug Classification
Schedule 2 drugs have a high potential for abuse and have medical use with a severe restriction such as cocaine, PCP, and most amphetamine and barbiturate prescriptions. Dronabinol, the synthetic equivalent of the active ingredient in marijuana is placed in Schedule 2 by virtue of its use in treating glaucoma and chemotherapy patients
What is Schedule 3 of drug Classification
Schedule 3 drugs have less potential for abuse and a currently accepted medical use such as all barbiturate prescriptions not covered under Schedule 2, such as codeine and anabolic steroids
What is Schedule 4 of drug Classification
Schedule 4 drugs have a low potential for abuse and have current medical use such as Darvon, phenobarbital, and some tranquilizers such as diazepam (Valium) and chlordiazepoxide (Librium)
What is Schedule 5 of drug Classification
Schedule 5 drugs must show low abuse potential and have medical use such as opiate drug mixtures that contain non-narcotic medicinal ingredients
What are the two phases in analyzing drugs
- Screening test: that is non-specific and preliminary in nature to reduce the possibilities to a manageable number
- Confirmation test: that is a single test that specifically identifies a substance
Maruis test
Used for opium derivatives
What are the colors for the Maruis Drug Test?
Purple: heroin and opium
Orange brown: amphetamines
Dillie Koppanyi test
Barbituates turn blue
Duquenois Levine
Marijuana turn purple
Scott test
Cocaine turns blue
HCI turns colorless or light pink
Chloroform blue colour reappears
Van Urk
LSD turns blue purple
Preliminary Analysis: Mircocrystalline test
Identify specific drugs by studying the size and shape of crystals formed when the drug is mixed with specific reagents
Conformational Determination
Once the preliminary analysis is completed this is pursued to identify a drug substance and exclude all other substances
What are typically used to specifically identify a drug substance
infrared spectrophotometry or gas chromatography-mass spectrometry
What is the basic principle behind chromatography?
Chromatography relies on the tendency of chemical substances to escape into their surroundings when dissolved in a liquid or adsorbed on a solid
How do molecules reach equilibrium between liquid and gas phases?
When a liquid is covered, molecules escape into the air above, accumulate, and eventually reach equilibrium.
How does equilibrium occur
Equilibrium occurs when the rate of molecules leaving the liquid equals the rate returning.
How does chromatography help in separating mixtures?
Chromatography separates and identifies components of a mixture based on their distribution between the moving and stationary phases
What are some common uses of chromatography?
Chromatography is vital for biochemists to separate mixtures, analyze flavors, scents, pollutants, and detect drug traces.
Forensic scientists use it to analyze evidence, and food scientists check if color additives comply with legal standards.
TLC- Thin Layer Chromatography
uses a solid stationary phase usually coated onto a glass plate and a mobile liquid phase to separate the components of the mixture
TLC is a rapid, qualitative analytical method
What are the properties of the absorbent and solvent used for in TLC?
Pull the components up the plate
What happens when the liquid gets pulled up the plate
It will slowly rise up the plate by capillary action causing the sample to become distributed between the stationary phase and the moving liquid phase
Since most compounds are colourless how do we see the materials?
Placing plates under ultraviolet light or spraying the plate with a chemical reagent
The distance a spot travels up a thin-layer plate is known as?
the R value
Fluorescence
Emission of light by a substance that has absorbed light or other electromagnetic radiation
Is a form of luminescence
Gas Chromatography flow column
- Sample introduced via syringe into injection port
- A stream of nitrogen gas flows through injector carrying sample into column
- Here we have a thin film of liquid
- Here sample is separated in column and carrier gas and separated components emerge from column and enter detector
- Signals developed by detector activate recorder
- The recorder produces a trace of separation with elution time and peak area gives concentration
What is the written record of the GC separation called?
Chromatogram
What is the time required for a component to emerge from a GC column known as
Retention time
What is the unique feature of mass spectrometry?
Under carefully controlled conditions, not two substances produce the same fragmentation pattern
In mass spectrometer a beam of high energy electrons collide with material producing
Positively charged ions
What is Mass Spectrometry
a tool useful for measuring the mass-to-charge ratio of one or more molecules present in a sample
What is the connection between Gas Chromatography column and the mass spectrometer
Allows each component to flow into the mass spectrometer as it emerges from the GC
Spectrophotometry
Measures the quality of radiation that a particular material absorbs as a function of wavelength and frequency
Beers Law
a more concentrated solution absorbs more light than a more dilute solution does.
Currently, what do most forensic laboratories use to characterize chemical compounds
UV and IR spectrophotometers
Between the UV and IR spectrum what gives the best result?
IR spectrum provides a far more complex pattern
Spectrophotometer
The instrument used to measure and record the absorption spectrum of a chemical substance
What are the components of spectrophotometer
A radiation source
A monochromator or frequency selector
A sample holder
A detector to convert electromagnetic radiation into an electrical signal
A recorder to produce a record of the signal
Where can Absorption spectra be done
in visible, ultraviolet (UV) or infrared (IR) regions
Forensic toxicologists
responsibility for detecting and identifying the presence of drugs and poisons in body fluids, tissues, and organs
Where does alcohol affect?
The central nervous system, the brain
What is alcohols fate in the human body
Absorption
Distribution
Elimination
How quickly does alcohol enter the bloodstream?
Alcohol appears in the blood within minutes after drinking.
What happens as alcohol absorbs?
BAC increases until all alcohol is absorbed, then starts to decrease.
How long does absorption take?
On an empty stomach, it takes 30-90 minutes; with a full stomach, 2-4 hours.
Does the type of drink matter?
Yes, drinks like beer absorb more slowly due to carbohydrates, leading to a lower peak BAC.
Where does alcohol go after absorption?
It spreads evenly across watery parts of the body, making up about two-thirds of body volume.
What if blood isn’t available for BAC testing?
Other body fluids like brain tissue, cerebrospinal fluid, or vitreous humor can be used to estimate BAC.
How does the body eliminate alcohol?
Mainly through oxidation in the liver, where enzymes break alcohol into carbon dioxide and water.
Is all alcohol oxidized?
No, about 5% is excreted unchanged in breath, urine, and sweat.
What is BAC?
BAC is measured as percent weight per volume; for instance, 0.10% BAC is 0.10 grams per 100 milliliters of blood.
How fast does BAC decrease?
he average rate is 0.015% per hour; at 0.10% BAC, it takes about 6.5 hours to return to zero.
What is BAC? How is it measured?
BAC indicates alcohol level in blood, detectable by blood or breath.
What is the legal BAC limit for driving?
The U.S. legal limit is 0.08%.
How does alcohol enter the bloodstream?
Alcohol absorbs from the stomach/intestines.
How does alcohol circulate in the body?
It travels via the blood, processed by the liver, then reaches the lungs for exchange with breath.
How do breath testers work?
They measure BAC by infrared absorption or fuel cells.
Why is breath temperature important?
At 34°C, the blood-to-breath alcohol ratio (2,100:1) enables BAC estimation.
What is a field sobriety test?
Officers assess physical impairment.
Are roadside breath testers reliable in court?
Portable testers provide preliminary results but aren’t admissible as proof.
How do labs analyze blood alcohol?
Forensics use gas chromatography; clinical labs use auto-analyzers.
What chemical reactions are involved in testing BAC?
Alcohol is converted by enzymes for analysis.
How is blood collected and preserved?
Blood is taken under medical conditions, with anticoagulants, and stored properly.
Why is proper preservation necessary?
Incorrect storage can alter BAC, especially in deceased samples.
What laws regulate BAC for drivers?
A BAC over 0.08% is legally intoxicated.
What is “implied consent”?
Drivers must agree to testing or risk license suspension.
What does a toxicologist analyze?
Toxicologists examine fluids for drugs or poisons.
What challenges do toxicologist face?
They work with complex substances, often altered within the body.
How is drug detection conducted?
Screening
Confirmation
What’s the first step of the Analytical Scheme?
Screening, a preliminary test for potential drug presence
Whats the second step of the Analytical Scheme?
The confirmation test has chromatography/mass spectrometry (GC/MS) is generally accepted as the confirmation test of choice
What are the most widely used screening tests?
TLC and GC
In the Confirmation Step what do the GC and MS do?
The GC separates the sample into its components, while the MS represents a unique “fingerprint” pattern that can be used for identification
What do toxicologists evaluate?
Drug effects on behavior and physical state
What factors influence interpretation?
Dosage, tolerance, and personal health
How does hair analysis track drug use?
Drugs present in blood diffuse through the capillary walls into the base of the hair and become permanently entrapped in the hairs hardening protein structure
Can hair reveal a timeline?
As the hair continues to grow, the drugs location on the hair shaft becomes a historical marker for delineating drug intake
How are poisons like metals detected?
Heavy metals are detected by copper strip tests.
How is carbon monoxide measured?
Spectrophotometry or gas chromatography measures its blood concentration.
