Forensic Toxicology - Exam 4

breath alcohol testing

the analysis of a person’s breath to determine the presence of and the amount (concentration) of ethanol in the sample

evidential

desk top device usually at the police department or county jail

non-evidential

preliminary breath tester, ignition interlock device

objective, easy, fast, non-invasive, available, no chain-of-custody

advantages of breath testing

alveoli

termination point of the respiratory tract

2100:1

advocated BBR (Blood:Breath Ratio)

underestimate

taking 2300:1 as the real BBR in humans predicts that using breath will __________ BAC by 9%

increase temperature, increase evaporation

effects to increase BrAC

decrease temperature, decrease evaporation

effects to decrease BrAC

1 degree change in temp

causes 6-7% change in BrAC

hypoventilation

subject induced raised BrAC

hyperventilation

subject induced lowered BrAC

2100:1 BBR, lowest reported sample, truncated results, breath temperature correction

four mechanisms to eliminate subject bias

Francis Edmund Anstie

used potassium dichromate and sulfuric acid to determine concentration of EtOH in blood, breath, and urine

Sir Edward Mellanby

first to establish blood-ethanol time course

Emil Bogen

first US scientist to correlate alcohol in breath and urine with clinical test of drunkeness

Dr. Rolla Harger

developed the drunk-o-meter in 1938

Robert F. Borkenstein

debuted the breathalyzer in 1956

potassium permanganate

substance used in drunkometer

iodine pentoxide

substance used in alcometer

Greenburg

created of the alcometer

Forrester

creator of the intoximeter

potassium dichromate

substance used in the breathalyzer

IR spectroscopy

the study of the interaction of matter with infrared radiation

Beer-Lambert Law

A=Ebc

IR spectrum of ethanol

IR spectrum of methanol

IR spectrum of acetone

electrochemical cell

a device capable of either deriving electrical energy from chemical reactions, or facilitating chemical reactions through the introduction of electrical energy

fuel cell

reversible, an electrochemical cell, which continuously transforms the chemical energy of a fuel and an oxidation material into electrical energy

cal check 0.02, subject test, air check, subject test, cal check 0.08, cal check 0.15

DUI test sequence

HGN and VGN, LOC, slow reaction to light, increase pulse, varied blood pressure and temperature, muscle tone may be flaccid

inhalant DRE characteristics

confusion, disoriented, flushed face, watery eyes

inhalant general indicators

potentiate the GABA receptor function

some inhalants _________ leading to enhanced inhibitory neurotransmission causing sedation, muscle relaxation, and anxiolytic effects

antagonist at the NMDA receptor

certain inhalants (like nitrous oxide) act as ___________ which reduces excitatory neurotransmission and contributes to the dissociative effects, altered perception, and analgesia

intoxication, disorientation, impaired judgement, hallucinations, ataxia

acute effects of inhalants

PNS and CNS dysfunction, liver or kidney failure, dementia, loss of cognitive functions, loss of coordination

chronic effects of inhalants

1,1-diluoroethane

an organofluorine compound commonly used as an aerosol propellant, commonly used in refrigerants, spray cleaners, hair spray, and spray deodorants

infrared

alcohol absorbs light at a particular IR wavelength, causing a decreased intensity of IR energy reaching the detector

multi wavelength IR detector

compares the absorption at different wavelengths and verify the ratio between wavelengths is correct for ethanol

electrochemical

alcohol from a breath sample is oxidized and a current is produced

hypnotics, anxiolytics, anesthetics, spasmolytics, anticonvulsants

types of depressants

slow reflexes, impaired social inhibitions, impaired divided attention, impaired judgment, increased risk taking, emotional instability

depressant characteristics

barbiturates, muscle relaxers, benzodiazepines, z-drugs, others

depressant classes of drugs

sedative-hypnotics, anticonvulsants, migraine therapy

barbiturate common uses

serious drug interactions, severe withdrawal, high tolerance, CNS depression

disadvantages of barbiturates

inhibition of nerve transmission in the CNS, increases affinity of GABA for its receptor

barbiturate mode of action

sedation, hypnosis, coma, death

results of CNS depression

respiratory depression

the hypoxic and chemoreceptor response to CO2 is suppressed

short acting barbiturates

used as an induction agent for surgical anesthesia and in the treatment of head injury as it lowers pressure and reduces oxygen demand

intermediate acting barbiturates

used alone as a sedative-hypnotic or in combination with ASA and caffeine for migraines

long acting barbiturates

used in treatment of seizures

absorbed orally, lipophilic, metabolized by liver

pharmacokinetics of barbiturates

meprobamate, cyclobenzaprine, methocarbamol

three common muscle relaxers

soma

carisoprodol as parent drug with meprobamate as metabolite

miltown

just meprobamate prescribed

meprobamate mode of action

works by blocking interneuronal activity in the spinal cord, but does not directly relax tense skeletal muscles

cyclobenzaprine

related to TCAs, used for muscle spasm cause by local tissue trauma or muscular strains

significant first pass effect, phase I metabolism

benzodiazepine pharmacokinetics

nordiazepam and oxazepam

diazepam and chlordiazepoxide both metabolize to _________

increase inhibition of GABA

benzodiazepine pharmacodynamics

high performance liquid chromatography

uses high pressure to force solvent or liquid mobile phases through closed columns containing fine particles that give high resolution separations

high, low

_____ polarity of stationary phase and ____ polarity of mobile phases in HPLC

adsorption, partition, ion exchange, size exclusion

four types of liquid chromatography

adsorption chromatography

separation is based on interaction between the solute molecules and the active sites on the stationary phase

partition chromatography

separation is based upon differences in partition coefficient or solubility

solvent tray, degasser, pump, autosampler, column, detector

order of LC schematic diagram

solvent tray

mobile phase bottles are placed here

degasser

used to eliminate the formation of air bubbles in mobile phases

pump

force solvent through the system

autosampler

automated injection system that is used to introduce sample onto column

column

where separation happens

detector

produce identification signals

one aqueous and one organic

two mobile phases in LC

isocratic pump

deliver constant mobile phase composition

gradient pump

deliver variable mobile phase composition

binary gradient pump

deliver two solvents

quaternary gradient pump

deliver four solvents

silica gel

usually column packing because of particle shape and pore structure that provides good separation

reversed phase, normal phase, ion pair, ion exchange, size exclusion

types of column

guard column

used to remove particulate matter and contaminant

retention time

time taken for the analyte to travel from the column to the detector

column efficiency increases

as number of theoretical plates increases, ________________

number of theoretical plates increases

as height equivalent to a theoretical plate decreases, ___________

gas chromatography

a separation technique that takes place in a column that has a continuous flow of mobile phase passing through it, usually in an inert carrier gas, maintained in a temperature controlled oven

carrier gas, flow controller, sample injector, column oven, column, detector, waste

parts of a gas chromatograph

inlet

manual or automatic injector on a gas chromatograph

septum, o-ring, inlet liner, inlet seal and washer

parts of an inlet

heated injection port

hot enough to vaporize samples, low enough to avoid thermal degradation

septum

high temperature silicone rubber, used to maintain pressure

inlet liner

deactivated tubes used to provide heating of samples and reduce column contamination, may be packed with glass wool

oven

used to maintain temperature, can run a temperature program

temperature program

ramps temperature throughout the run at a constant rate, ideal for mixtures containing compounds with a wide range of boiling points

flame ionization, nitrogen phosphorus, electron capture, mass spectrometer

GC detectors

flame ionization detector

uses an air-hydrogen flame to produce ions, can only detect compounds that are able to be burned

UV-Vis, triple quadrupole, ion trap, time-of-flight

LC detectors

single quadrupole

sorts molecules based on mass/charge

mass analyzer, collision cell, mass analyzer

order of a triple quadrupole

collision induced dissociation

fragments molecules by passing them through a field of inert gas (commonly nitrogen)

time of flight

allows us to identify a compound out to four decimal places