A gas chromatograph is a sensitive laboratory instrument that can be used to separate and identify volatile components in a forensic sample. Which of these four samples would be most suitable for analysis using this technique?
Metal fragments from a bomb
An accelerant in an arson
Gas chromatography (GC) requires that the forensic sample to be analyzed is in the gas phase, hence it is most suitable for samples which easily can turn into gases (volatile compounds). This forensic gas sample, often containing
During the centuries that followed the publication of a Chinese book in 1248 about finding a murderer many discoveries were made and many theories recognized. By 1773 a Swedish chemist could detect a substance in corpses and by 1806 a German scientist cou
Scheele, the Swede, could detect arsenic in large doses in a cadaver, and Ross, the German, found it in smaller doses in the lining of the stomach. By 1836 James Marsh, an English chemist, confirmed that it was the poison used for murder in a trial. Later
Hair can serve as an historical marker for determining drug in-take
True
Morphine is the milky sap that oozes from the poppy pod when it is scored.
False, it is opium
Morphine is an analgesic and narcotic drug obtained from opium and used medicinally to relieve pain
Psilocin and psilocybin are naturally occurring hallucinogens that are found in:
A type of mushroom
The Duquenois-Levine test is a screening test for which drug?
Marijuana
A presumptive color test for the presence of cannabinoids
The Duquenois reagent (aldehyde and vanillin) mixed with hydrochloric acid yields a bluish-violet hue when the cannabinoids are present
The Scott color test is a screening test for which drug?
Cocaine
The drugs morphine, heroin, methadone, and codeine belong to which category of drug?
Depressants
The liquid-liquid extraction technique is part of the crystal screening test for drugs.
False
The peyote cactus contains a controlled substance that can be used legally in Native American religious rites.
True
The principle narcotic drug found in opium is known as:
Morphine
The role of the forensic toxicologist is limited to matters that pertain to violations of the law
False
The science which examines the effects of extraneous materials such as poisons on the human body is known as:
Toxicology
The technique used most widely by forensic toxicologists for deterring alcohol in blood is the gas chromatograph
True
Which of the following drugs is not a depressant?
diazepam
alcohol
Cocaine
methaqualone
Cocaine
Which of the following drugs, often used by veterinarians as a tranquilizer, have been used to facilitate sexual assaults?
Ketamine
Who is considered the father of modern toxicology?
Mathieu Orfila
Orfila helped establish toxicology as a scientific discipline. He is also credited as the first person to attempt to use the microscope to assess blood and semen stains.
With prolonged use of a drug, an individual may become less responsive to a drug's effects and may be able to tolerate blood-drug concentrations that would normally be fatal to the casual drug user.
True
Forensic toxicology
Detection
Quantification
Interpretation
Of foreign compounds (xenobiotics) in forensic samples
Sample preparation
Transformation of the sample into a suitable form for analysis
Concentration and cleans
Protein precipitation - adds a solvent that precipitates all the solids from the blood - alcohol
Liquid-liquid extraction - add base or acid to the blood - common basi
Liquid chromatography-mass spectrometry
Liquid mobile phase
Separates mixtures over time - based on their polarity
Retention time
Gas chromatography-mass spectrometry
Fine capillary column
Oil lining
Come out at different rates depending on chemical characteristics
Get a retention time - compared to known times in order to identify the drug - all kinds of chromatography
The drug is separated by the gas chromatography a
Infrared spectrophotometry
An infrared spectrum is unique to each individual chemical compound (except certain isomers and homologs).
Infrared spectrophotometers often come with computerized, searchable spectral libraries that aid in identification of the spectrum.
One drawback to
Pharmacokinetics
The science of pharmacokinetics studies how drugs move into and out of the body.
Four processes define pharmacokinetics. At times, only one or two of these processes are taking place; at other times all four are going on simultaneously. The four processes
The forensic toxicologist must accomplish a number of tasks in order to reach conclusions about the role of a drug in causing death:
� Determine the identity of all drugs and poisons present in the body
� Determine the quantities of all drugs and poisons present at the time of death
� Determine what metabolites (secondary products of drugs as they are acted on by the liver) of these dr
Screening
Screening tests are a type of preliminary test for drugs in body fluids. They are designed to give a preliminary result that indicates a drug may be present, but they do not absolutely confirm the presence of a drug.
Screening tests fall into two general
Confirmation
Once a screening test has been completed, any drugs indicated must be confirmed. The only accepted method for drug confirmation in forensic toxicology is mass spectrometry.
Cut off levels
Every analytical technique, be it mass spectrometry or a screening test, has a limit of detection�that is, a level below which a reliable result cannot be determined.
The reason is that every instrument creates some electronic noise that shows up in the c
Alcohol in the Breath
Diffusion of oxygen and carbon dioxide are exchanged between the blood and air through these alveoli. If there is alcohol in the blood, then it too is eliminated through the alveoli and is exhaled from the mouth and nose.
2100:1 (1ml of blood contains as
Gas Chromatography - Blood alcohol levels
Blood is the preferred medium for blood alcohol measurement because it provides the best surrogate for brain alcohol levels