Forensic toxicology involves the analysis of biological samples to determine the presence and amount of drugs, poisons, or other chemicals in the body for legal purposes. Key aspects of forensic toxicology include postmortem toxicology analysis from autopsy samples to determine the cause of death, as well as methodology for proper collection, storage, and analysis of various sample types like blood, urine, gastric contents and more. Proper specimen collection and handling is important to ensure accurate and interpretable toxicology results.

1. Forensic toxicology and
specimen collection

2. Forensic Toxicology
• The application of toxicology for the purposes of
the law.
• Greeks used hemlock as a means of state
sponsored execution. Socrates was the most
famous poisoning case by this method.
• In the U.S., forensic toxicology did not develop
until the early 20th century.
• Dr. Alexander Gettler is considered this country’s
first forensic toxicologist.
• Postmortem forensic toxicology.
• Human performance toxicology.
• Forensic drug testing.

3. Forensic toxicology…
 Drug intoxications are not readily diagnosed at autopsy.
 In IV drug deaths, there may be a recent injection site
observable;
 oral intoxications may be inferred by a large amount of
unabsorbed tablet fragments in the stomach contents.
 Otherwise, the only other anatomic findings are
pulmonary congestion and edema.

4. Forensic toxicology
• the function of the toxicology laboratory is
– to identify the substances present in the biologic specimens.
• Once these substances are identified, they are
quantitated in appropriate specimens to determine
whether these drugs caused or contributed to death.
• Forensic science task is to produce valid toxicological
information for the administration of justice and to
improve the legal protection of individuals and
society.

5. What is Forensic …..?
• As to the analysis of human samples, there
are two key questions:
– Has the person under investigation been exposed
foreign substances
– Has s/he been under the influence of alcohol,
drugs or other xenobiotics.

6. Postmortem Forensic
Toxicology
• Qualitative and quantitative analysis of drugs or poisons
in biological specimens collected at autopsy
– Forensic Pathologist responsible for performing
autopsy.
– Forensic Toxicologist responsible for analyzing
biological samples for poisons
• Interpretation of findings in terms of:
– Physiological effect at time of death
– Behavioural effect at time of death

7. Quantitative vs. Qualitative
• Qualitative analysis – determines the
presence or absence of a drug or poison in a
submitted sample
• Quantitative analysis – determines the
amount of drug or poison that is present in
the submitted sample

8. Postmortem Forensic
Toxicology
Types of cases:
• Suspected drug intoxication cases/Unexplained
deaths
• Arson fire deaths
• Homicides
• Motor vehicle fatalities/Driver and pilot fatalities
• Therapeutic drug monitoring
• Deaths due to natural causes
• Sudden infant death (SIDS)
 Death Investigations
– Coroner
– Medical Examiner

9. POST-MORTEM
TOXICOLOGY
• Analytical results of a post-mortem investigation
are utilized to determine the cause and manner of
death.
• Poisoning can be the:
– Underlying cause of death
• of morbid events leading directly to death
– Immediate cause of death
• with the symptoms of which the deceased
died

10. POST-MORTEM TOXICOLOGY
• Traditionally, the results of a single forensic case are
used for the sake of the deceased in question only.
• Over time, cases accumulate to form a greater whole,
which can provide information that goes far beyond the
original purpose of the routine casework.

11. TYPICAL FEATURES OF FATAL DRUG POISONINGS
• Frequently several drugs are present
• Frequently alcohol has been taken
simultaneously
• Frequently the victim has committed suicide
• Drugs of abuse are common
• Victims include young people also

12. THE MOST IMPORTANT
FINDING
• A combination of several drugs is typically found in
the same subject.
– If all findings are included in the classification,
the number of possible fatal combinations is too
high.
– The forensic pathologist always has a possibility to
choose the most important finding.
– If not stated, the drug which has the greatest
ratio of found concentration in relation to its
therapeutic concentration is taken as the basis of

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Areas of Application
• Postmortem drug testing –
– this is used in death investigations to establish whether
or not drugs were the cause or contributing factor in
death.
• Workplace drug testing –
– this consist of evaluation of biofluids, primarily urine
and blood from employees or job applicants for drug
content.
• Evaluation of Contraband –
– this is applied when evidence seized is being linked to

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Analytical Methods in Forensic Toxicology
• is important as the types of fluids that are tested.
• A good working relationship between death
investigators and laboratories is essential in success
of solving death investigations.
• Remember, death investigation is a team effort and
toxicology is a vital member of the team.

15. Analytical Methods ,,,,,
• Lab Expected to Provide
– Identification of agents/toxicant/ for poisoning
– Detection of drug abuse,i.e.in the victim blood.
– Therapeutic drug monitoring/for low TI drugs-w/c
are potentialy toxic/=TDM
• No- of cpds for which true emergency lab results are
needed to guide therapy are few
• For most, victims are treated empirically before lab
results are known

16. Analytical methods in (cont.)
• Information necessary for the lab="SATS"
– Suspected agent/substance
– Suspected amount
– Time of ingestion and sampling
– Clinical presentation
– Location of victim-where the exposure happens
• gives us information to assess more and how
the poisoning happens.
• to interview others who don’t come to clinics
while still poisoned.

17. Types of Specimen
• Urine
• gastric contents
• Blood
• bile
• CSF
• Vitreous Humor
• hair
• Nonbiologicals (scene residues)- staffs near the
victim where the poisoning occurs,OTC
medication,left over medication,empty bottles,,,,

18. Choice of Specimen
• Depends on
– Kinetics of the suspected agent
• For not absorbable agent/polar substance/: GI
specimen
• For absorbable agent/non polar toxicant/:
blood specimen
– Lab method
• For qualitative test: urine specimen/gastric
contents
• For quantitative tests: serum/whole blood
specimen

19. Specimen Collection
• Selection
– Multiple, varied sites of collection
• Collection
– Appropriate method of collection
– Adequate volumes for analysis
• Storage and handling
–Important to ensure analytical results are accurate
and interpretations are sound

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Specimen Collection
Blood
– the most satisfactory method for obtaining samples is
from venous puncture of the femoral vein.
– An alternate site to collect venous blood is to incise
the jugular.
– To be collected in sealed heparinized tube
– Could be whole blood, plasma, serum
– this is typically done after the neck has been exposed
under the sub-clavicular incision.
– The correlation between blood concentration and
effects of the drug is very high in blood testing.

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Specimen Collection
Urine
• is most often used to test for presence of drugs: because of the
types of test that can be run and the cost effectiveness of the
testing.
– Simple for collection
– 50ml to be collected
– Higher conc. of chemicals available and
• draw back:
– the correlation between drug concentration in urine and drug
effects is usually poor.
• Urine should also be collected in post mortem investigations since
some toxins show in higher levels in urine.

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Specimen Collection
Bile
• Because bile drains from the liver it is often times
very rich in certain types of drugs such as opiates.
• These toxins are concentrated by the liver and
excreted into the gall bladder.
• this can be useful in cases where morphine and
chlorpromazine are suspected toxins.
• Direct collection of bile into a bottle is advised
because bile is too viscous to be sucked through a
needle.

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Specimen Collection
Cerebrospinal Fluid
• not often collected for toxins, but may be needed
for microbiological analysis.
• If needed it should be collected by lumbar or
cisternal puncture.
– Cisternal puncture = Passage of a hollow needle
through the posterior anto-occipital membrane
into the cerebellomedullary cistern

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Specimen Collection
Vitreous Humor
• The fluid found in the center of the eye is the vitreous
humor.
• sometimes useful in bodies with appreciable post mortem
decay.
• The fluid in the eye resist putrefaction longer than other
body fluids.
• This is especially handy in a case in which there has been
a great deal of decomposition since vitreous humor may
be the only fluid still available to test.
• Vitreous can also be used at estimating time of death.

25. Collection of Specimens
gastric Contents
• Includes vomit, gastric aspirate, stomach wash (1st
sample/portion/ of washing)
• 20ml to be collected; Gives clue by smell
• Capsules or tablets to be identified by physical
inspection in the vomit
• is typically done in a sudden death in which the
decedent has large quantities of a lethal agent in his
stomach.
• Contents should be emptied into a wide mouth jar.
• In the case of suicide, large amounts of toxins in the
gastric tract may make this point apparent.

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Specimen Collection
• Hair
– Not common in forensics for a number of
reasons.
–Drugs only present in extremely low
concentrations.
–Controversy between active and passive
drug usage arise.
–The benefit of hair is that its is a good
timeline for drug usage since it is only
eliminated when hair is cut.

27. Collection of Specimens (Cont.)
Nonbiologicals (scene residues)
• Few mg is sufficient
• Sufficient amount need to be conserved
for further analysis
N.B. all should be collected before any
chemical admn./including drug/-b/c may
complicate the analysis and give false +ve
/-ve result.
soln.:-Therefore, after maintaining the
ABCD/supportive therapy/ you could take
specimen prior to adminstering drug for
symptomatic therapy.

28. Transport and /Storage of Specimen
• Need proper labeling-prior to transport.
• Organic solvent to be packed separate
from biological specimens to avoid cross
contamination-while transporting.
• All biological specimens to be stored at 4C°
• Some left over to be stored for medico-
legal purpose

29. Examination of Specimens
a. Physical Examination
I. Urine
• Color change: iron+deferroxamine=red
• Smell: methylsalicylate+reagent=strong
smell
• Appearance:
carbonates+reagent=turbidity
II. Stomach Contents
 Smell: alcohol smell, garlic smell
 pH:
 basic toxicants = high
 Acidic toxicants= low

30. Analytical methods in ...
• Spot tests: color change in urine/blood with
specific reagent
• UV spectroscopy: barbiturates
• Immunoassay: recognition by specific
antibodies (Abs) (opioids)
• Chromatography: TLC, GC ( for volatile cpds),
HPLC (for nonvolatile Cpds)
• Mass spectroscopy: almost for all(either
volatile or not)
• Nuclear magnetic resonance (NMR): most
sensitive(i.e, even to very small amt of
substance) but expensive

31. Analytic methods…

32. Human Performance Toxicology
• This branch of forensic toxicology is concerned with
the relationship between the presence of a drug and
associated behavioral changes.
• It is generally accepted that there is a dose-effect
relationship between drugs that elicit behavioral
changes and those changes;
• elucidation and quantification of such a relationship is a
significant role of the behavioral toxicologist.
• Human performance toxicology is also referred to as
behavioral toxicology.
– E.g Ethanol and driving

33. Breath Ethanol Testing
 Chemical
• Reaction of ethanol with potassium
dichromate/sulfuric acid solution
• Oxidation reaction with a color change from yellow
(dichromate ion) to green (chromic ion)
 IR Spectrophotometry
• Based on absorbance of light by the ethanol molecule
• Mainstay in evidential breath testing devices
 Electrochemical Oxidation
• Oxidation of ethanol to acetic acid
• Also used in evidential breath testing

34. Immunoassay
• Has the ability to
determine small
concentrations of drugs
in body fluids and
organs
• Best approach for
detecting low drug
levels in body
• Usually used for
marijuana screening

35. Color Tests
• Most drugs react with certain
chemicals to produce a specific
color
• Marquis: purple in heroine, opium.
Orange brown in
(meth)amphetamines
• Dilli-Kopanyi: violet in
barbiturates
• Duquenois-Levine: purple for
marijuana
• Van Urk: blue purple in LSD
• Scott test: blue, pink and blue

36. Microcrystalline tests
• A small drop of a
chemical is added to a
small amount of drug
which forms a crystalline
structure
• Size and shape of crystal
can be used to identify
drug

37. Spectrophotometry
• Identifies drug on based on
the type of light it absorbs
• Infraredspectrophotometry
can identify a specific drug
because infrared spectrum
is unique for all drugs
• Other types of
spectrophotometry are
sometimes inconclusive

38. Steps in Toxicological Analysis
1.Preanalytic Phase: Victim’s history and Physical
examination
2. Analytic Phase: Toxicological analysis-analysing the
subs. using the previous methods.
3. Post-analytic phase: Results’ interpretation /as to
come to conclusion/;
• Repeating analysis if need be

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Interpreting Findings
• Workplace drug testing is usually conducted for the
purpose of answering one of two questions
• History of drug use for hiring purposes
or
• explanation of erratic behavior of current employee.

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Interpreting Findings
• The goal of a forensic toxicologist is to confer with
the pathologist in determining the cause and manner
of death.
• In simple terms we infer that the death is due to a
specific toxin when appropriate quantities of that
toxin are found.
• When other findings conclude cause of death we may
specify the toxin as a contributing factor to death.