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Drug Identification
• In what types of situations would a
forensic scientist need to test for drugs?
• In what ways can forensic scientists test
for drugs? (What types of biological
samples would they use to test for
drugs?)
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
5-1
Most common drug tests
• Urine drug test (urinalysis)
– Test card is used on site for immediate results, or
sample is sent away to a lab to be tested with a
sophisticated gas analyzer.
– To prevent substitution of another person's urine or an
adulterating substance, one is sometimes observed
while urinating. While some people attempt to defeat
a urine test by drinking copious amounts of water, a
sufficiently diluted sample may be rejected.
– Some herbal extracts are marketed for "detox" of
controlled substances from one's urine, but their
efficacy is controversial.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
5-2
Most common drug tests
• Hair Follicle drug test
– Hair testing is quite accurate
– Can go back 6 months (timeline!)
– Many people try to get around this by just
shaving their heads.
– This is ineffective, as hair from one's
underarm, pubic, leg or arm hair can also
be used.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
5-3
Most common drug tests
• Blood drug test
– Blood testing is usually performed for serious
employment positions or by insurance
companies. This is expensive and not very
common.
– Toxicologists can use blood samples to analyze
overdoses or poisonings.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
5-4
Most common drug tests
• Saliva drug test
– This is not common and can only detect toxins
used 3-4 days prior. Insurance companies and
law enforcement agencies use this method most
often.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
5-5
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 (Presumptive) test: ?
– Confirmation test: a single test that specifically
identifies a substance.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
5-6
Screening Tests
• Screening (Presumptive) Tests:
– Why use them?
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
5-7
Preliminary Analysis
• The unknown substance may be any one
of a thousand or more commonly
encountered drugs.
• Screening tests reduce these possibilities
to a small and manageable number.
• A series of color tests that will produce
characteristic colors for the more
commonly encountered illicit drugs.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
5-8
Type of Test
Chemicals
What the Results Mean
Marquis Color
Formaldehyde and concentrated sulfuric acid
Heroin, morphine and most opium-based
drugs will turn the solution purple.
Amphetamines will turn it orange-brown.
Cobalt thiocyanate
Cobalt thiocyanate, distilled water, glycerin,
hydrochloric acid, chloroform
Cocaine will turn the liquid blue.
Cobalt acetate and isopropylamine
Barbiturates will turn the solution violetblue.
P-dimethylaminobenzaldehyde, hydrochloric
acid, ethyl alcohol
LSD will turn the solution blue-purple.
Dillie-Koppanyi
VanUrk
Duquenois-Levine Test
Vanillin, acetaldehyde, ethyl alcohol,
chloroform
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
Marijuana will turn the solution purple.
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
5-9
Preliminary Analysis
• Microcrystalline tests:
– Analyze the size and shape of crystals formed when
the drug is mixed with specific reagents.
Fig. 3. Microcrystalline response of
selected psychoactive stimulants tested
with mercury chloride as reagent (a)
BZP, (b) caffeine, (c) D-amphetamine,
(d) DL-amphetamine, (e) ephedrine
hydrochloride, (f) ephedrine sulphate,
(g) MDAI freebase, (h) mephedrone, (i)
methamphetamine. Note: (a) was taken
at 76× magnifications, images (b)–(i)
were taken at 19× magnifications.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
5-10
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 gas
chromatography-mass spectrometry is used to
specifically identify a drug substance.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
5-11