Transcript Presumptive Drug Tests

Presumptive Drug Tests
Screening for drugs or
“What could that white
powder be?”
Presumptive Tests
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Pros
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Quick, inexpensive, on the scene
Can be used for elimination purposes
Cons
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Cannot be used in court
Do not definitively identify a drug
Do not quantify amount
Controlled Substance Analysis
Unknown
Substance
Yes
Macroscopic
Examination
Yes
Microscopic
Examination
No
Plant?
Screening Tests
Chemical Color
Micro Crystal
TLC
GC/FID
UV/Vis
Yes
Yes
Chemical Exam
Duquenois
TLC
GC/FID
GC/MS
Confirmation
Tests
Micro Crystal
GC/MS
IR
Marijuana
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Cannabis sativa
Macroscopic Tests
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Palmate leaf with
serrated edges
Fluted stems
Red “thread” in bud
Microscopic Tests
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Bear claw shaped
hairs on top surface
of leaf
Small crystals at
base of leaf
http://www.dps.state.ia.us/DCI/Crime_Lab/Controlled_Substance/marij.shtml
Hashish
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Resin from marijuana
that has been isolated
Cake is smoked
Oil is added to other
substances and
smoked
Contains concentrated
cannabinoids
http://www.dea.gov/photos/hash/hash2.jpg
Duquesnois-Levine Test
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Test for presence of cannabinols, the active agent in
marijuana
Duquenois agent is 2% vanillin, 1% acetaldehyde in ethanol
Purple color denotes a positive test
http://www.dea.gov/photo_library4.html
Thin Layer Chromatography
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Establishes the presence of specific
cannabinoids
Provides a color test
Positive if patterns match those of a known
reference run at the same time
http://www.dps.state.ia.us/DCI/Crime_Lab/Controlled_Substance/add_tests.shtml
Proving It’s Pot
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Three tests must be positive!
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Microscopic botanical characteristics
present?
Positive Duquenois Levine Test?
Positive TLC?
Peyote
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Macroscopic
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Buttons 1” in diameter
5-10 orange like
segments
White tuft in each
segment
Chemical Test
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Chromatography to
identify characteristic
pattern of alkaloids
Mescaline is active
ingredient
Magic Mushrooms
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Psilocybe cubensis
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Off white stems
with blue-gray
staining
Off white to tan
caps
Active ingredients
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psilocin
psilocybin
Magic Mushrooms
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Characteristic UV spectra
Separate Using TLC then use UV light
to image spots
Color Tests
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Purple with pDMBA (Van Urk’s)
Red with fast blue B that then turns blue
when HCl is added
Magic Mushrooms
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Possession of mushrooms is not illegal
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Proof of presence of psilocin or psilocybin is
necessary to convict
Psilocybin is fragile and easily converts to
psilocin, so you have to prove the psilocin
was there initially
psilocybin
psilocin
seratonin
(neurotransmitter)
Magic Mushrooms
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Psilocybin will break down during gas
chromatography
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Pre-react molecule to stabilize it
Use Mass Spectroscopy to identify the reaction product
Chemical extraction with methanol prior to IR can
break it down
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Can’t separate psilocin from psilocybin
Chemical Color Tests
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Use reagents that produce specific colors
when reacting with certain classes of
compounds
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Target the functional groups
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Phenols
Aromatic rings
Primary, secondary and tertiary amines
Chemically adding an auxochrome to drug
molecule that shifts the optical absorption
into the visible
Chemical Color Tests
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Detection limits of 1 to 50 µg
Can be used as developers for TLC
plates
Chemical Color Tests
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Need positive and negative controls to
ensure reagents are reliable
Colors are influenced by
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Examiner’s subjectivity
Concentration
Diluents
Adulterants
Age of reagent
Length of time reaction is observed
Color Tests
Methamphetamine/
Marquis Reagent
2% formaldehyde in
Sulfuric acid
Methamphetamine/
Sodium Nitroprusside
Heroin/
Marquis Reagent
Heroin/
Mecke Reagent
http://www.dps.state.ia.us/DCI/Crime_Lab/Controlled_Substance/cct.shtml#photo8
Color Test Kits
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Add suspected
substance to the
pouch.
Seal
Break ampoules in
order
Check for color
change
http://www.crime-scene.com/ecpi/A-800-60XX.shtml
http://shop.armorforensics.com/mm5/merchant.mvc?Screen=PROD&Store_Code
=Redwop&Product_Code=7624&Category_Code=narcotest
Color Test Sequences
Narcotics or
Amphetamines
White precip
Barbituates
No precip
Mayer’s
Demerol
brown
Opiates
purple
Marquis
DillyeKoppanyi
Ecstasy
black
Mescaline
red
Nitric Acid
Amphetamines
Orange to red to
brown
Heroin
yellow
Morphine
Red to orange
to yellow
Barbituates
blue
Mandelin’s
Methadone
Dark blue
Amphetamines
Olive green confirms
16 different tests are
available
http://www.bvda.com/EN/prdctinf/pf_en_np.html
Microcrystal Tests
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Sample is dissolved in
solution
Reagent is added
generating a precipitate
Precipitate has uniquely
shaped crystals
Must have a reference
standard using same
reagent
Potential problems
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Impurities can distort
crystal shapes
High concentration leads
to small crystals
Reagent age effects
GHB “date-rape drug”
Crystals following addition
Of silver nitrate
http://www.lincoln.ac.uk/fabs/Research/Date%20rape%20research.htm
Microcrystalline Tests
Cocaine
Methamphetamine
http://www.dps.state.ia.us/DCI/Crime_Lab/images/blue42.jpg
Thin Layer Chromatography
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The trick is getting the compounds out
of the solid sample and on the plate
Chemical Extractions
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Physical extraction
Dry wash and dry extraction
Liquid/liquid extractions
Types of Drugs
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Basic drugs have an acid (HCl, etc.) as
part of their salt form
Acidic drugs have a base (Na, K) as
part of their salt form
Neutral drugs don’t have an
associated salt form
Solubility Guidelines
Acidic Drugs
Basic Drugs
Neutral Drugs
Acidic Water
Solutions
Insoluble
Soluble
Soluble
Basic Water
Solutions
Soluble
Insoluble
Soluble
Neutral Water
Solutions
Free acid is
Insoluble
Free base is Soluble
Insoluble
Organics
Free acid is
Soluble
Free base is Soluble
Soluble
Liquid/Liquid Extraction
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Dissolve in acidic aqueous solution
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Add organic solvent and shake
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Basic drugs become insoluble
Add second organic and agitate
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Acid and neutral drugs go into organic
Remove organic solvent after separation
Make aqueous solution basic
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Basic drugs dissolve
Basic drugs dissolve in organic
Separate solvents
Use organic fraction for IR or GC/MS