Presumptive Drug Tests

1
Presumptive Drug Tests

• Screening for drugs or
• What could that white powder be?

2
Presumptive Tests

• Pros
• Quick, inexpensive, on the scene
• Can be used for elimination purposes
• Cons
• Cannot be used in court
• Do not definitively identify a drug
• Do not quantify amount

3
Controlled Substance Analysis
Unknown Substance
Screening Tests Chemical Color Micro
Crystal TLC GC/FID UV/Vis
Yes
No
Plant?
Macroscopic Examination
Yes
Microscopic Examination
Yes
Yes
Confirmation Tests Micro Crystal GC/MS IR
Chemical Exam Duquenois TLC GC/FID GC/MS
4
Marijuana

• Cannabis sativa
• Macroscopic Tests
• Palmate leaf with serrated edges
• Fluted stems
• Red thread in bud
• Microscopic Tests
• Bear claw shaped hairs on top surface of leaf
• Small crystals at base of leaf

http//www.dps.state.ia.us/DCI/Crime_Lab/Controlle
d_Substance/marij.shtml
5
Hashish

• 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
6
Duquesnois-Levine Test

• 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
7
Thin Layer Chromatography

• 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/Controlle
d_Substance/add_tests.shtml
8
Proving Its Pot

• Three tests must be positive!
• Microscopic botanical characteristics present?
• Positive Duquenois Levine Test?
• Positive TLC?

9
Peyote

• Macroscopic
• Buttons 1 in diameter
• 5-10 orange like segments
• White tuft in each segment
• Chemical Test
• Chromatography to identify characteristic pattern
  of alkaloids
• Mescaline is active ingredient

10
Magic Mushrooms

• Psilocybe cubensis
• Off white stems with blue-gray staining
• Off white to tan caps
• Active ingredients
• psilocin
• psilocybin

11
Magic Mushrooms

• Characteristic UV spectra
• Separate Using TLC then use UV light to image
  spots
• Color Tests
• Purple with pDMBA (Van Urks)
• Red with fast blue B that then turns blue when
  HCl is added

12
Magic Mushrooms

• Possession of mushrooms is not illegal
• 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)
13
Magic Mushrooms

• Psilocybin will break down during gas
  chromatography
• 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
• Cant separate psilocin from psilocybin

14
Chemical Color Tests

• Use reagents that produce specific colors when
  reacting with certain classes of compounds
• Target the functional groups
• Phenols
• Aromatic rings
• Primary, secondary and tertiary amines
• Chemically adding an auxochrome to drug molecule
  that shifts the optical absorption into the
  visible

15
Chemical Color Tests

• Detection limits of 1 to 50 µg
• Can be used as developers for TLC plates

16
Chemical Color Tests

• Need positive and negative controls to ensure
  reagents are reliable
• Colors are influenced by
• Examiners subjectivity
• Concentration
• Diluents
• Adulterants
• Age of reagent
• Length of time reaction is observed

17
Color Tests
Methamphetamine/ Marquis Reagent 2 formaldehyde
in Sulfuric acid
Heroin/ Marquis Reagent
Methamphetamine/ Sodium Nitroprusside
Heroin/ Mecke Reagent
http//www.dps.state.ia.us/DCI/Crime_Lab/Controlle
d_Substance/cct.shtmlphoto8
18
Color Test Kits

• 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 h
ttp//shop.armorforensics.com/mm5/merchant.mvc?Scr
eenPRODStore_Code RedwopProduct_Code7624Cate
gory_Codenarcotest
19
Color Test Sequences
Narcotics or Amphetamines White precip
Barbituates No precip
Mayers
Demerol brown
Opiates purple
Marquis
Dillye- Koppanyi
Ecstasy black
Nitric Acid
Mescaline red
Amphetamines Orange to red to brown
Barbituates blue
Mandelins
Methadone Dark blue
16 different tests are available
Heroin yellow
Morphine Red to orange to yellow
Amphetamines Olive green confirms
http//www.bvda.com/EN/prdctinf/pf_en_np.html
20
Microcrystal Tests

• 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
• 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/Date20rape
20research.htm
21
Microcrystalline Tests
Cocaine
Methamphetamine
http//www.dps.state.ia.us/DCI/Crime_Lab/images/bl
ue42.jpg
22
Thin Layer Chromatography

• The trick is getting the compounds out of the
  solid sample and on the plate
• Chemical Extractions
• Physical extraction
• Dry wash and dry extraction
• Liquid/liquid extractions

23
Types of Drugs

• 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 dont have an associated salt form

24
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 Insoluble Soluble
Organics Free acid is Soluble Free base is Soluble Soluble
25
Liquid/Liquid Extraction

• Dissolve in acidic aqueous solution
• Basic drugs dissolve
• Add organic solvent and shake
• Acid and neutral drugs go into organic
• Remove organic solvent after separation
• Make aqueous solution basic
• Basic drugs become insoluble
• Add second organic and agitate
• Basic drugs dissolve in organic
• Separate solvents
• Use organic fraction for IR or GC/MS