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Presumptive Drug Tests PowerPoint PPT Presentation


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Presumptive Drug Tests. Screening for drugs or “What could that white powder be?”. 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.

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Presumptive Drug Tests

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Presumptive drug tests l.jpg

Presumptive Drug Tests

Screening for drugs or

“What could that white powder be?”


Presumptive tests l.jpg

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


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Controlled Substance Analysis

Unknown

Substance

Yes

Screening Tests

Chemical Color

Micro Crystal

TLC

GC/FID

UV/Vis

No

Plant?

Macroscopic

Examination

Yes

Microscopic

Examination

Yes

Yes

Confirmation

Tests

Micro Crystal

GC/MS

IR

Chemical Exam

Duquenois

TLC

GC/FID

GC/MS


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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/Controlled_Substance/marij.shtml


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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


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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


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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/Controlled_Substance/add_tests.shtml


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Proving It’s Pot

  • Three tests must be positive!

    • Microscopic botanical characteristics present?

    • Positive Duquenois Levine Test?

    • Positive TLC?


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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


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Magic Mushrooms

  • Psilocybe cubensis

    • Off white stems with blue-gray staining

    • Off white to tan caps

  • Active ingredients

    • psilocin

    • psilocybin


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Magic Mushrooms

  • Characteristic UV spectra

  • Separate Using TLC then use UV light to image spots

  • Color Tests

    • Purple with pDMBA (Van Urk’s)

    • Red with fast blue B that then turns blue when HCl is added


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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)


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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

    • Can’t separate psilocin from psilocybin


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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


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Chemical Color Tests

  • Detection limits of 1 to 50 µg

  • Can be used as developers for TLC plates


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Chemical Color Tests

  • Need positive and negative controls to ensure reagents are reliable

  • Colors are influenced by

    • Examiner’s subjectivity

    • Concentration

    • Diluents

    • Adulterants

    • Age of reagent

    • Length of time reaction is observed


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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/Controlled_Substance/cct.shtml#photo8


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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

http://shop.armorforensics.com/mm5/merchant.mvc?Screen=PROD&Store_Code

=Redwop&Product_Code=7624&Category_Code=narcotest


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Color Test Sequences

Narcotics or

Amphetamines

White precip

Barbituates

No precip

Mayer’s

Demerol

brown

Opiates

purple

Marquis

Dillye-

Koppanyi

Ecstasy

black

Nitric Acid

Mescaline

red

Amphetamines

Orange to red to

brown

Barbituates

blue

Mandelin’s

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


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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/Date%20rape%20research.htm


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Microcrystalline Tests

Cocaine

Methamphetamine

http://www.dps.state.ia.us/DCI/Crime_Lab/images/blue42.jpg


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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


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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 don’t have an associated salt form


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Solubility Guidelines


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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


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