Presumptive Drug Tests

Screening for drugs or

“What could that white powder be?”

Retrieved from: http://www.whrhs.org/site/handlers/filedownload.ashx?moduleinstanceid=1289&dataid=1245&FileName=Presumptive_Drug_Tests.ppt

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

Controlled Substance Analysis

Unknown Substance

Plant?

ConfirmationTests

Micro CrystalGC/MS

IR

Microscopic Examination

MacroscopicExamination

Screening TestsChemical ColorMicro Crystal

TLCGC/FIDUV/Vis

Chemical ExamDuquenois

TLCGC/FIDGC/MS

NoYes

Yes

Yes

Yes

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

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

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

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

Proving It’s Pot

Three tests must be positive! Microscopic botanical characteristics

present? Positive Duquenois Levine Test? Positive TLC?

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

Magic Mushrooms

Psilocybe cubensis Off white stems

with blue-gray staining

Off white to tan caps

Active ingredients psilocin psilocybin

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

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)

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

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

Chemical Color Tests

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

plates

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

Color Tests

Methamphetamine/Marquis Reagent2% formaldehyde inSulfuric 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

Add suspected substance to the pouch.

Seal Break ampoules in

order Check for color

change

http://www.crime-scene.com/ecpi/A-800-60XX.shtmlhttp://shop.armorforensics.com/mm5/merchant.mvc?Screen=PROD&Store_Code=Redwop&Product_Code=7624&Category_Code=narcotest

Color Test Sequences

Mayer’s

Narcotics orAmphetaminesWhite precip

BarbituatesNo precip

MarquisDillye-

Koppanyi

Opiatespurple

AmphetaminesOrange to red tobrown

Demerolbrown

Mescalinered

Ecstasyblack

Nitric Acid

Heroinyellow

MorphineRed to orange to yellow

Barbituatesblue

Mandelin’s

AmphetaminesOlive green confirms

MethadoneDark blue

http://www.bvda.com/EN/prdctinf/pf_en_np.html

16 different tests areavailable

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

Microcrystalline Tests

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

Cocaine Methamphetamine

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

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

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

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