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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 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 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 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 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 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 Cocaine Methamphetamine http://www.dps.state.ia.us/DCI/Crime_Lab/images/blue42.jpg 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 Soluble Insoluble Organics Free acid is Soluble Free base is Soluble Soluble Liquid/Liquid Extraction Dissolve in acidic aqueous solution Add organic solvent and shake Basic drugs become insoluble Add second organic and agitate Acid and neutral drugs go into organic Remove organic solvent after separation Make aqueous solution basic Basic drugs dissolve Basic drugs dissolve in organic Separate solvents Use organic fraction for IR or GC/MS
