drug identification. the challenge of forensic drug identification comes in selecting the correct...
DESCRIPTION
Controlled Substance Analysis Unknown Substance Plant? Confirmation Tests Micro Crystal GC/MS IR Microscopic Examination Macroscopic Examination Screening Tests Chemical Color Micro Crystal TLC GC/FID UV/Vis Chemical Exam Duquenois TLC GC/FID GC/MS No YesTRANSCRIPT
Drug Identification
Drug Identification
The challenge of forensic drug identification comes in selecting the correct procedure(s) that will ensure a specific identification of a drug
3 ways to identify drugs1. PDR- Physician’s Desk Reference2. Laboratory Tests- conclusive tests3. Field Tests- presumptive tests
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
PDR
Physician’s Desk Reference A quick and an easy identifier of
manufactured pills, tablets, and capsules Updated each year Provides:
a picture of a drug, whether it is a prescription, over the counter, or a
controlled substance, other detailed information about the drug
Presumptive Tests
A presumptive test is an analysis of a sample which establishes either:
The sample is definitely not a certain substance (“rule out”)
Probable identification (“could be…”)
Presumptive Tests
Pros Quick, inexpensive, on the scene Can be used for elimination purposes
Cons Cannot be used in court Does not definitively identify a drug Does not quantify amount
Presumptive Tests
Include:1. Spot or color tests2. Microcrystalline test
Spot or Color Tests
Use reagents that produce specific colors when reacting with certain classes of compounds Chemically adding an auxochrome to drug
molecule that shifts the optical absorption into the visible spectrum
Need positive and negative controls to ensure reagents are reliable
Spot or Color Tests
Colors are influenced by Examiner’s subjectivity Concentration of sample Diluents Adulterants (impure) Age of reagent Length of time reaction is observed
Spot or Color TestsTest Name Indicator for… Results in…Marquis Most opium
derivatives (heroin, morphine)
Purple
Amphetamines Orange-brownDillie-Koppanyl Barbiturates Violet-blueDuquenois-Levine
Marijuana Purple
VanUrk LSD Blue-purpleScott test Cocaine Blue
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
Color Test Sequences
Mayer’s
Narcotics orAmphetaminesWhite precip
BarbituatesNo precip
Marquis Dillye-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
Confirmatory Tests
Can determine the exact identity of the substance
Includes…Spectroscopy
• Ultraviolet (UV)• Visible• Infrared (IR)
Screen solid samples for potential illicit substances
Chromatography (liquid/gas)• Microcrystalline
Confirm that the illegal substance is present and to identify it
Mass spectrometry Systematically quantified
Forensic Autopsy
Look for Irritated tissues Characteristic odors Mees line
Single transverse white bands on nails
Order toxicological screens to identify all the drugs and toxic compounds that are potentially present in a sample
Human Specimens for Analysis
Blood Urine Vitreous humor of eye Bile Gastric contents Liver tissue Brain tissue Kidney tissue Hair Nails
Spectroscopy
The interaction of electromagnetic radiation (light) with matter
Measured using a spectrophotometer An instrument used to measure and
record the absorption spectrum (absorbed/reflected) of a chemical substance
Spectrophotometer
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
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
Microcrystal Tests Sample is dissolved in solution Reagent is added generating a
precipitate, which will have 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
Microcrystalline Tests
http://www.dps.state.ia.us/DCI/Crime_Lab/images/blue42.jpg
Cocaine Methamphetamine
Mass Spectrometry In a mass spectrometer, an electron beam is
directed at sample molecules in a vacuum chamber
The electrons break apart the sample molecules into many positively charged pieces that are sorted and collected according to their mass to charge ratio by a magnetic field
Pattern that results is used to identify the sample
Field Tests
Preliminary tests Used to determine the degree of
suspect’s physical impairment and whether or not another test is justified
Psychophysical tests 3 basic tests exist
Horizontal gaze nystagmus (HGN) Nine step walk and turn (WAT) One leg stand (OLS)
Field Tests
Horizontal gaze nystagmus (HGN Follow a pen or small flashlight, tracking left to
right with one’s eyes Wavering at 45 degrees indicates BAC of 0.10
Nine step walk and turn (WAT) Comprehend and execute two or more simple
instructions at a time One leg stand (OLS)
Maintain balance, comprehend and execute two or more simple instructions at one time
The Breathalyzer
More practical in the field Collects and measures alcohol content
of alveolar breath Breath sample mixes with 3 ml of
0.025% potassium dichromate in sulfuric acid and water Measures light absorption of potassium
dichromate before and after the reaction with alcohol
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
Heavy Metals and FertilizersType of Poison Symptom/EvidenceCaustic poison (lye) Burns around the lips and mouth Carbon monoxide Red or pink patches on chest & thighs
Sulfuric acid Black vomitHydrochloric acid Greenish-brown vomitNitric acid Yellow vomitPhosphorus Coffee brown vomit, onion or garlic odor
Cyanide Burnt almond odorArsenic, mercury Pronounced diarrheaMethyl (wood) or isopropyl alcohol
Nausea, vomiting, unconsciousness, blindness