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