Forensic Drug Forensic Drug AnalysisAnalysis

Chapter 5 DrugsChapter 5 Drugs

Screening and ConfirmationScreening and Confirmation

Forensic Scientists determine the Forensic Scientists determine the identity of drugs using…identity of drugs using…

Screening Tests – Screening Tests – preliminary tests preliminary tests used to reduce the # of possible used to reduce the # of possible identities of an unknown substance identities of an unknown substance (color tests & microcrystalline tests)(color tests & microcrystalline tests)

Confirmation – Confirmation – a single test that a single test that specifically identifies a substance.specifically identifies a substance.

Qualitative vs. QuantitativeQualitative vs. Quantitative

Identification of drugs may be…Identification of drugs may be… Qualitative – Qualitative – descriptive (An descriptive (An

unknown sample may be determined unknown sample may be determined to contain heroin and quinine.)to contain heroin and quinine.)

Quantitative-Quantitative-amount (A sample may amount (A sample may be determined to contain 10 % be determined to contain 10 % heroin and 90% quinine)heroin and 90% quinine)

Color TestsColor Tests

When mixed with a When mixed with a certain reagent, a certain reagent, a drug can produce a drug can produce a characteristic colorcharacteristic color

Useful for field Useful for field investigatorsinvestigators

Screening tests onlyScreening tests only YouTube - Spray drug YouTube - Spray drug

test kit for Cocaine restest kit for Cocaine residue detectionidue detection

Heroin

Meth

Color TestsColor Tests

Marquis – heroin, morphine, opium Marquis – heroin, morphine, opium derivatives, amphetaminesderivatives, amphetamines

Dille-Koppanyi-barbituratesDille-Koppanyi-barbiturates Duquenois-Levine – marijuanaDuquenois-Levine – marijuana Van Urk – LSDVan Urk – LSD Scott test - cocaineScott test - cocaine

Microcrystalline TestsMicrocrystalline Tests

A test that A test that identifies a specific identifies a specific substance based substance based on the color and on the color and shape of crystals shape of crystals formed when the formed when the substance is mixed substance is mixed with specific with specific reagents.reagents.

Methamphetamine

ChromatographyChromatography

An analytical technique An analytical technique used to separate the used to separate the components of a components of a mixture for the mixture for the purpose of purpose of identification and identification and quantification.quantification.

Useful to forensic Useful to forensic scientists because scientists because drugs often come in drugs often come in the form of a mixturesthe form of a mixtures

ChromatographyChromatography

All types of chromatography include:All types of chromatography include: Stationary Phase Stationary Phase – a solid substance used – a solid substance used

to adsorb components of a mixture.to adsorb components of a mixture. Mobile Phase Mobile Phase – a liquid or gas that flows – a liquid or gas that flows

through the stationary phase. through the stationary phase. Components of a mixture are separated Components of a mixture are separated

based on the speed that they move based on the speed that they move through the stationary phase.through the stationary phase.

The speed of a substance depends on how The speed of a substance depends on how strongly it is attracted to the mobile and strongly it is attracted to the mobile and stationary phases.stationary phases.

Thin-Layer ChromatographyThin-Layer Chromatography

TLC uses a solid TLC uses a solid (silica gel or (silica gel or aluminum oxide) aluminum oxide) coated on a plastic coated on a plastic or glass plate.or glass plate.

The plate is The plate is immersed in a immersed in a liquid solventliquid solvent

YouTube - Thin LayYouTube - Thin Layer Chromatographyer Chromatography of Felt Tipped Pens of Felt Tipped Pens

Thin Layer ChromatographyThin Layer Chromatography

As the solvent As the solvent travels up the travels up the chromatogram, chromatogram, components of a components of a mixture travel at mixture travel at different speeds.different speeds.

Unknown Unknown substances can be substances can be compared to compared to reference samples.reference samples.

Gas ChromatographyGas Chromatography

GC – solid stationary GC – solid stationary phase/gaseous mobile phase/gaseous mobile phasephase

Complex mixtures can Complex mixtures can easily be analyzedeasily be analyzed

Quantitative results Quantitative results can be obtainedcan be obtained

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SpectrophotometrySpectrophotometry

UV, Visible, and Infrared Light can be UV, Visible, and Infrared Light can be used to analyze unknown substancesused to analyze unknown substances

Substances absorb, reflect, or Substances absorb, reflect, or transmit various wavelengths of transmit various wavelengths of light.light.

This property can be used to This property can be used to indentify or quantify unknown indentify or quantify unknown substances.substances.

UV-Visible SpectrophotometryUV-Visible Spectrophotometry

The absorption of UV or visible light The absorption of UV or visible light can be used to indentify or quantify can be used to indentify or quantify an unknown substancean unknown substance

Identification is not exact; other Identification is not exact; other substances can have similar substances can have similar absorption spectraabsorption spectra

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UV-Visible SpectrophotometryUV-Visible Spectrophotometry

Infrared SpectrophotometryInfrared Spectrophotometry

Unknown substances can be Unknown substances can be analyzed by measuring the analyzed by measuring the absorption of infrared light.absorption of infrared light.

The absorption pattern is much more The absorption pattern is much more complex than UV.complex than UV.

Substances can be specifically Substances can be specifically identified by their IR spectrum (like a identified by their IR spectrum (like a fingerprint)fingerprint)

Infrared SpectrophotometryInfrared Spectrophotometry

Mass Spectrometry

Often used as a detector for Gas Often used as a detector for Gas ChromatographyChromatography

A substance is bombarded with high-A substance is bombarded with high-energy electronsenergy electrons

This causes the substance to ionize.This causes the substance to ionize. The ions break up into smaller The ions break up into smaller

fragments.fragments. The fragments are separated by massThe fragments are separated by mass The fragmentation pattern is unique to The fragmentation pattern is unique to

each individual substanceeach individual substance

Mass SpectroscopyMass Spectroscopy