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Forensic Drug Analysis

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Presentation on theme: "Forensic Drug Analysis"— Presentation transcript:

1 Forensic Drug Analysis
Chapter 5 Drugs

2 Screening and Confirmation
Forensic Scientists determine the identity of drugs using… Screening Tests – preliminary tests used to reduce the # of possible identities of an unknown substance (color tests & microcrystalline tests) Confirmation – a single test that specifically identifies a substance.

3 Qualitative vs. Quantitative
Identification of drugs may be… Qualitative – descriptive (An unknown sample may be determined to contain heroin and quinine.) Quantitative-amount (A sample may be determined to contain 10 % heroin and 90% quinine)

4 Color Tests Heroin Meth
When mixed with a certain reagent, a drug can produce a characteristic color Useful for field investigators Screening tests only YouTube - Spray drug test kit for Cocaine residue detection Heroin Meth

5 Color Tests Marquis – heroin, morphine, opium derivatives, amphetamines Dille-Koppanyi-barbiturates Duquenois-Levine – marijuana Van Urk – LSD Scott test - cocaine

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

7 Chromatography An analytical technique used to separate the components of a mixture for the purpose of identification and quantification. Useful to forensic scientists because drugs often come in the form of a mixtures

8 Chromatography All types of chromatography include:
Stationary Phase – a solid substance used to adsorb components of a mixture. Mobile Phase – a liquid or gas that flows through the stationary phase. Components of a mixture are separated based on the speed that they move through the stationary phase. The speed of a substance depends on how strongly it is attracted to the mobile and stationary phases.

9 Thin-Layer Chromatography
TLC uses a solid (silica gel or aluminum oxide) coated on a plastic or glass plate. The plate is immersed in a liquid solvent YouTube - Thin Layer Chromatography of Felt Tipped Pens

10 Thin Layer Chromatography
As the solvent travels up the chromatogram, components of a mixture travel at different speeds. Unknown substances can be compared to reference samples.

11 Gas Chromatography GC – solid stationary phase/gaseous mobile phase
Complex mixtures can easily be analyzed Quantitative results can be obtained

12 Spectrophotometry UV, Visible, and Infrared Light can be used to analyze unknown substances Substances absorb, reflect, or transmit various wavelengths of light. This property can be used to indentify or quantify unknown substances.

13 UV-Visible Spectrophotometry
The absorption of UV or visible light can be used to indentify or quantify an unknown substance Identification is not exact; other substances can have similar absorption spectra

14 UV-Visible Spectrophotometry

15 Infrared Spectrophotometry
Unknown substances can be analyzed by measuring the absorption of infrared light. The absorption pattern is much more complex than UV. Substances can be specifically identified by their IR spectrum (like a fingerprint)

16 Infrared Spectrophotometry

17 Mass Spectrometry Often used as a detector for Gas Chromatography
A substance is bombarded with high-energy electrons This causes the substance to ionize. The ions break up into smaller fragments. The fragments are separated by mass The fragmentation pattern is unique to each individual substance

18 Mass Spectroscopy


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