Chapter 5

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Chapter 5 Organic Analysis
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Chemistry Review!!!

• Chem Vocab
• Matter has mass and takes up space
• Atom smallest unit of matter
• Periodic Table of Elements organizes elements
  (atoms) by atomic number
• Compound molecule containing different elements
• Phases of Matter solid, liquid, gas
• Sublimation solid to gas
• Organic must contain Carbon and Hydrogen
• Inorganic no C and H together

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Physical States of Matter
Definite Volume? Definite Shape? Speed Molecule Arrangement
Solid
Liquid
Gas
Yes
Yes
Slow
Yes
No
Medium
No
No
Fast
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Chemical Analysis of Evidence

• Most evidence received by crime labs requires
  identification of unknown organic compounds
• Drugs
• Ink
• Paint
• Fiber
• Explosives
• Analysis
• Qualitative identity of material
• Quantitative of components in mixture

ORGANIC ANALYSIS
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Analytical Techniques

• Spectrophotometry
• study of the absorption of light by chemical
  substances
• Chromatography
• separating components of a mixture
• relative of each component
• Mass spectrometry
• the determination of the molar mass of a
  substance
• Identity of components

ORGANIC ANALYSIS
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Chromatography
ORGANIC ANALYSIS
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The Basics
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The Basics

• Types
• Paper Chromatography
• Thin-Layer Chromatography
• High Performance Liquid Chromatography
• Gas Chromatography
• Two phases
• Stationary phase adsorbs the components of a
  mixture.
• Mobile phase sweeps the sample over the
  stationary phase.

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The Basics
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The Basics
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The Basics

• Components measured at end of stationary phase.
• Result - chromatogram
• Chromatography is non-destructive
• Different compound different speed

ORGANIC ANALYSIS
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Paper Chromatography

• Stationary phase strip of paper
• Mobile phase liquid solvent
• Sample is spotted onto the paper
• Capillary action moves solvent
• Components separate as spots
• Rf value dist. of component / dist. of solvent
• Often used for ink analysis

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Thin Layer Chromatography

• Stationary a thin layer coating on a sheet of
  plastic or glass
• Adsorbant Al2O3 (alumina) or SiO2 (silica)
• Mobile a liquid solvent
• Capillary Action
• Visualized by UV or reagent spray
• Rf is calculated.

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Toxi-Lab Drug Detection System
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Toxi-Lab Drug Detection System
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Toxi-Lab Drug Detection System
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High-Performance Liquid Chromatography (HPLC)

• Stationary column w/ solid particles
• Mobile liquid
• Liquid carries sample, components are slowed.
• Advantage of HPLC room temperature.
• Explosives analysis

ORGANIC ANALYSIS
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HPLC Instrument
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Gas Chromatography (GC)
ORGANIC ANALYSIS
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Gas Chromatography (GC)

• Materials heated to a gas and flow through the GC
  column.
• Mobile phase carrier gas helium or nitrogen.
• Stationary phase thin film of liquid.
• Mixture emerges separated into its components.

ORGANIC ANALYSIS
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Gas Chromatography (GC)
Figure 54  In this illustration of
chromatography, the molecules represented by the
blue balls have a greater affinity for the upper
phase and hence will be pushed along at a faster
rate by the moving air. Eventually, the two sets
of molecules will separate from each other,
completing the chromatographic process.
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Gas Chromatography (GC)
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Schematic of a GC
The sample is separated in the column, and the
carrier gas and separated components emerge from
the column and enter the detector (5). Signals
developed by the detector activate the recorder
(7), which makes a permanent record of the
separation by tracing a series of peaks on the
chromatograph (8). The time of elution identifies
the component present, and the peak area
identifies the concentration. Courtesy Varian
Inc., Palo Alto, Calif.
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GC Columns
A capillary column
A packed column
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GC Retention Time
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GC Analysis of Drugs
Figure 56  (a) An unknown mixture of
barbiturates is identified by comparing its
retention times to (b), a known mixture of
barbiturates. Courtesy Varian Inc., Palo Alto,
Calif.
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Mass Spectrometry and Infrared Spectrophotmetry
ORGANIC ANALYSIS
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Mass Spectrometry

• Beam of high-energy electrons collide with a
  material.
• Produces positive ions
• Separate according to mass
• No two substances produce the same separation
  pattern.

ORGANIC ANALYSIS
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Mass Spectrometry
Figure 521  (a) Mass spectrum of heroin. (b)
Mass spectrum of cocaine.
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Mass Spectrometer (MS)
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GC/MS
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GC/MS

• Gas chromatography separation
• Mass spectrometry - identification

ORGANIC ANALYSIS
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GC/MS
Figure 520  How GC/MS works. Left to right, the
sample is separated into its components by the
gas chromatograph, and then the components are
ionized and identified by characteristic
fragmentation patterns of the spectra produced by
the mass spectrometer. Courtesy Agilent
Technologies, Inc., Palo Alto, Calif.
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Infrared (IR) Spectrophotometry

• Absorption of IR light
• Vibrations of a bond in the molecule
• Different structures have different IR spectra
  (fingerprint of substance)

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IR Spectrophotometer
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IR Spectra of Drugs
The IR Spectrum of an unknown is searched against
a database of drug samples to identify it.
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Gel Electrophoresis

• Analyzes differences in DNA
• DNA from different sources placed in gel
• Electric current moves DNA from (-) to ()
• Look for similar banding pattern

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Gel Electrophoresis