Study Guide #5
Chromatography

Definition

A family of separation techniques based on competition between a                stationary phase and a mobile phase for the analyte

Definitions

Analyte - the mixture whose separation is being sought
Stationary phase - A solid or viscous liquid which does not move
Mobile phase - A liquid or gas which carries the analyte through the mobile phase

Gas Chromatography Applications

Most drugs
Fire residues
Blood alcohols

Chromatogram of Gasoline

Pyrolysis Gas Chromatography

Analyte is pyrolyzed in injector of GC
pyrolysates separated by GC
Used for inert polymers
        Paints
        Fibers
        Hairs
        Adhesives

Pyrolysis Wand

Pyrogram of Nylon

Gas Chromatography - Mass Spectrometry

Mass spectrometer is detector for GC
GS separates components of mixture.
Each component is sent to mass spectrometer

Mass Spectrometry

Mass spectrometer bombards analyte component with beam of electrons
Molecule breaks apart into stable, reproducible fragment ions by lose of electron
Pattern of fragments can ID the molecule
Base peak - most abundandt fragment
Parent peak - molecular ion
Diagram of GC-MS

Mass Spectrum of Cocaine

HPLC

Stationary phase may be solid or liquid coated spheres
Mobile phase is liquid or liquid solution
Usually run at room temperature
Can be isocratic or gradient
Can be used for quantitation
HPLC Diagram

Applications

Inks and dyes
Some drugs
Some explosive residues
Soils
TLC
Stationary phase is solid coated onto surface of glass
Mobile phase is liquid or liquid solution
Analyte is introduced as spot at bottom of TLC plate
Mobile phase carries up plate by capillary action
Detection by UV or color spray
Same applications as HPLC
Diagram of TLC Experiment

Electrophoresis

Similar to TLC
Stationary phase may be cellulose acetate, agarose or polyacrylamide
Mobile phase is buffered liquid solution
System subjected to strong electrical current which polarizes ends of stationary phase

Electrophoresis

Can separate closely related substances
Used for blood groups
Separates DNA fragments

Diagram of Electrophoresis
Apparatus

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