4 main uses of chromatography ?
Analyze – examine a mixture, its components, and their relations to one another
Identify – determine the identity of a mixture or components based on known components
Purify – separate components in order to isolate one of interest for further study
Quantify – determine the amount of the a mixture and/or the components present in the sample
what does mobile phase mean ?
the liquid or gas that flows through a stationary phase
how does chromatography work ?
Mobile phase is forced through a stationary phase held in a column or on
a solid surface
stationary phase should be inert
explain analyses interacting with the stationary phase ?
Those that interact greatly, appear to move more slowly. Those that interact
weakly, appear to move more quickly.
This allows for samples to be separated into their components.
what’s size exclusion chromatography ?
porous support separates solutes based on size / shape
what’s adsorption chromatography ?
solutes adsorb to a support surface
what’s partition chromatography ?
solutes partition into a non polar or polar coating
what’s affinity chromatography ?
solutes selectively bind to a biologically related ligand
what’s ion exchange chromatography ?
charged solutes bind to fixed charges
explain TLC ?
The sample is spotted directly onto the TLC as a Liquid (small volume, typically uL)
When the TLC plate is placed into solvent, it is drawn up via capillary action
The analyte competes for interaction with the stationary and mobile phase and therefore only travels up the plate a certain distance which can be measured
Advantages of TLC ?
- Relatively cheap
- Relatively simple
- Relatively quick (well, the interpretation anyway)
what else can TLC be used for ?
checking the purity of the substance
how to calculate Rf value ?
sample / solvent front
two most common types of column chromatography?
reversed phase
normal phase
what’s reversed phase ?
Stationary Phase - Non polar
Mobile Phase - Relatively polar (i.e.
mixture of solvent and water)
Interaction - Non polar molecules
interact more with the stationary phase
(VDW forces)
what’s normal phase ?
Stationary Phase - Polar
Mobile Phase - Relatively non polar
(i.e. organic solvent)
Interaction - Polar molecules interact
more with the stationary phase (dipole
forces, hydrogen bonding etc)
how do you know if a sample is separated if its colourless or similar in colour ?
use mass spectrometry
what’s HPLC ?
HIGH PERFORMANCE LIQUID CHROMATOGRAPHY
Works under the same principle as column chromatography but under a
very high pressure
what’s the purpose of the pump in HPLC ?
This forces the analyte mixture through a column, increasing speed but also allowing for better separation with smaller columns.
what’s the purpose of the injector in HPLC ?
Capable of injecting small volumes reproducibly (important for quantitation)
what’s the purpose of the analytical column in HPLC ?
This can have a number of different types of stationary phase (most
commonly reversed phase) but also normal phase. For reversed phase, there are different polarities
what’s the purpose of the detector in HPLC ?
Shows the time and amount of substance being eluted
three types of brand broadening ?
eddy diffusion
longitudinal diffusion
mass transfer diffusion
what’s eddy diffusion ?
Sample molecules moving through the column do not all take the same
path.
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Intro states of matter23
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Atoms upward15
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periodic table trends22
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Bonding21
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Mole Calculations, Dilutions, Ph, Conc17
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mass spectrometry22
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chromatography28
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intro to organic chemistry23
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Organic Chemistry – Alcohols, Carbonyls & Reactions30
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NMR spectroscopy24
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spectroscopy30
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infrared spectroscopy8
