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19 Cards in this Set
- Front
- Back
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What is chromatography?
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An analytical technique that separates components in a mixture between a mobile phase and a stationary phase
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What state can the mobile phase be?
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Liquid or gas
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When is the stationary phase solid?
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TLC
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When is the stationary phase liquid or solid on a solid support?
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GC
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How does a solid stationary phase separate?
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By ADSORPTION
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How does a liquid stationary phase separate?
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By relative solubility
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What is the Rf value? (Calculation)
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distance moved by component/distance moved by solvent front
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Define 'Retention Time'
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In GC, it is the time for a component to pass from the COLUMN INLET to the DETECTOR
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What are the limitations of GC?
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Similar compounds often have similar retention times
Unknown compounds have no reference retention times for comparison |
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Mass spectroscopy can often be combined with which form of chromatography?
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Gas (To make GC-MS)
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Why is GC-MS used?
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To provide a far more powerful analytical tool than from chromatography alone
To generate mass spectra which can be analysed or compared with a spectral database by computer for positive identification of a component |
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What are some uses of GC-MS?
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Analysis - specifically forensics, environmental analysis, airport security and space probes.
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What does NMR involve?
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Interaction of materials with the low-energy radiowave region of the electromagnetic spectrum
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What can carbon-13 make predictions about? (2)
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The different types of carbon present, from chemical shift values
Possible structures for the molecule |
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What can HIGH RES proton NMR help to make predictions about? (4)
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The different types of proton present, from chem shift values
The relative numbers of each type of proton present from RELATIVE PEAK AREAS, using INTEGRATION TRACES or RATIO NUMBERS The number of NON-EQUIVALENT PROTONS adjacent to a given proton from the spin-spin splitting pattern, using the n + 1 rule Possible structures for the molecule |
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What is TMS used for?
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The standard for chemical shift measurements
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What kind of solvents are needed for NMR?
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Deuterated solvents - e.g. D₂O or CDCl₃
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What happens to O-H AND N-H peaks without deuterated solvents?
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They ar enot present
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NMR is also used in...
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MRI to obtain diagnostic information about internal structures in body scanners
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