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Organic Chemistry Year 2 > chromatography > Flashcards

Flashcards in chromatography Deck (15)
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1

mobile phase

carries the soluble components of the mixture

2

what relationship between a sample and the mobile phase makes the sample move faster

more soluble components
components with more affinity to the solvent move faster

3

stationary phase

holds back components of the mixture that are attracted to it

4

relationship between a sample and the stationary phase that makes the sample move slower

more affinity for the stationary phase means that a component moves slower, often attracted by hydrogen bonding

5

how are substances separated by chromatography

if suitable stationary/mobile phases are chosen, the balance between affinity for the mobile phase and affinity for the stationary phase is different for each component of the mixture. thus, they move at different rates and are separated over time

6

advantages of TLC over paper chromatography

runs faster
smaller amounts of a mixture can be separated
TLC plates are more robust that paper

7

Rf

a measure of the rate of movement of a component through the chromatography apparatus
a ratio between the rate of movement of the solvent and that component

8

column chromatography

column packed with silica, alumina or resin has solvent run through it

9

mobile phase in CC

solvent added at the top and runs down the column

10

advantages of CC

more than one eluent can be used
fairly large amounts can be separated

11

stationary phase in gas-liquid chromatography

powder, coated in oil. packed into a long, thin, capillary tube. coiled and placed in an oven the temperature of which can vary

12

mobile phase in GLC

carrier gas, inert
N2
He

13

advantages of GLC

very sensitive

14

GLC uses

test athletes

15

how does GCMS work

GC is run, retention time is recorded, then mixture is run through a mass spectrometer
fragmentation pattern/molecular ion peak confirms identity