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21 Cards in this Set
- Front
- Back
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Temperature programming |
Changing temperature during separation to separate compounds with a wide range of boiling points or polarities |
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Adsorption chromatography |
Stationary: solid Mobile: liquid or gaseous Solute is adsorbed on the surface of the solid particle of stationary phase |
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Partition chromatography |
Stationary: thin liquid coated on a solid support Mobile: liquid Solute equilibriums between the stationary liquid and mobile phase |
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Ion-exchange chromatography |
Solutes attached to stationary phase by electrostatic forces Mobile: liquid Mobile anions held near cations that covalently attached to stationary phase |
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Molecular chromatography |
Separation by size Large molecules travel fastest Small molecules penetrate the pores of particles |
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Affinity chromatography |
Separation based on specific interaction between one kind of molecule in the complex mixture and molecules that are covalently attached to stationary phase |
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More theoretical plates |
More equilibration points = better separation = better resolution (narrow peaks) |
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Retention time |
Time it takes for a compound to get to detector |
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Adjusted retention time |
Gives a value relative to the solvent or carrier that is more reliable |
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Atomic spectroscopy |
Molecules are decomposed into atoms Concentration of atoms is measured by its interaction (absorption, emission) with a characteristic wavelength of radiation |
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Molecular spectroscopy |
Deals with interaction of intact molecules with radiation |
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Isosbestic point |
Indicate that one compound with a type of interaction with light transforms to another compound with a different type of interaction with light |
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Galvanic cell vs electrolytic cell |
Galvanic is spontaneous Electrolytic needs a voltage to move electrons |
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Monochromator |
Select a narrow wavelength range of light from the light source to pass through sample |
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Hollow cathode lamp |
To produce narrow lines of the correct frequency for atomic absorption It’s cathode is made of the element we want to observe |
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Longitudinal diffusion |
The longer time a solute stays on the column = longer time it has for diffusion = peak width is broaden = worse resolution |
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Finite rate of mass transfer |
Solutes require finite time to equilibrate between 2 phases If equilibration is slow, solute in stationary phase will lag behind that in mobile phase = broadening |
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Multiple paths |
In a packed column, solutes can migrate through many paths Straight route comes off first More winding routes come out later and cause brladejng |
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Benefit of open column comparing to packer column |
Open path = no multiple pathways More plates / smaller plate heights Less resistant to flow => column can be longer |
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Boiling point and flow rate |
Lower boiling point come off first Lower boiling point but interacting with column will come off later |
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Flame ionization detector |
Sensitive to hydrocarbon Insensitive to non-hydrocarbon Carrier gas: N2 Equate is burned in a mixture of H2 and air. The carbon atoms, except carbonyl and carbonyl, produce CH radicals, which then produce CHO+ ions. The flow of ions and electrons in the electrodes create detector signal |
