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FDSN 507 Midterm 2

Chromatography

Chromatography is used as a _____ technique. seperation
Define extraction. Transfer of solute from one liquid phase to another,
Name three different types of extractions. Batch, continuous, counter-current
Counter-current extraction is the basis for ____ chromatography. partition
Describe batch extraction. Solute is extracted with solvent by shaking it with a second, immiscible solvent.
T or F: At equilibirum, the partition coefficient (K) is constant. True
Define chromatography. Separation techniques based on partitioning of a solute between mobile phase and stationary phase.
The relative interaction of solute with mobile and stationary phases is described by _____. partition coefficient.
T or F: A gas can be in the stationary phase. False
Chromatography methods have retention which varies with ____ and _____. molecular size, polarity
____ chromatography is used to separate thermally stable volatiles. GC
What three characteristics are volatiles separated by in GC? Boiling point, molecular size, polarity
Supercritical fluids have high ____ and low ____. diffusivity, viscosity
What is supercritical fluid chromatography used to separate? Non-polar and non-volatile compounds
The stationary phase for supercritical fluid chromatography is similar to _____; equipment is similar to ____ and detector is similar to ____. HPLC, HPLC, GC
Describe liquid chromatography. Involves a liquid mobile phase and a solid or liquid stationary phase.
Components of a mixture in paper chromatography are characterized by their _____. relative mobility
Define Rf value. Distance moved by the component/distance moved by solvent
Which Rf value will be higher, that of a more polar or less polar compound? Polar
What are the advantages to TLC over paper chromatography? Better resolution, faster, more reproducible.
What technique would you use to screen corn and peanuts for mycotoxins before processing? TLC
What three ways can separation occur in TLC? Adsorptive, partition, ion exchange
What thee ways can TLC be visualized? Colorimetrically, emitted radiation, radioactivity
A ____ can be used to quantitatively measure TLC. densitometer
In column chromatography, the mobile phase is ____ while the stationary phase is ____. liquid, solid
Define isocraticin column chromatography. Constant mobile phase composition.
Define gradient in column chromatography. Changing nature of mobile phase.
How are solutes separated in column chromatography? Based on strength or interaction with stationary phase.
A detector response for column chromatography is recorded as a _____. chromatogram
T or F: The adsorption coefficient is constant in comparison to partition coefficient. False
T or F: More polar solutes elute first in adsorption chromatography. False
What is the principle of adsorption chromatography? Separates non polar compounds based on the number and type of functional groups present.
What technique would you use to separate fat-soluble pigments and vitamins? Adsorption chromatography
In partition (liquid/liquid) chromatography, when the most polar phase is held stationary this is called stationary _____ phase chromatography. normal
In partition (liquid/liquid) chromatography, when the least polar phase is held stationary this is called stationary _____ phase chromatography. reversed
What is the disadvantage to partition chromatography? The liquid stationary phase is often stripped off (overcome with bonded supports).
What three intermolecular interactions are responsible for adsorption chromatography? Electrostatic forces, hydrogen bonds, hydrophobic interaction
Ion exchange chromatography involved ____ interactions between the solute and the stationary phase. electrostatic
What are the four types of ion-exchangers? cation (binds anions), anion (binds cations), polystyrene, polysaccharide
How can solutes bound to an ion-exchanger be eluted? Change the mobile phase pH, increase ionic strength of mobile phase.
Name three items which can be separated using ion-exchange chromatography. Amino acids, sugars, proteins, drugs, fatty acids
Describe solid-liquid chromatography. Separation occurs based on interaction between a solute and an immobilized ligand.
A ____ holds the ligand away from the support surface in affinity chromatography. spacer arm
T or F: The ideal stationary phase in affinity chromatography does not absorb anything. True
What are three non-specific elution methods for affinity chromatography? Changing pH, ionic strength, temperture
What is affinity chromatography used to separate? enzymes, glycoproteins
What are the four types of interactions present in affinity chromatography? Hydrophobic, electrostatic, hydrogen bonding, van der waals
T or F: Large molecules move fastest in size-exclusion chromatogrpahy. True
What type of chromatography would be used to separate proteins? Size-exclusion
Define void volume. The volume of the mobile phase in a column.
Define elution volume. The volume required to elute a certain solute.
What are the four types of interactions present in size-exclusion chromatography? Hydrophobic, electrostatic, hydrogen bonding, covalent bonding
What four things must be considered in deciding on a separation technique? Stationary phase, mobile phase, elution conditions, detection method
What three characteristics define a chromatographic peak? Retention time, peak width, peak height
Resolution is a function of ____, _____, and _____. efficiency, selectivity, capacity
The number of theoretical plates is generally proportional to ______ in chromatographic resolution. column length
How are chromatographic peaks qualitatively analyzed? Compare retention time to standards under identical conditions to identify unknown compounds.
How are chromatographic peaks quantitatively analyzed? External and internal standards.
Created by: goberoi