Ch 34 Miscellaneous Separation Method Flashcards
The physical state of a substance held/ heated above its critical temperature
Supercritical fluid
Is the temperature above which a substance cannot be liquified
Critical temperature
Acts as the mobile phase in supercritical fluid chromatography and are able to dissolve large nonvolatile molecules
Supercritical fluid
The density of a supercritical fluid is ___ to ____ times that of its gaseous state
200 to 400
The pumping system in SFC that keeps the fluid in liquid state
Chilled pump head
The effects of pressure to the density of the supercritical fluids
Directly proportional
The most widely used mobile phase for supercritical fluid chromatography
CO2
Give the planar chromatographic techniques
Thin-layer Chrom
Paper Chrom
Electrochrom
Named the different detectors than can be used in SFC
Flame ionization detector
UV-visible absorption detectors
Light scattering detectors
Mass Spectrometry (Hyphenation)
Tandem mass spec
Can be considered a form of liquid-solid chrom in which the stationary phase is a thin layer on the surface of a plate. The mobile phase is drawn by capillary action
Thin-layer chrom
This is a chromatographic technique where the mobile phase moves through the stationary phase by capillary action, sometimes assisted by gravity or an electrical potential
Planar chrom
Commercial plates used in TLC that have thicker layers of 200 to 250 μm, particle size of >20 μm
Conventional plates
Commercial plates used in TLC that have thicker layers of 100 μm, particle size of <5 μm
High-performance plates
The most critical aspect of TLC where the sample is applied as a spot 1 to 2 cm from the edge of the plate
Sample application
Increases the precision and accuracy of sample application
Mechanical dispenser
The process by which a sample is carried through the stationary phase by a mobile phase. Analogous to elution in liquid chromatography
Plate development
The process of locating analytes on a thin-layer plate is often termed as
Visualization
Two common methods in locating the analytes on the plate
- Spraying iodine or sulfuric acid solution
- Incorporation of fluorescent material to the stationary phase
Samples are placed on both ends of the plate and developed towards the middle, thus doubling the number of samples
Horizontal-flow developing chamber
Two types of developing chamber
Ascending-flow
Horizontal-flow
Separation of analytes that uses a stationary phase from a highly purified cellulose with close control over porosity or thickness
Paper chrom
The separation method based on the differential rates of migration of charged species in an applied electric field
Electrophoresis
Have a unique ability to separate charged molecules of interest
Electrophoresis
An electrophoresis that is carried out in columns and separate micro amounts of sample in fused-silica capillary tubes
Capillary Electrophoresis
Enumerate the steps on the instrumentation of TLC
Preparation of TLC plates
Sample Application
Plate development
Locating analytes on the plate
Dictate the instrumentation of Capillary electrophoresis
- Fuse-silica capillaries have two buffer reservoirs that hold platinum electrodes.
- The sample is introduced at one end and detection at the other end.
- Sample introduction is through electrokinetic or pressure injection
- Voltage is applied causing ionic migration and electroosmotic flow
- Detected
The flow of the solvent as it migrates towards the cathode as the voltage is applied
Electroosmotic flow
A record or chart produced when electrophoresis is used in an analytical technique,
Electropherogram
The ratio of the migration rate of an ion to the applied electric field
Electrophoretic mobility
Formula for the migration rate of ion in an electric field
v = μc x E
v = μc x V/L
Capillary electrophoretic separations are performed in several ways called
modes
types of modes in electrophoresis
Isoelectric focusing, isotachophoresis, capillary zone electrophoresis
Is a hybrid of HPLC and capillary electrophoresis. It is capable to separate neutral species and provides highly efficient separation on microvolumes of sample
Capillary electrochromatography
This is the level where the surfactant begins to form spherical aggregates made up to 40 to 100 ions with their hydrocarbon tails and their charged ends exposed to water in the outside
Critical Micelle Concentration
This form in aqueous solution when the concentration of an ionic species having a long-chain hydrocarbon tail is increased above a certain level
Micelles
The least mature of the various electroseparation techniques. A polar solvent is usually driven by electroosmotic flow through a capillary that is packed with a reversed-phase HPLC packing.
Packed Column Electrochromatography
Capillary electrophoresis carried out in the presence of micelles is termed
Micellar electrokinetic capillary chromatography (MECC)
The technique where surfactants are added to the operating buffer in amounts that exceeded the critical micelle concentration
Micellar electrokinetic capillary chromatography (MECC)
Common surfactant used in MECC
SDS or Sodium Dodecyl Sulfate
A moving phase that acts as a stationary phase (e.g., the micelles in MEKC)
Pseodustationary phase
A group of analytical techniques that separate and characterized dissolved or suspended materials such as polymers and colloids
Field-flow Fractionation (FFF)
In FFF, the sample components migrate towards the ________
Accumulation wall
The separation results in FFF that reveal the plot of detector response vs time is called
Fractogram
What are the FFF methods
Sedimentation FFF, electrical FFF, thermal FFF, and flow FFF
An FFF technique where the channel is coiled and made to fit inside a centrifuge basket wherein components that have higher mass and density are elute last and low-mass species are eluted first
Sedimentation FFF
An FFF technique where an electric field is applied perpendicular to the flow direction and thus, separates based on electrical charge. Species with higher charge are driven effectively towards the accumulation wall (retained the most), whereas lower charge species are eluted first
Electrical FFF
An FFF technique where a thermal field is applied perpendicular to the flow direction by forming a temperature gradient across the channel
Thermal FFF
The most versatile of all FFF techniques where the external field is replaced by a slow cross flow of the carrier liquid
Flow FFF
