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Chem 194 - Analytical Chemistry C3 > Ch 34 Miscellaneous Separation Method > Flashcards

Ch 34 Miscellaneous Separation Method Flashcards

1
Q

The physical state of a substance held/ heated above its critical temperature

A

Supercritical fluid

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2
Q

Is the temperature above which a substance cannot be liquified

A

Critical temperature

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2
Q

Acts as the mobile phase in supercritical fluid chromatography and are able to dissolve large nonvolatile molecules

A

Supercritical fluid

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3
Q

The density of a supercritical fluid is ___ to ____ times that of its gaseous state

A

200 to 400

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3
Q

The pumping system in SFC that keeps the fluid in liquid state

A

Chilled pump head

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4
Q

The effects of pressure to the density of the supercritical fluids

A

Directly proportional

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5
Q

The most widely used mobile phase for supercritical fluid chromatography

A

CO2

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6
Q

Give the planar chromatographic techniques

A

Thin-layer Chrom
Paper Chrom
Electrochrom

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6
Q

Named the different detectors than can be used in SFC

A

Flame ionization detector
UV-visible absorption detectors
Light scattering detectors
Mass Spectrometry (Hyphenation)
Tandem mass spec

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7
Q

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

A

Thin-layer chrom

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7
Q

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

A

Planar chrom

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8
Q

Commercial plates used in TLC that have thicker layers of 200 to 250 μm, particle size of >20 μm

A

Conventional plates

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8
Q

Commercial plates used in TLC that have thicker layers of 100 μm, particle size of <5 μm

A

High-performance plates

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9
Q

The most critical aspect of TLC where the sample is applied as a spot 1 to 2 cm from the edge of the plate

A

Sample application

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9
Q

Increases the precision and accuracy of sample application

A

Mechanical dispenser

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10
Q

The process by which a sample is carried through the stationary phase by a mobile phase. Analogous to elution in liquid chromatography

A

Plate development

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11
Q

The process of locating analytes on a thin-layer plate is often termed as

A

Visualization

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11
Q

Two common methods in locating the analytes on the plate

A
  1. Spraying iodine or sulfuric acid solution
  2. Incorporation of fluorescent material to the stationary phase
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12
Q

Samples are placed on both ends of the plate and developed towards the middle, thus doubling the number of samples

A

Horizontal-flow developing chamber

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13
Q

Two types of developing chamber

A

Ascending-flow
Horizontal-flow

13
Q

Separation of analytes that uses a stationary phase from a highly purified cellulose with close control over porosity or thickness

A

Paper chrom

13
Q

The separation method based on the differential rates of migration of charged species in an applied electric field

A

Electrophoresis

14
Q

Have a unique ability to separate charged molecules of interest

A

Electrophoresis

15
Q

An electrophoresis that is carried out in columns and separate micro amounts of sample in fused-silica capillary tubes

A

Capillary Electrophoresis

16
Q

Enumerate the steps on the instrumentation of TLC

A

Preparation of TLC plates
Sample Application
Plate development
Locating analytes on the plate

17
Q

Dictate the instrumentation of Capillary electrophoresis

A
  • 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
18
Q

The flow of the solvent as it migrates towards the cathode as the voltage is applied

A

Electroosmotic flow

19
Q

A record or chart produced when electrophoresis is used in an analytical technique,

A

Electropherogram

20
Q

The ratio of the migration rate of an ion to the applied electric field

A

Electrophoretic mobility

21
Q

Formula for the migration rate of ion in an electric field

A

v = μc x E
v = μc x V/L

22
Q

Capillary electrophoretic separations are performed in several ways called

A

modes

23
Q

types of modes in electrophoresis

A

Isoelectric focusing, isotachophoresis, capillary zone electrophoresis

24
Q

Is a hybrid of HPLC and capillary electrophoresis. It is capable to separate neutral species and provides highly efficient separation on microvolumes of sample

A

Capillary electrochromatography

25
Q

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

A

Critical Micelle Concentration

25
Q

This form in aqueous solution when the concentration of an ionic species having a long-chain hydrocarbon tail is increased above a certain level

A

Micelles

26
Q

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.

A

Packed Column Electrochromatography

27
Q

Capillary electrophoresis carried out in the presence of micelles is termed

A

Micellar electrokinetic capillary chromatography (MECC)

28
Q

The technique where surfactants are added to the operating buffer in amounts that exceeded the critical micelle concentration

A

Micellar electrokinetic capillary chromatography (MECC)

29
Q

Common surfactant used in MECC

A

SDS or Sodium Dodecyl Sulfate

30
Q

A moving phase that acts as a stationary phase (e.g., the micelles in MEKC)

A

Pseodustationary phase

31
Q

A group of analytical techniques that separate and characterized dissolved or suspended materials such as polymers and colloids

A

Field-flow Fractionation (FFF)

32
Q

In FFF, the sample components migrate towards the ________

A

Accumulation wall

33
Q

The separation results in FFF that reveal the plot of detector response vs time is called

A

Fractogram

34
Q

What are the FFF methods

A

Sedimentation FFF, electrical FFF, thermal FFF, and flow FFF

35
Q

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

A

Sedimentation FFF

36
Q

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

A

Electrical FFF

37
Q

An FFF technique where a thermal field is applied perpendicular to the flow direction by forming a temperature gradient across the channel

A

Thermal FFF

38
Q

The most versatile of all FFF techniques where the external field is replaced by a slow cross flow of the carrier liquid

A

Flow FFF

Chem 194 - Analytical Chemistry C3 (27 decks)

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