30 Questions
What is the stationary phase in planar chromatography placed on?
A plane surface
In which technique did Mikhail Tswett introduce column chromatography?
Paper chromatography
Which type of stationary phase is best suited for non-polar analytes?
Non-polar stationary phases
What is the basis of all chromatographic methods according to the text?
The distribution of a component between two immiscible phases
In planar chromatography, how does the mobile phase move through the stationary phase?
By capillary action or under the influence of gravity
What did Mikhail Tswett separate using column chromatography?
Plant pigments such as chlorophylls and xanthophylls
What is the definition of the distribution coefficient DA?
The ratio of the concentration of a substance between mobile and stationary phases
Which parameter is sometimes referred to as dead time in chromatography?
tM
What is the significance of substances with high distribution coefficient DA?
They are retained more strongly by the stationary phase
Which time is defined as the time for solutes not to move along the column?
tS
What does the hold-up time tM represent in chromatography?
Time for non-retained analytes to move
How is the distribution coefficient DA related to substance retention in chromatography?
High DA leads to strong retention by the stationary phase
In ion-exchange chromatography, what is covalently attached to the stationary solid phase?
Anion or cation
What is the mobile phase in partition chromatography?
Gas
Which chromatography technique separates molecules by size?
Molecular Exclusion Chromatography
What happens to solute molecules in a chromatographic column as the mobile phase moves?
They separate and become distributed between phases
What is the purpose of retention parameters in chromatographic methods?
To maintain a dynamic equilibrium for analytes
What is typically the inside of the silica chromatography column in gas chromatography?
High-boiling liquid
What did Van Deemter propose in 1956?
An equation describing factors affecting band broadening in chromatographic separation.
What does the Van Deemter equation describe?
The factors affecting band broadening in chromatographic separation.
What does Term A in the Van Deemter equation describe?
Eddy diffusion, also known as the packing factor.
Why do non-retained solutes face multiple pathways during travel via the column?
As a result of facing particles of the stationary phase and moving around them.
What is one reason for peak broadening in chromatography?
The always-flowing mobile phase in a chromatographic column.
What is Eddy diffusion, also known as?
Packing factor
What is the term related to resistance to mass transfer in the mobile phase?
Term C: Resistance to mass transfer
What represents a function of the retention factor in Equation 2.14?
f (k´) is a constant
Which term emanates from mass transfer in the mobile phase?
Cu
What type of diffusion describes the transfer process between the mobile and stationary phases?
Longitudinal diffusion
What does Term A, Eddy diffusion, refer to in chromatography?
Flow direction
In the context of chromatography, what does Term B represent?
Longitudinal diffusion
Learn about planar chromatography where the stationary phase is on a flat surface, and column chromatography where the stationary phase is in a narrow tube. Discover methods like paper chromatography, thin layer chromatography (TLC), high-performance liquid chromatography (HPLC), and gas chromatography (GC).
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