Chromatographic Techniques in Chemical Analysis

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What is chromatography used for in chemical analysis?

Chromatography is used to separate, identify, and quantify components in a mixture based on differential partitioning between stationary and mobile phases.

How does gas chromatography (GC) separate compounds?

GC separates compounds by volatilizing them and passing them through a column where they partition between a gaseous mobile phase and a liquid stationary phase.

What role does the stationary phase play in liquid chromatography (LC)?

In LC, the stationary phase interacts with sample components, exerting different affinities that affect separation during passage with a liquid mobile phase.

What is the principle of High-Performance Liquid Chromatography (HPLC)?

HPLC uses high pressure to push solvents and samples through a tightly packed column, providing efficient separation of components based on interactions with the stationary phase.

What factors influence retention time in chromatography?

Factors such as column temperature, mobile phase flow rate, stationary phase properties, and compound properties influence retention time in chromatography.

How does size-exclusion chromatography separate molecules?

Size-exclusion chromatography separates molecules based on their size, as larger molecules elute faster due to lower affinity for the porous stationary phase.

What types of detectors are used in GC?

Common GC detectors include Flame Ionization Detectors (FID), Thermal Conductivity Detectors (TCD), and Mass Spectrometers (MS).

Why is it important to use an inert carrier gas in GC?

An inert carrier gas prevents interactions with the sample and ensures reliable separation by eliminating unwanted reactions or interference.

How does reverse-phase chromatography differ from normal phase?

Reverse-phase chromatography uses a non-polar stationary phase and a polar mobile phase, opposite to normal phase's polar stationary and non-polar mobile phase configuration.

What is the function of a mobile phase in chromatography?

The mobile phase serves to transport analytes through the column, facilitating interaction with the stationary phase and separation based on affinity differences.

How is ion-exchange chromatography used to separate charged molecules?

Ion-exchange chromatography separates charged molecules by exploiting their affinity to oppositely charged stationary phase materials.

What is the purpose of gradient elution in liquid chromatography?

Gradient elution is used to optimize separation by gradually changing the mobile phase composition to increase resolution and reduce analysis time.

Why is TLC (Thin-Layer Chromatography) useful for quick analysis?

TLC is a simple, fast, and inexpensive method for initial sample analysis, providing qualitative data and aiding in monitoring synthesis or purity.

What are chiral stationary phases used for in chromatography?

Chiral stationary phases are used to separate enantiomers, compounds that are mirror images and require chiral binding sites for effective separation.

How does Flame Ionization Detection (FID) work in GC?

FID works by detecting ions formed from combustion of organic compounds in a hydrogen flame, providing a signal proportional to the number of carbon atoms.


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