Chromatography is a laboratory technique used to separate mixtures of compounds into their individual components based on how they interact with different substances. It works by taking advantage of differences in how molecules move through stationary and mobile phases. The key principles are that separation is achieved as compounds differentially interact and partition between phases based on properties like polarity, size, and solubility. Chromatography has many applications and is widely used in fields like industrial analysis, medicine, food testing, and environmental science.
2. Chromatography
Definition
Chromatography is: a laboratory technique
used to separate mixtures of compounds into
their individual components based on their
ability to move through different media when
exposed to certain solvents.
3. Introduction
( Chromatography )
Chromatography is an incredibly valuable
tool for research and development of
chemicals, pharmaceuticals and many other
industries.
Chromatography is a form of physical
separation technique used to separate mixtures
of compounds into their individual
components.
It works by taking advantage of differences in
the rates at which molecules move through
different media when a force is applied.
Chromatography has found applications in
many fields, including industrial,
environmental and biomedical analyses
4. Principles
1. Separation is achieved by the differential interactions of a sample mixture with the
stationary phase and mobile phase in chromatography.
2. The ability of a given compound to partition between different phases is determined by its
affinity to each phase, which can be affected by the polarity, size, shape and solubility of the
compound.
3.In liquid chromatography, retention time is an important factor that affects separations. It is
determined by the amount of sample adsorbed to the surface of the stationary phase compared to
that of the mobile phase, or “residence time” in the column.
4. Different detectors are used for different applications. Mass spectrometer (MS) detectors are
commonly used for qualitative analysis and identification purposes, while other detectors such as
ultraviolet-visible (UV-Vis) absorbance detector and refractive index (RI) detector are used for
quantification purpose in HPLC techniques.
5. History
The method was first
named "chromatography"
in 1906 by a German
chemist, Richard
Willstatter as he conducted
experiments to identify the
chemical compounds of
Chlorophyll.
In the early 1920s, van
Deemter and his
collaborators saw
chromatography as an
opportunity to use gas
phase molecules as
mobile phases, rather
than liquids.
In 1930, Archer J.P.
Martin received a
Nobel Prize for
developing paper
chromatography and
partition
chromatography.
6. Separations in TLC involve distributing a mixture of two
or more substances between a stationary phase and a
mobile phase.
The stationary phase:
is a thin layer of adsorbent (usually silica gel or alumina)
coated on a plate.
The mobile phase:
is a developing liquid which travels up the stationary
phase, carrying the samples with it.
Components of the samples will separate on the
stationary phase according to
how much they adsorb on the stationary phase versus
how much they dissolve in the mobile phase.
7. According to mobile phase:
1- Liquid chromatography: mobile phase is a liquid. (LLC, LSC).
Classification of chromatography
8. According to mobile phase:
2- Gas chromatography : mobile phase is a gas. (GSC, GLC).
Classification of chromatography
9. According to the packing of the stationary phase:
Classification of chromatography
1- Thin layer chromatography (TLC):
the stationary phase is a thin layer
supported on glass, plastic or aluminum
plates.
10. 1-Thin layer chromatography (TLC)
is a method for identifying substances and
testing the purity of compounds.
TLC is a useful technique because it is
relatively quick and requires small
quantities of material.
11. According to the packing of the stationary phase:
Classification of chromatography
2- Paper chromatography (PC): the
stationary phase is a thin film of liquid
supported on an inert support.
12. 2-Paper Chromatography
A method of partition chromatography using filter
paper strips as carrier or inert support.
The factor governing separation of mixtures of solutes
on filter paper is the partition between two
immiscible phases.
One is usually water adsorbed on cellulose fibres in
the paper (stationary phase).
The second is the organic solvent flows past the
sample on the paper (stationary phase).
13. According to the packing of the stationary phase:
Classification of chromatography
3- Column chromatography (CC): stationary
phase is packed in a glass column.
15. According to the force of separation:
Classification of chromatography
2-Affinity chromatography.
1-Adsorption chromatography.
Ion exchange chromatography
16. According to the force of separation:
Classification of chromatography
3-Partition chromatography. 4-Gel filtration chromatography.
17. According to the force of separation:
Classification of chromatography
5-Ion exchange chromatography
18. Purpose and uses
Is a technique used to separate
and identify the components of a
mixture.
Works by allowing the molecules present in the
mixture to distribute themselves between a
stationary and a mobile medium.
Molecules that spend most of their
time in the mobile phase are carried
along faster.
19. Conclusion
In conclusion:
• chromatography is a powerful and important tool in the field of analytical
chemistry
• It offers high resolution separation, can be used to purify compounds
and it is relatively easy and cheap to use.
• Its applications are found in many areas of research including medicine,
food analysis, materials science and environmental studies, among
others.
• Chromatography is undoubtedly one of the most widely used
techniques in chemical analysis.
21. References
1. Principles of chromatography | Stationary phase (article) | Khan Academy
2. https://www.khanacademy.org/science/class-11-chemistry-
india/xfbb6cb8fc2bd00c8:in-in-organic-chemistry-some-basic-principles-
and-techniques/xfbb6cb8fc2bd00c8:in-in-methods-of-purification-of-
organic-compounds/v/simple-and-fractional-distillations
3. Chromatography | Definition, Types, & Facts | Britannica
4. What is Chromatography and How Does It Work? (thermofisher.com)
5. Chromatography - an overview | ScienceDirect Topics
6. Chromatography - Chemistry LibreTexts