The key difference between distillation and chromatography is that distillation is used to separate components in volatile liquids, whereas chromatography can be used to separate components that are usually non-volatile.
Both distillation and chromatography are important methods of separation of different components in an analyte mixture.
CONTENTS
1. Overview and Key Difference
2. What is Distillation
3. What is Chromatography
4. Distillation vs Chromatography in Tabular Form
5. Summary – Distillation vs Chromatography
What is Distillation?
Distillation is the selective boiling and subsequent condensation of a component in a liquid mixture. Therefore, it is a separation technique useful in either increasing the concentration of a certain component in a mixture or obtaining pure components from the mixture. This process gives the difference in the boiling points of the components in the liquid mixture by forcing one of these components into a gaseous state. However, distillation is not a chemical reaction; we can consider it a technique of separation.
Figure 01: Distillation
There are different types of distillation processes, such as simple distillation, fractional distillation, steam distillation, vacuum distillation, short path distillation, and zone distillation.
In a laboratory, we can perform distillation using batches of the liquid mixture, while in industrial applications, a continuous distillation process is usually performed to obtain and maintain the required composition of the desired component.
However, it is impossible to completely separate a component from a mixture and purify it. This is because, at the boiling point of a mixture of liquids, all of its volatile constituents boil at the same time. Here, the composition of a particular constituent in the resulting vapor mixture depends on the contribution of that component to the total vapor pressure of the mixture. Therefore, we can concentrate compounds having a higher partial pressure in the vapor, but compounds with lower partial pressure are concentrated in the liquid.
What is Chromatography?
Chromatography is an analytical technique useful in separating components in a mixture. In this technique, the analyte sample is combined with a liquid or gaseous mobile phase. This mobile phase is passed through a stationary phase. Generally, one of the two phases is hydrophilic, and the other is lipophilic. The components in the analyte mixture can interact with the mobile and stationary phases differently. The polarity of these phases and the components in the mixture play a huge role in this method. The components may spend more or less time with each phase, which causes greater or lesser retardant by these phases. Using these interactions, we can separate the particles in the mixture.
The retention time is the time each sample component takes to elute through the stationary phase. When the components pass through the detector, a signal is recorded and plotted in the form of a chromatogram.
Figure 02: Column Chromatography
There are four major types of chromatographic techniques: adsorption chromatography, TLC or thin layer chromatography, column chromatography, and partition chromatography. In adsorption chromatography, different compounds tend to be adsorbed on the adsorbent in different degrees, depending on the absorptivity of the analyte component. Thin layer chromatography is a simple-to-carry-out method in which we use a glass plate coated with a very thin layer of adsorbent (e.g., silica gel), which is partially immersed in the mobile phase for the separation. Column chromatography uses a column packed with the stationary phase, and the analyte is passed through this column along with the mobile phase. Partition chromatography, on the other hand, uses a continuous differential partitioning of components of a mixture into a stationary phase and the mobile phase.
What is the Difference Between Distillation and Chromatography?
Distillation and chromatography are important analytical techniques. The key difference between distillation and chromatography is that distillation is used to separate components in volatile liquids, whereas chromatography can be used to separate components that are usually non-volatile.
The following table summarizes the difference between distillation and chromatography.
Summary – Distillation vs Chromatography
Distillation is the selective boiling and subsequent condensation of a component in a liquid mixture. Chromatography is an analytical technique useful in separating components in a mixture. The key difference between distillation and chromatography is that distillation is used to separate components in volatile liquids, whereas chromatography can be used to separate components that are usually non-volatile.
Reference:
1. “Distillation – Definition, Detailed Process, Types, Uses.” BYJUS.
Image Courtesy:
1. “BatchDistill” By User A1 at English Wikipedia – Transferred from en.wikipedia to Commons by IngerAlHaosului using CommonsHelper. (FAL) via Commons Wikimedia
2. “Coloured column chromatography (16743431852)” By Максим Фомич – Coloured column chromatography (CC BY 2.0) via Commons Wikimedia