5 Ways to Make Ion Exchange Chromatography a More Approachable Topic for Students

Introduction: Ion exchange chromatography

Chromatography is a process of separating the mixture of substances for qualitative and quantitative analysis. Liquid chromatography is a kind of chromatography that consists of mobile and stationary phases. The mobile phase is always liquid, while the stationary phase either be liquid or solid. Liquid chromatography has further types and ion exchange chromatography is one of them.

Ion exchange chromatography is a process that separates the ions and polar molecules on the basis of the charge. The charge biological molecules such as proteins, amino acids, peptides, and nucleotides can be separated through ion exchange chromatography. For example, proteins contain amino acids of both positive and negative charge.

In Ion exchange chromatography, cationic exchangers and anionic exchangers are used. Cationic exchangers contain a negative charge and attract a positive charge. Anionic exchangers have a positive charge stationary phase and attract the negative charge.

Generally, it is performed in the form of column chromatography. The crude biological sample containing charge is sued as liquid phase. This sample is passed through the column and charged molecules will be attached to the opposite charge stationary phase.

There are some aspects of ion exchange chromatography that might be confusing for learners. At Labster, we provide you with the main reasons that make this topic challenging for students. Then, there are five ways that can be helpful for learning. At the end of this topic, we will convince you why a virtual lab is important to teach students.

Figure: Process of ion exchange chromatography from Labster’s Theory

Why ion exchange chromatography can be tricky to learn

There are 3 main reasons why ion exchange chromatography is a tough topic even for hardworking students.

1. It feels abstract

Some abstract terms are used in ion exchange chromatography. The cations, anions, neutral charge, and buffer gradient are abstract terms that students cannot see with their naked eyes. They need to imagine these terms in their minds, that sometimes difficult for students to learn.

2. It’s complicated

In ion exchange chromatography, students need to learn the whole procedure step by step. If one of the steps gets wrong, the results will be changed. The apparatus used in this chromatography and the functions can be important to learn. The ion exchange chromatography is a complex course that can be tricky to learn from the theory. So, some students may feel that it is a complicated topic to remember.

3. The selection of resin may be confusing:

The resin acts as the medium that exchanges the ions. There are several resins available according to the separation of the substance. It is difficult to remember the name of the resin used for specific ion exchange chromatography. So, students may be confused about learning the resin names and their functions in ion exchange chromatography of the different substances.

5 ways to make ion exchange chromatography a more approachable topic to understand

Since you know the difficulties that students face during learning ion exchange chromatography, there are some ways that make this topic more interesting and exciting for students.

1. Talk about the people behind the science

It is important for learners to know the people’s efforts behind this course of ion exchange chromatography. The ion exchange chromatography method began in 1850. Sir H.S.M Thomson and J.T. Way introduced the process of ion exchange chromatography. They wrote a paper and the topic name was “On the Power of Soils to Absorbs Manure”. J.T. Way used a box with a hole in the bottom. He filled the box with soil and added some solution of potassium chloride. After that, he collected the liquid from the bottom of the box. He named this process “base exchange” which changed in 1940. Since that time, this process is known as ion exchange chromatography. Moreover, in 1947, Spedding and Powell worked on ion exchange chromatography to separate rare earth. Ion exchange chromatography is used as an effective technique in many fields of chemistry, including distillation, filtration, and absorption.

2. Explain the key steps of the process:

Students should learn about the basic steps to separate the substances on the basis of their charge by using ion exchange chromatography. The instruments are a column, suppressor, pump, injector, and recorder. 

Column: A column is selected to separate the mixture in ion exchange chromatography. In laboratories, the column used in chromatography is made of glass. But stainless steel or polymers columns are used in industries. The column consists of a diameter from 2 mm to 5 cm and the length can vary from 3 cm to 50 cm. Additionally, a guard column is also used inside the chromatographic column.

Suppressor: It is used to diminish the background conductivity of the chemicals in the procedure. It helps to improve the conductive measurement from the ion exchange column.

Pump: The pump is useful to provide a constant low to the eluent in this process. The pump is considered an important instrument in the process of ion exchange chromatography.

Injector: Injector valve is the best way to introduce the sample into the column for the separation of ions. The liquid samples can enter the injector directly. But the solid sample needs to dissolve in the solvent and then add it into the injector. 

For the purification of the protein, the steps are following: 

1. In the chromatographic column, an impure protein sample is added to a certain pH.

2. The charged protein molecules can attach with the negative charge resin molecules.

3. A salt gradient is used that separates protein from resin.

4. If a small amount of salt gradient is used then few protein molecules can be separated from the resin. For more separation, more salt gradient should be added. 

Several factors can affect ion exchange chromatography. For instance, the volume of the salt gradient depends upon the size particle. If elution is required for the large particles, the high volume of the salt gradient can be used for separation.  

The pH scale is another factor that is used to separate protein by isoelectric point. The isoelectric point is a point at which amino acids contain a natural charge and do not migrate to the positive or negative side in an electric field. According to this factor, a decreasing pH gradient is responsible for the separation of protein from the anion exchange resin. While an increasing pH gradient is effective for the separation of protein from the cation exchange resin.

Figure: An image of an injector of ion exchange chromatography from the Labster’s virtual laboratory.

3. Use color diagrams

Students will enjoy learning ion exchange chromatography when they see color diagrams. The diverse colors make it easier to differentiate the separation between the substances. To learn ion exchange chromatography, students need to know about the shape of the column, injector, column stand, sample container, and sample color. When they see color diagrams of the apparatus used in ion exchange chromatography, it enhances their interest and they easily remember the experiment. 

Figure: An image of apparatus of ion exchange chromatography from the Labster’s visual simulation. 

4. Learn about applications of ion exchange chromatography:

Ion exchange chromatography is a popular method to separate substances containing positive and negative charges. Mostly, it is used for the purification, and separation of proteins, and metals, proteins, and softening of water. The common applications of ion exchange chromatography are the following:

In the field of medicine, ion exchange chromatography is used to separate the blood components of the sample. This technique is effective in removing sodium from the GIT (gastrointestinal tract) to treat edema. For that, the carboxylic resin is orally given to the patient. Ion exchange chromatography is also used to treat stomach ulcers.

In industries, ion exchange chromatography is used to check the qualities and impurities of chemical substances. Hard water is the result of the presence of magnesium and calcium ions. Hard water makes insoluble precipitation with soaps. To treat hard water, it is passed through the chromatographic column that contains sodium ions. After some time, the calcium and magnesium separate from the water. Then, a concentration of salt is added to the column after collecting the water from the column. It helps to tightly hold the calcium and magnesium ions.

Additionally, chelating resins are useful for collecting trace metals from seawater. Ion exchange chromatography is an effective way to analyze the trace elements and lunar rock on the earth.

5. Virtual lab simulation

Virtual lab simulation is an advanced way to teach students about ion exchange chromatography. At Labster’s, we provide you with a 3D laboratory simulation that contains gamification elements to deliver the topic effectively.

Labster’s ion exchange chromatography simulation helps provide knowledge about the apparatus, performed liquid chromatography, and whole detail about the substance separation on the basis of the size. A virtual lab can be effective to explain topics like ion exchange chromatography to students as well as beneficial for teachers to convey the concept.

Learn more about ion exchange chromatography simulation here, or get in touch to find out how you can start using a virtual lab with your students.