The key difference between extraction and isolation is that extraction is a technique that helps to separate the desired compound from a mixture whereas isolation is a technique that helps to purify the extracted compound.
Most of us often assume that both extraction and isolation are the same. But, they are two different steps in separation processes. There is a distinct difference between extraction and isolation in terms of technique and end product.
CONTENTS
1. Overview and Key Difference
2. What is Extraction
3. What is Isolation
4. Side by Side Comparison – Extraction vs Isolation in Tabular Form
5. Summary
What is Extraction?
Extraction is the process of moving one or more compounds of interest (analytes) from their original location (usually referred to as the sample or matrix) to a physically separate location where further processing and analysis occur. Basically, extraction is the processes of separating a compound from a solid, liquid or a gas into a different solvent.
Usually, the extract goes to a fluid called the extracting solvent. However, extractions into the gas phase and solid sorbents are also common sometimes. In a laboratory, the most common extraction method is liquid-liquid extraction. We do it in a separatory funnel. In this process, we should first dissolve the component mixture in a suitable solvent. Then, the extracting solvent that is immiscible with the component mixture is added into the same funnel. Since the two liquids are immiscible, we can see two layers in the funnel.
Figure 01: Extraction Using a Separatory Funnel
When choosing solvents, we should choose a solvent that can dissolve all the components in the mixture and as the extracting solvent, we should choose a solvent that dissolves the analyte (the component that is to be extracted) very well. If we shake the funnel, the analyte will dissolve in the extracting solvent. Then, we can separate the component from the extracting solvent using an appropriate method, i.e. evaporation, recrystallization.
What is Isolation?
Isolation is a separation technique in which we can obtain a purified compound. Therefore we can call it “purification” as well. In this technique, we can remove all the foreign or contaminating substances in order to isolate the desired compound. To get a highly pure compound, we can do a series of extractions.
Figure 02: A Flow Chart for a Series of Extractions
In addition, there are several other methods that we can use for this purpose.
What is the Difference Between Extraction and Isolation?
Extraction is the process of moving one or more analytes from the sample or matrix to a physically separate location where further processing and analysis occur. Isolation is a separation technique in which we can obtain a purified compound. Therefore, the key difference between extraction and isolation is that extraction is a technique in which we can separate a compound from a mixture whereas isolation is a technique we use to purify the extracted compound.
Moreover, a further difference between extraction and isolation is that the purity of the end product in extraction is low while the purity of the end product is high in isolation techniques. Some techniques we can use for extraction include liquid-liquid extractions using separatory funnels, liquid-solid extractions, etc.while techniques for isolation include distillation, affinity purification, filtration, etc.
Summary – Extraction vs Isolation
In brief, extraction and isolation are two important techniques we can use to separate components in a mixture. The key difference between extraction and isolation is that extraction is a technique in which we can separate a compound from a mixture whereas isolation is a technique we use to purify the extracted compound.
Reference:
1. M.K.L. Bicking, Encyclopedia of Separation Science, 2000.
Image Courtesy:
1. “Liquid liquid extraction” By Sjantoni – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Liquid extraction111” By Rhannosh – Own work (CC BY-SA 3.0) via Commons Wikimedia