Extraction is the first crucial step in phytochemical analysis, aiming to isolate bioactive compounds from plant material.
Modern extraction methods focus on improving efficiency, reducing solvent usage, and preserving compound integrity.
Conventional Extraction Techniques
Conventional methods have been used for a long time and rely primarily on heat and solvent use to extract bioactive compounds.
These methods are widely accepted due to their simplicity, but they often require longer extraction times and large amounts of solvents.
1) Maceration
Maceration is a simple extraction technique where the plant material is soaked in a solvent for a specified period to dissolve bioactive compounds.
Construction & Apparatus
A container (glass or stainless-steel vessel) with a wide mouth.
Solvent (such as ethanol, methanol, or water).
Filtration apparatus (such as filter paper or a mesh strainer).
Procedure/Working
The plant material is finely powdered or cut into small pieces to increase the surface area.
The material is soaked in an appropriate solvent (like ethanol or water).
The mixture is kept at room temperature for 1–3 days, stirred occasionally.
The liquid extract is filtered to separate the solvent from the plant residue.
The solvent is evaporated to obtain the concentrated extract.
Advantages
Simple, cost-effective, and does not require special equipment.
Disadvantages
Slow, requires large amounts of solvent, and has low efficiency.
2) Percolation
Percolation is a continuous process where fresh solvent passes through a column packed with plant material to ensure efficient extraction.
Construction & Apparatus:
Percolator (a cylindrical vessel with a perforated bottom).
Solvent (ethanol, methanol, or water).
Collection flask to gather the extract.
Procedure/Working:
The finely powdered plant material is moistened with the solvent and placed in a percolator.
The solvent is added gradually to allow thorough saturation.
The percolator is kept for 24 hours, allowing the solvent to dissolve the bioactive compounds.
The extract is collected dropwise from the percolator.
The extract is concentrated by evaporation.
Advantages
Continuous extraction, efficient use of solvent, and faster than maceration.
Disadvantages
Requires more apparatus, and solvent selection is crucial.
3) Soxhlet Extraction
Soxhlet extraction is a more efficient conventional method that uses continuous recycling of the solvent to extract bioactive compounds.
Construction & Apparatus:
Soxhlet extractor (a glass apparatus with a siphon and thimble holder).
Round-bottom flask (for holding the solvent).
Reflux condenser (to condense and recycle solvent).
Solvent (ethanol, methanol, hexane, etc.).
Procedure/Working:
The dried plant material is placed inside a thimble in the Soxhlet extractor.
The solvent is heated in the round-bottom flask to produce vapors.
The vapors rise and condense in the reflux condenser.
The condensed solvent continuously percolates through the plant material, extracting bioactive compounds.
Once the cycle is complete, the solvent is evaporated to concentrate the extract.
Advantages
Efficient, extracts more bioactive compounds, and requires less solvent compared to maceration.
Disadvantages
High temperature may degrade heat-sensitive compounds, and the process requires a long extraction time.
Modern Extraction Techniques (Modern Methods of Extraction)
Modern methods of extraction are developed to overcome the limitations of conventional methods.
These techniques enhance efficiency, reduce solvent usage, and ensure better preservation of bioactive compounds.
Mind-map of Modern Extraction Techniques
1) Microwave-Assisted Extraction (MAE)
This method uses microwave energy to accelerate the extraction process by increasing the temperature and pressure inside the extraction vessel.
Procedure/Working:
The plant material is placed in a microwave-transparent vessel.
The solvent (ethanol, water, or acetone) is added to cover the material.
The system is exposed to microwave radiation, which heats the solvent and breaks the plant cell walls.
The extract is collected and filtered to separate the solid and liquid phases.
The solvent is evaporated to obtain the final extract.
Advantages
Rapid extraction, energy-efficient, and less solvent consumption.
Disadvantages
High heat may degrade sensitive compounds, and specialized equipment is required.
2) Pressurized Liquid Extraction (PLE) (Accelerated Solvent Extraction)
PLE uses high pressure and temperature to enhance the extraction efficiency while minimizing solvent usage.
Procedure/Working
The plant material is loaded into a high-pressure extraction chamber.
A suitable solvent (ethanol, methanol, or water) is introduced.
The chamber is heated to 50–200°C and pressurized (10–15 MPa).
The increased temperature and pressure improve the solubility and diffusion of bioactive compounds.
The extract is collected and filtered to obtain the final concentrated solution.
Advantages
High efficiency, less solvent required, and better compound recovery.
Disadvantages
Expensive equipment and requires precise control of pressure and temperature.