1 Experiment 1, 2 and 3 Comparative determination of glycosides in senna by using different methods of extraction (Soxhlet, maceration and ultrasonic bath) Aim: determine the yield among different extraction methods The extraction methods are: 1. Soxhlet extraction. 2. Liquid liquid extraction (Fractionation). 3. Percolation. 4. Decoction. 5. Sublimation extraction. 6. Steam distillation extraction. 7. Maceration. 8. Ultrasound-assisted solvent extraction. Soxhlet extraction The device is composed of a chamber that will contain the crude material in a thimble, a siphon is attached to it to drain the solvent back into the round bottom flask connected to the soxhlet device. A condenser should be attached to the top of the soxhlet to distil the solvent back into the soxhlet chamber. Figure-1 (Soxhlet extractor Instrument)
2 1: Stirrer bar 2: Still pot 3: Distillation path 4: Thimble 5: Solid 6: Siphon top 7: Siphon exit 8: Expansion adapter 9: Condenser 10: Cooling water in 11:Cooling water out A Soxhlet extractor is a laboratory apparatus invented in 1879 by Franz von Soxhlet. It was originally designed for the extraction of a lipid from a solid material. However, a Soxhlet extractor is not limited to the extraction of lipids. Typically, a Soxhlet extraction is only required where the desired compound has only: 1. A limited solubility in a solvent. 2. When impurities are insoluble in that solvent. (If the desired compound has a high solubility in a solvent then a simple filtration can be used to separate the compound from the insoluble substance). Normally a solid material containing some of the desired compound is placed inside a "thimble" made from thick filter paper, which is loaded into the main chamber of the Soxhlet extractor. The Soxhlet extractor is placed onto a flask containing the extraction solvent. The Soxhlet is then equipped with a condenser. The solvent is heated to reflux. The solvent vapor travels up a distillation arm, and floods into the chamber housing the thimble of solid. The condenser ensures that any solvent vapor cools and drips back down into the chamber housing the solid material. The chamber containing the solid material slowly fills with warm solvent. Some of the desired compound will then dissolve in the warm solvent. When the Soxhlet chamber is almost full, the chamber is automatically emptied by a siphon side arm, with the solvent running back down to the distillation flask. This cycle may be allowed to repeat many times, over hours or days. During each cycle, a portion of the non-volatile compound dissolves in the solvent. After many cycles the desired compound is concentrated in the distillation flask. The advantages of this system 1. Is that, instead of many portions of warm solvent being passed through the sample, just one batch of solvent is recycled. 2. Good for lipid extraction. 3. The repetitive extraction cycles will enable larger amount of the substances to be extracted. 4. Good for heat liable substances (there is no direct contact between the heat and the crude drug).
3 5. Economic method. 6. Minimum loss of the solvent. After extraction the solvent is removed, typically by means of a rotary evaporator, yielding the extracted compound. The non-soluble portion of the extracted solid remains in the thimble, and is usually discarded. Disadvantages 1. Poor extraction of polar lipids. 2. Long time involved. 3. Large volumes of solvents are used. 4. Hazards of boiling solvents. Experimental Procedure Plants used 1-Senna leaves, which consist of the dried leaflet of Cassia acutifolia, Fam: Leguminosae. 2-Rhubarb or Rheum officinale Fam: Polygonacaea. Both contains anthraquinone glycosides and are used as cathartic. C6H115 - H C6H115 - H H H CH CH H CH C6H115 - H Rhein-8-glucoside Sennoside A Figure-4 (The chemical structure of Rhein and Sennodide A)
4 Procedure Powder the crude drug to coarse particles using mortar and pestle, weigh the powder and place it inside the thimble. Place the thimble inside the soxhlet extractor (thimble chamber). Use (300ml) 80% ethanol as solvent in the round flask. Connect the apparatus (round flask containing the solvent, the thimble chamber and the condenser) place them on the hot plate. Start reflux (heating) and adjust the temperature to 80 o C, adjust the time. Start to extract with the extractor instrument for at least 1:30 hr to allow several cycles of extraction, (record the time and the number of extractions where the solvent is recycled). Discharge the thimble from the thimble chamber and weight the crude material after extraction. Recover the solvent from the extract using a rotary evaporator. Collect the thick extract after evaporating the solvent from the rotary evaporator and weigh. Ultrasonic extraction Sonication is the act of applying sound energy to agitate particles in a sample, for various purposes.
5 Employed for a great number of different plant materials. Initial extraction of a small amount of material. Procedure: Weigh the powder and place it inside the jar with the same solvent. The mixture with the same composition was placed into the ultrasound assisted extractor and sonicated at a frequency of 30 (khz) for 30 minutes, without stirring. Filter the sample, evaporate the solvent using a rotator evaporator and collect the thick extract. Weigh and compare the yields of all extraction methods. Maceration: Perform the extraction with macerate the crude plant part with the same solvent and compare the yield. (Weight the powder and place it inside the jar). Leave the materials in the jar for 1 week. Followed by filtration. Evaporate the solvent and collect the thick extract. Weigh and compare the yields of all extraction methods.