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Extraction

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Extraction Process and Techniques

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Extraction

  1. 1. EXTRACTION Dr: Fatehalrahman Magbool, PhD Assist. Professor of Pharmaceutics
  2. 2. Definition • Extraction is the first step to separate the desired natural products from the raw materials. • The process of isolation of active ingredients or active substances or active medicaments from raw materials of either plants or animals or directly from the natural sources with the help of solvent is called extraction. • In Extraction the mixture of substances is dissociated, by dissolving each component with one or other solvents which yields two phases – Raffinate Phase (rich in Feed Solvent) and Extract Phase (rich in Solute)
  3. 3. General Terms • Marc: • The unwanted or insoluble substances left behind after the process of extraction is called marc. These are not used for further purpose in the process of extraction. • Menstrum • The solvent used in the process of extraction is called solvent. The most commonly used menstrum is water.
  4. 4. Objectives of Extraction • To obtain the therapeutic portion of dosage form from raw materials and to eliminate the unwanted or inert material by treatment with solvent. • They play a decisive role in the determination of qualitative and quantitative composition of extracts. • The extracts obtained are also utilized for the isolation and characterization of therapeutically active chemical constituents.
  5. 5. Extraction Types • Liquid-Liquid Extraction • Solid-Liquid Extraction
  6. 6. Liquid-Liquid Extraction • Solution of substance is brought into contact with another solvent for the substance that is immiscible with first solvent • A concentration gradient is set up between the phases and mass transfer will occur until an equilibrium is established • As the process is controlled by mass transfer the liquid must be thoroughly mixed to give a large enough surface area for contact sufficient time must be allowed in the dispersed for equilibrium to be set up • The liquid are separated
  7. 7. Solid-Liquid Extraction • Extraction of soluble constituents from a solid or semi-solid by means of suitable solvent • Examples: • Extraction of fixed oils from seeds • Preparation of alkaloids • Isolation of hormones
  8. 8. Extraction Methods • include solvent extraction, distillation method, pressing and sublimation according to the extraction principle. • Solvent extraction is the most widely used method. • The extraction of drug progresses through the following stages: (1) the solvent penetrates into the solid matrix; (2) the solute dissolves in the solvents; (3) the solute is diffused out of the solid matrix; (4) the extracted solutes are collected.
  9. 9. Factors Affecting Extraction • Any factor enhancing the diffusivity and solubility in the above steps will facilitate the extraction. • The properties of the extraction solvent. • The physicochemical properties of drug. • The particle size of the raw materials. • The solvent-to-solid ration. • The extraction temperature. • The extraction duration.
  10. 10. • The physical properties which effect the drug extraction are: 1. Gravitation 2. Diffusion 3. Osmosis 4. Adhesion 5. Capillarity 6. Convection 7. Solubility 8. Surface tension • Wetting property of solvent can be improved by displacing the air entrapped in the capillaries and also by using surface active agent. Surfactant can increase the solubility by means of solubilization.
  11. 11. • The selection of the solvent is crucial for solvent extraction. • Selectivity, solubility, cost and safety should be considered in selection of solvents. • It should also be have a low viscosity, not inflammable and chemically and physically inert. • Based on the law of similarity and intermiscibility (like dissolves like), solvents with a polarity value near to the polarity of the solute are likely to perform better and vice versa.
  12. 12. • The main solvents used in the process of extraction are: • 1. Water • 2. Alcohol • 3. Ether • 4. Chloroform • 5. Light petroleum
  13. 13. • Advantages Water as Solvent i. It is very cheap ii. It has wide solvent action iii. It is non-toxic iv. It is inflammable • Disadvantages Water as Solvent i. Microbial contamination will occur ii. It is non-selective iii. It promotes hydrolysis iv. It also promotes enzymatic degradation
  14. 14. • Advantages of Alcohol 1. Has wide solvent action 2. No chance for the bacterial growth 3. It is non-toxic 4. Neutral in nature and also show compatibility with the pharmaceutical product 5. Absorption of constituents is more than water 6. It is selective 7. No additional preservatives were required 8. Requires less heat when compared to water • Disadvantages of Alcohol 1. It is costly
  15. 15. • Advantages of Ether a. It is inflammable • Disadvantages of Ether a. It is costly b. It has a physiological effect c. It is unsuitable for internal administration.
  16. 16. • Advantages of Chloroform a. it is inflammable • Disadvantages of Chloroform a. It is costly b. It has a physiological effect c. It is unsuitable for internal administration.
  17. 17. • Advantages of Light Petroleum a. It is inflammable • Disadvantages of Light Petroleum a. It is costly b. It has a physiological effect c. It is unsuitable for internal administration
  18. 18. The Conventional Extraction Techniques • The Conventional Extraction Techniques Extraction process infusion decoction maceration percolation digestion Fresh infusion concentrated Simple maceration Maceration With adjustment Multiple maceration Simple percolation Percolation for concentrated preparation Continuous percolation
  19. 19. The Conventional Extraction Methods 1. Infusion pouring of water over the drugs and then allowing it to keep in contact with water for the stated period , usually 15 minutes, with occasional stirring and finally filtering off the liquid. • The marc is not pressed . • The boiling water is commonly used as a solvent
  20. 20. • There are two types of infusion • a. Fresh infusion • Afresh infusion is an aqueous solution of active constituents of vegetable drug prepared by the process of infusion. • Coarse powder of drug is used in the preparation of infusion. • Water used as menstrum ( because it has more penetration power and dissolves the active constituents of the drug ). • Pharmacopoeia states that fresh infusion should be used with in 12 hours after its preparation because it gets spoiled due to fungal or bacterial growth.
  21. 21. b. concentrated infusion • Concentrated infusions are prepared by double or triple maceration process. • Concentrated infusions are eight times stronger than the fresh infusion. • Alcohol in the concentration of 20 – 25% is used as menstrum. Hence these preparations can be stored for a longer period due to preservative action of alcohol.
  22. 22. 2. Decoction • In this process , the drug is boiled with water for stated period usually10 minutes. After boiling, the liquid is strained and water is passed through the content of the strainer to make the required volume. • This process is mainly used for vegetable drugs of hard and woody nature having thermos table water soluble constituents. • The extract from decoction contains a large amount of water-soluble impurities. Decoction cannot be used for the extraction of thermolabile or volatile components.
  23. 23. 3. Maceration • This is a very simple extraction method with the disadvantage of long extraction time and low extraction efficiency. • It could be used for the extraction of thermolabile components. • The various types of maceration process are: • a. simple maceration • In this process the drug is placed with the whole of the menstrum in a closed vessel for seven days. During this period shaking is done occasionally. After seven days , the liquid is strained and marc is pressed.
  24. 24. • The expressed liquid is mixed with strained liquid . It is then filtered to make a clear liquid . The final volume is not adjusted . • Example: The tinctures made by simple maceration are: • (1) Tincture of orange . • (2) Tincture of lemon. • b. maceration with adjustment • A process for tinctures made from un organized drugs such as oleo resins and gum resins . This process is known as (maceration with adjustments), Example of the tinctures made by maceration with adjustment are: compound tinctures of benzoin.
  25. 25. c. multiple maceration process process for concentrated preparations which include both (Double Maceration ) and ( Triple Maceration ) • Multiple maceration process is carried out in the same way as simple maceration process , but the menstrum used is divided into two parts in double maceration process and into three parts triple maceration process. • Example for concentrated infusion prepared by double maceration process: concentrated infusion of orange. • Example for concentrated infusion are prepared by triple maceration: Liquid Extract of Senna.
  26. 26. 4. Percolation • Percolation is more efficient than maceration because it is a continuous process in which the saturated solvent is constantly being replaced by fresh solvent. • The various percolation process used for the extraction of drug are:- • 4.1. simple percolation or percolation process for tinctures: • Apparatus (1) conical percolator (2) cylindrical percolator (3) steam jacketed percolator
  27. 27. • Method: • there are three stages: • i) Imbibition • The powdered drug is moistened with sufficient quantity of menstrum and allowed to stand for 4 hours in a closed vessel. • ii) Maceration • the moistened drug is left in contact with menstrum for 24 hours . During this period, the menstrum dissolves the active constituents of the drug and becomes almost saturated with it. • iii) percolation • It consists of the down ward displacement of the saturated solution formed in maceration and extraction of the remaining active constituents present in the drug by the slow passage of the menstrum through the column of the drug . Example:- strong tincture of ginger.
  28. 28. • 4.2. percolation process for concentrated preparations • percolation process for concentrated preparations are used for preparing concentrated preparations are: • A) reserve percolation process • B) modified percolation process
  29. 29. • A) reserve percolation process • In this process, generally ¾ th the volume of the finished preparation, is reserved. Then the percolation process is continued till the drug is completely exhausted. The percolate is subjected to evaporation or distillation to convert it into a soft extract. This soft extract is dissolved in the reserve portion of percolate and then sufficient menstrum is added to produce the required volume.
  30. 30. • 4.3. Modified percolation process • The ratio between drug : percolate is reduced by modifying the percolation process and hence there is a lot of saving in heat, time and menstrum.
  31. 31. Soxhlet extraction (Continuous hot percolation process or soxhelation) • The Soxhlet extraction method integrates the advantages of the reflux extraction and percolation, which utilizes the principle of reflux and siphoning to continuously extract the herb with fresh solvent. The Soxhlet extraction is an automatic continuous extraction method with high extraction efficiency that requires less time and solvent consumption than maceration or percolation. • The high temperature and long extraction time in the Soxhlet extraction will increase the possibilities of thermal degradation.
  32. 32. 5. Digestion • The drug is extracted by heating at particular pressure. This will increase the penetration power of the menstrum, so that there is complete extraction of the drug.
  33. 33. 6. Reflux extraction • Reflux extraction is more efficient than percolation or maceration and requires less extraction time and solvent. • It cannot be used for the extraction of thermolabile natural products.
  34. 34. Modern or Greener Extraction Methods 1. Pressurized liquid extraction (PLE) • (PLE) has also been described as accelerated solvent extraction, enhanced solvent extraction, pressurized fluid extraction, accelerated fluid extraction, and high pressure solvent extraction by different research groups. • PLE applies high pressure in extraction. High pressure keeps solvents in a liquid state above their boiling point resulting in a high solubility and high diffusion rate of lipid solutes in the solvent, and a high penetration of the solvent in the matrix. PLE dramatically decreased the consumption of extraction time and solvent and had better repeatability compared to other methods.
  35. 35. 2. Supercritical fluid extraction (SFE) • (SFE) uses supercritical fluid (SF) as the extraction solvent. SF has similar solubility to liquid and similar diffusivity to gas, and can dissolve a wide variety of natural products. Their solvating properties dramatically changed near their critical points due to small pressure and temperature changes. • Supercritical carbon dioxide (S-CO2) was widely used in SFE because of its attractive merits such as low critical temperature (31 °C), selectivity, inertness, low cost, non- toxicity, and capability to extract thermally labile compounds.
  36. 36. • The low polarity of S-CO2 makes it ideal for the extraction of non-polar natural products such as lipid and volatile oil. • A modifier may be added to S-CO2 to enhance its solvating properties significantly.
  37. 37. 3. Ultrasound assisted extraction (UAE) • Also called ultrasonic extraction or sonication, uses ultrasonic wave energy in the extraction. Ultrasound in the solvent producing cavitation accelerates the dissolution and diffusion of the solute as well as the heat transfer, which improves the extraction efficiency. • The other advantage of UAE includes low solvent and energy consumption, and the reduction of extraction temperature and time. • UAE is applicable for the extraction of thermolabile and unstable compounds. UAE is commonly employed in the extraction of many types of natural products
  38. 38. 4. Microwave assisted extraction (MAE) • Microwaves generate heat by interacting with polar compounds such as water and some organic components in the plant matrix following the ionic conduction and dipole rotation mechanisms. The transfers of heat and mass are in the same direction in MAE, which generates a synergistic effect to accelerate extraction and improve extraction yield. • The application of MAE provides many advantages, such as increasing the extract yield, decreasing the thermal degradation and selective heating of vegetal material.
  39. 39. • MAE is also regraded as a green technology because it reduces the usage of organic solvent. • There are two types of MAE methods: solvent-free extraction (usually for volatile compounds), and solvent extraction (usually for non-volatile compounds)
  40. 40. 5. Pulsed electric field (PEF) extraction • Pulsed electric field extraction significantly increases the extraction yield and decreased the extraction time because it can increase mass transfer during extraction by destroying membrane structures. • The effectiveness of PEF treatment depends on several parameters including field strength, specific energy input, pulse number and treatment temperature. • PEF extraction is a non-thermal method and minimizes the degradation of the thermolabile compounds.
  41. 41. 6. Enzyme assisted extraction (EAE) • The structure of the cell membrane and cell wall, micelles formed by macromolecules such polysaccharides and protein, and the coagulation and denaturation of proteins at high temperatures during extraction are the main barriers to the extraction of natural products. • The extraction efficiency will be enhanced by EAE due to the hydrolytic action of the enzymes on the components of the cell wall and membrane and the macromolecules inside the cell which facilitate the release of the natural product. Cellulose, α-amylase and pectinase are generally employed in EAE.
  42. 42. 7. Hydro distillation (HD) and steam distillation (SD) Are commonly used methods for the extraction of volatile oil. • Some natural compounds encounter decomposition in HD and SD.
  43. 43. THANKS

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