extraction methods (1).pptx

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1. EXTRACTS Defination : “Extracts are concentrated preparations of vegetable or animal drugs obtained by removal of the active constituents of the respective drugs with suitable menstrum , evaporation of all or nearly all of the solvent, and adjustment of the residual masses or powders to the prescribed standards.” Properties Extracts are potent preparations, usually between two and six times as potent on a weight basis as the crude drug. They contain primarily the active constituents of the crude drug, with a great portion of the inactive constituents (Although structural components of the crude drug having been removed).

2. Need for extraction Due to synthetic preparation of drugs ,demand is diminishing But still some plants and animal products are necessary like alkaloids, glycosides,proteins and require still extraction

3. Why separation of Active Principle is necessary Potency is more readily controlled Deterioration by enzyme is diminished Formulation is easy More stable and more palatable Tabletting of crude drug is not possible Storage and transport is easy

4. Extraction types There are two main types of extraction A- Solid-liquid extraction B- Liquid-Liquid extraction

5. Extraction processes (Solid –liquid extraction ) Infusion Pouring hot water from top and allow standing for stated time and temperature Decoction Boiling of drug with water for a time Digestion Maceration type require gentle heat Leaching process 1. Maceration Prolonged infusion,(2-14 days) 2. Percolation Menstrum is added from top

6. Liquid-Liquid extraction Extraction by using immisible solvents By using solvents heavier than water

7. Theory of extraction

8. Ideal Properties of solvent Be highly selective for the compound to be extracted. 2. Not react with the extracted compound or with other compounds in the plant material 3. Have a lowprice. 4. Be harmless to man and to the environment. 5. Be completely volatile. 6. Should not mix up with water. 7. Should have the big capacity in relation to extractive. 8. The density of solvent should be difference from water density. 9. Should have the minimum viscosity.

9. Maceration In this process solid ingredients are placed in a stoppered container with the whole of the solvent and allowed to stand for a period of at least 3 days (3 -7 days) with frequent agitation, until soluble matter is dissolved. The mixture is then strained (through sieves / nets), the marc pressed and the combined liquids clarified (cleaned by filtration) or by decantation, after standing.

10. TYPES OF MACERATION Maceration for organized drugs Maceration for unorganized drugs Multiple maceration (a) double maceration (b)triple maceration

11. . Organized drug Unorganized drug Cellular structure present such as leaves,stems , roots Direct part of plant Solid in nature Examples: tincture of squill , tincture of lemon , tincture of orange , tincture of gentian Cellular structure absent Products of plants & animals by extraction, distillation and expression Solid, liquid or semi-solid Ingredients are not enclosed in cell wall gums,resins . Oleogums Examples: tincture of benzoin , tolu and myrrh

12. Percolation It is continuous downward displacement of the solvent through the bed of crude drug material to get extract. Most frequently used to extract active ingredients in the preparation of tinctures and fluidextracts. It is the method of short successive maceration or process ofdisplacementA percolator (a narrow, cone-shaped vessel open at both ends) is generallyused.

13. Steps in Percolation 1.Comminution of drugs: The drug to be extracted is subjected to suitable degree of size reduction usually from coarse powder to fine powder To increase the surface area For uniform packing of percolator To slow down the movement of menstrum To ensure complete exhaustion

14. Continue 2.Imbibition or moistening of drug: The powdered drug is moistened with suitable amount of menstrum and allowed to stand for 4 hours in a well closed container Moistening of drug is necessary because If dried tissues are packed in percolator as such , they will swell up when come ion contact with menstrum and this will reduce porosity of material and choke the percolator It does not allow the fine particles to be washed out of percolator during percolation

15. Continue 3. Packing : After imbibition the moistened drug is packed evenly in a percolator A percolator is a conical vessel having a lid at the top and provided with a false bottom on which a filter paper or cotton wool is placed to support the column of drug . The base of percolator is fitted with a tap from which the percolate flows There are two types of percolators 1.Open percolator 2. Closed percolator

16. 4. Maceration After packing the column, sufficient menstrum is added to saturate the material and the top is covered with the lid When the liquid begins to drop from the top , tap at the bottom is closed If needed more menstrum is added to the top to maintain a layer over the crude drug The column should not be dry , otherwise cracks will appear in the packed column resulting in insufficient percolation The percolator is set aside for 24-hrs This time period is sufficient for the menstrum to penetrate deep into the tissues and dissolve out the maximum amount of active constituents

17. 5. percolation After 24 hrs of maceration of drugs , the lower tap of the percolator is opened and allow the liquid , collected therein to fall with a speed controlled , untill 3/4 th of the menstrum is obtained The more of menstrum is added so that marc does not become dry Menstrum is obtained again Now press the marc and liquid obtained is combined with previously obtained liquid This combined liquid is allowed to stand to settle suspended particles The liquid is drained or filtered

18. Industrial large scale extraction processes Large scale operation demands modifications of many extraction processes where the small scale directions are in appropriate Large scale extraction is carried out due to the following reasons Extensive demand of the drug Problem to handle the extraction process at laboratory level when more quantity of the drug is required Economic factors Improved efficiency of extraction For the preparation of concentrated preparations like liquid or solid extracts Reduced volume of solvent is used

19. 1. Circulatory extraction ( maceration) The efficiency of extraction in a maceration process can be improved by arranging for the solvent to be continuously circulated through the drug as indicated in the figure Solvent is pumped from the bottom of vessels to the inlet where it is distributed through the spray nozels over the surface of the drug Movement of the solvent reduces the boundry layers and the uniform distribution minimizes local concentrations in a shorter time Like the normal maceration process , however , extraction is incomplete since the mass transfer will cease when an equilibrium is setup This problem can be overcome by multiple stage process

20. Multiple stage extraction (maceration) The equipment needed for this process is a vessel for the drug together with a circulatory pump and spray distributors and a no of tanks to receive the extracted solution The extractors and tank are connected with piping and valves as shown in figure so that any of the tank may be connected to the extractor for the transfer of solution

21. Continue Advantages; The drug is extracted as many times as there are receivers – in this case, three. If more extraction stages are required, it is only necessary to have more receivers. The last treatment of the drug before it is discharged is with fresh solvent, giving maximum extraction. The solution is in contact with fresh drug before removal for evaporation, giving the highest possible concentration

22. Liquid-liquid extraction (solvent extraction) Definition: Solvent Extraction, also known as liquid-liquid extraction, is a method to separate compounds based on their relative solubilities in two different immiscible liquids, usually water and an organic solvent. Distribution coefficient "K“: When shaken, with two immiscible solvents, the compound will distribute itself between the two solvents. Normally one solvent is water and the other solvent is a water-immiscible organic solvent .

23. Continue Most organic compounds are more soluble in organic solvents, while some organic compounds are more soluble in water. This process is used for separating organic substances from aqueous solution. e.g. alkaloids. the aqueous solution of organic substances is shaken with an immiscible organic solvent such as ether or chloroform . The most of organic substances pass into ethereal or chloroform layer, distribution ratio being in favor of ether or chloroform.

24. Continue The amount of material extracted depends on: the amount of the material present, the partition coefficient , the volume of the solvents. The efficiency of the process can be increased by increasing the volume of the extracting solvent or by increasing the number of extraction

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