Separation Techniques, Fibre and Surgical Dressing (PCG 3301) PDF

SEPARATION TECHNIQUES, FIBRE AND SURGICAL DRESSING
(PCG 3301)


FOR 300 LEVEL (PHARM D.) BY ABBA ANAS DEPARTMENT OF PHARMACOGNOSY AND HERBAL MEDICINE...

SEPARATION TECHNIQUES, FIBRE AND SURGICAL DRESSING
(PCG 3301)


FOR 300 LEVEL (PHARM D.) BY ABBA ANAS DEPARTMENT OF PHARMACOGNOSY AND HERBAL MEDICINE FACULTY OF PHARMACEUTICAL SCIENCES COLLEGE OF NATURAL AND PHARMACEUTICAL SCIENCES BAYERO UNIVERSITY KANO ABBA Anas  INTRODUCTION Plant and animal materials are very complex in their composition, and our knowledge of the chemistry of many of their constituents is very limited so that a proximate chemical analysis is often all that is possible. A natural product is a chemical compound or substance produced by a living organism. They may be extracted from tissues of terrestrial plants, marine organisms or micro-organisms. ABBA Anas  EXTRACTION PROCESSES Are separation techniques that are used to separate mixtures into its constituent elements/compounds. Recall that a mixture contains elements/compounds which are not chemically combined together. By separating the constituents of the mixtures, we are able to f ind out the properties of the known/unknown substances from mixtures and possibly use them for the production of useful substances such as medicines. Depending on the physical and chemical properties of the substances in the mixture, we can choose the most appropriate separation technique to isolate them from the mixture. ABBA Anas 
EXTRACTION PROCESSES CONT’D

Definitions  Extraction: may be def ined as the treatment of the plant or animal tissues with solvent, whereby the medicinally active constituents are dissolved and most of the inert matter remains undissolved the solvent used for extraction is known as Menstruum and the inert insoluble material that remains after extraction is called Marc  Extraction: It may also be def in ed as the treatment of plant or animal tissues with appropriate solvent, which would dissolve the medicinally active constituents  Extraction: could be the method of removal of a soluble fraction in the form of a solution from insoluble matrix with the help of a suitable solvent ABBA Anas  EXTRACTION PROCESSES CONT’D Example: Boiling tea  Extraction: involves the separation of medicinally active portion of plant or animal tissues from the inactive components through the use of selective solvents and standard extraction process  Marc: The inert fibrous and insoluble materials remaining after extraction.  Menstruum: Solvent used for extraction (Water, alcohol ether, acetone, ethyl acetate e.t.c). It could be Polar or Non polar Polar : water (Di-electric constant: 80), Methanol :33, acetone : 21, Ethanol : 25, Dimethyl sulfoxide : 49 Non –polar: chloroform (4.81), Hexane (1.88), Benzene (2.3), toluene (2.38). Generally solvents with dielectric constant of less than 15 are considered to be non polar. ABBA Anas  EXTRACTION PROCESSES CONT’D  Extractives: concentrated preparation of vegetable or animal drugs obtained by removal of the active constituents of the respective drug with suitable menstruum, evaporation of all or nearly all solvent.  Tinctures: are alcoholic or hydroalcoholic solutions prepared from vegetable material or from chemical substances e.g belladonna tincture Expression: is a method of fragrance extraction where raw materials are pressed, squeezed or compressed and the oils are collected. Galenicals: these are extracts initially obtained by leaching the vegetables or animal tissues with suitable solvents which were concentrated and converted into a dry extracts, ABBA Anas  EXTRACTION PROCESSES CONT’D A viscous extracts, liquid extracts. These crude extracts when standardized are known as galenicals. Some of the products that are obtained after extraction process may be summarize as  Extraction of fixed oils from seeds  Preparation of alkaloid as quinine from Cinchona bark  Extraction of Morphine from Opium  Reserpine from Rauwolfia serpentina ABBA Anas 
Classification of Extraction
 Solid-Liquid extraction (leaching) The separation of soluble constituent from a solid by extraction with a solvent. It consist of two stages:- 1. Contact of solute with the liquid phase 2. Separation of the liquid phase from solid phase ABBA Anas 
Liquid –Liquid Extraction

 Known as solvent extraction or partitioning, it is a method to separate compounds based on their relative solubilities in two different immiscible liquid usually water and organic solvent.  Is a basic technique performed using separatory funnel, a solvent (known as the “extractive solvent”) is brought in contact with another solvent (termed as the “solute bearing solvent”) in order to bring about the transfer of one or more solute into the f irst solvent.  Separation of a substance from a mixture by preferentially dissolving the substance in a suitable solvent. ABBA Anas Liquid –Liquid Extraction Cont’d ABBA Anas 
Solvents used for extraction process

The ideal solvent(s) for a certain pharmacological activity(ies) should: - Be highly selective for the compound to be extracted - Have a high capacity for extraction - Not react with the extracted compound or with other compound in the plant material - Have a low price - Be harmless to man and to the environment - The generally used solvent includes: water, ether, alcohol, chloroform etc. ABBA Anas 
Advantages of water as Menstruum

o Readily available o Cheapness o Good solvent action for many plants constituents o Used with other solvents ABBA Anas Disadvantages of water as a solvent

o Most active plant constituents are complex organic chemical which are less soluble in water o Plant constituents such as sugars, gums, starches, colouring agents, tannins, are easily extracted by water, however are not desirable component sometimes and may interfere with clarity of the preparation. o Aqueous preparation serve as excellent growth for molds, yeasts and bacteria. Preservatives should be added such as alcohol o Maximum amount of heat is needed to concentrate the extraction than non-aqueous solvent. ABBA Anas 
Alcohol as a Menstruum

 Solvent of alkaloids, alkaloid salts, glycosides, volatile oils and resins  Also dissolves many forms of coloring matter, tannins, and many organic acids and salts  Alcohol does not dissolve albuminous matter, gums, waxes fats, fixed oils and sugars. ABBA Anas 
Advantages
o No microbial contamination in alcohol solution containing 20 % or more concentration o A small amount of heat is needed to concentrate the alcoholic preparation o Non- toxic o Dissolves selected active constituents of drugs ABBA Anas 
Disadvantages
o Costly o Flammable ABBA Anas 
EXTRACTION PROCESSES

Infusion:- is the process of extracting chemical compounds or flavors from plant material in a solvent such as water, oil or alcohol by allowing the material to remain suspended in the solvent overtime (a process often called steeping).  An infusion is also the name of the resultant liquid.  It is used for drugs which are soft in nature so that water may penetrate easily into the tissues and the active constituents are water soluble  it involves pouring water over drugs and allowing it to keep in contact with water for the stated period, usually for 3-7 minutes, with occasional stirring and f in ally f il tering off the liquid and dispense as drug  Boiling water commonly used as solvent. ABBA Anas 
DECOCTION

 This is another process of extraction in which the water soluble and heat stable constituents of hard and woody crude drugs are extracted out.  Water is used as a solvent and the crude drug which is to be extracted is cut into small pieces and boiled with water for the stated time, usually 10 to 15 minutes e.g Cinchona bark or wood ABBA Anas 
CONCOCTION

Is another process of extraction in which mixtures of two or more drugs that have been heated for a specified period of time ABBA Anas 
DIGESTION

Digestion is the process in which heat as well as pressure is used for extraction  The equipment is like a pressure cooker or autoclave and is called digester.  Extraction of non-thermolabile material is more eff ic ient in it , because of high penetration power of solvent and solubilisation rate of soluble matters of the crude drug due to high pressure and temperature. ABBA Anas 
MACERATION

Various types of Maceration process are: Simple Maceration: A process for tinctures made from organized drug e.g roots, stems, leaves etc Maceration with adjustment: A process for tincture made from unorganised drugs such as Oleo resins and gum resins Double and Triple maceration Process: for concentrated preparation. ABBA Anas 
Simple Maceration

 Drug is placed in wide mouthed container which can be well stopped to prevent the evapo ratio n o f Menstrum whic h is mo stly concentrated alcohol.  The drug is placed with the whole of menstruum in a closed vessel for 7-days.  During this period shaking is done occasionally  After 7 days liquid is strained and marc is pressed in f ilter press, hydraulic press or hand press.  The liquid is f il tered and the f in al volume is not adjusted eg tincture of orange, tincture of lemon ABBA Anas 
Maceration with Adjustment

The unorganised drug is placed with 4/5th of menstrum in a closed vessel for a period of 2-7 days  Shaking is done occasionally  After the stated period, the liquid is f iltered and f inal volume is made up by passing the remaining 1/5th of the menstruum through the filter.  The marc is not pressed eg tincture of tolu, compound tincture of benzoin. ABBA Anas  Multiple Maceration Multiple Maceration: it is used to established that, maximum extraction is obtained in multiple maceration when total quantity of menstrum to be used is divided in such a way that some quantity of menstrum is present during each maceration. Some time single extraction process is not suff icient in the above, whole process is repeated to make to extraction process more effective Note that: no change in the process just repeat the procedure for specified times (2-4) times all other things is the same. ABBA Anas 
Percolation

Percolation:- is a continuous flow of the solvent through the bed of the drug material to get the extract. 1. Simple percolation or percolation process for tinctures 2. Percolation processes for concentrated preparation such as i. Reserve percolation process ii. Modified percolation process iii. Continuous hot percolation or soxhelation Percolation - Apparatus  Conical Percolator  Cylindrical Percolator  Stem jacketed percolator ABBA Anas ABBA Anas 
Simple Percolation

There are three stages in the official method for preparation of tincture by percolation process 1. Imbibition Powdered drug is moistened with a sufficient quantity of menstrum and allowed to stand for 4 hour in a closed vessel  It is done in order to allow swelling of the tissues before packing into percolator because: If dry powder is packed into percolator may cause blockage of the percolator It allows entrapped air to escape, dry powder drug would have air entrapped within them, this may resist the flow of menstrum and will disturb the packing of the powdered drug  Prior to packing of the imbibed drug into percolator uniformity of the particle size is ensured by passing the Moistened mass through a sieve of coarse aperture ABBA Anas  Simple Percolation Cont’d  Glass wool moistened with solvent is kept at the bottom to avoid blockage of outlet or tap  The imbibed drug is packed into the percolator up to 2/3rd or 3/4th of the volume of percolator  Filter paper is placed above the sand layer in order to prevent disturbance of top layer when the menstruum is added into the percolator  Sufficient quantity of menstrum needs to be added to saturate the material  when the liquid start coming out of the percolator outlet is closed and menstrum is added forming a layer of solvent above the imbibed mass. ABBA Anas  2. Maceration The moistened drug is left in contact with menstruum for 24 hr, during this period menstruum dissolved the active constituents of the drug and become almost saturated with it 3. Percolation  I t c o ns is t o f the do wnward dis plac em ent o f the saturated solution formed by maceration and extracting the remaining active constituents present in the drug by the slow passage of the menstruum through the column of the drug.  After collecting 3/4 th of the required volume of the finished product or when the drug is completely exhausted, the marc is pressed  The liquid is mixed and sufficient ABBA Anas quantity of menstruum Percolation process for Concentrated Preparation  Used to prepare liquid extracts and Solid extracts Types of the processes are:- i. Reserve Percolation process ii. Modified Percolation process Reserve Percolation process  In this process, a part of the percolate usually 3/4th of the volume of the f in ished preparation is reserved (first percolate) containing high solute concentration.  The process is continued till the drug is completely exhausted  The percolate thus receives contains traces of active constituents of the drug  Evaporation or distillation is done to recover the costly menstrum ABBA Anas Modified Percolation Process  In percolation process, the drug/percolate (d/p) ratio about 1: 4, the (d/p) is reduced to 1:3 by modifying the percolation process and hence there is a lot of saving in heat, time and menstruum.  Percolation is the displacement process  The strong solution of active constituents of drug formed during maceration is displaced by the fresh menstruum when percolation process is started.  Menstruum remaining in contact with the drug dissolves more matter then the flowing menstruum ABBA Anas  Continuous hot Percolation Process or Soxhlet Extraction or Soxhleation  When active constituents of the drug are not freely soluble in the solvent or diff icult to be displaced from the cells of the drug, then it becomes necessary to extract the crude drug by action of hot menstrum for a considerable length of time.  The fixed oils from seeds and alkaloids from the drug are extracted by continuous hot percolation process using benzene, chloroform, petroleum ether etc. Soxhlet Apparatus 1. Flask containing the boiling menstrum 2. Soxhlet Extractor: in which the drug to be extracted is Packed. It has a side tube which carries ABBA Anas the vapors of the solvent Over the extract from soxhlet extractor to the flask. A condenser in which the vapors of the solvent are condensed again into solvent. Fig. 2: Soxhlet ABBA Anas Apparatus  Procedure  The drug is packed in a porous bag or “thimble” made of strong f ilter paper and it is placed in the body of soxhlet extractor. The solvent is placed in the flask. The apparatus is then fitted as shown in Fig. 2  When solvent is boiled on heating the flask, it gets conver ted into vapors. These vapors enter into the condenser through the side tube and get condensed into hot liquid which falls on column of the drug.  when the extractor gets f illed with solvent, the level of siphon tube also raises up to its top.  The solvent containing active constituents in the siphon tube siphon over and run into the flask, thus emptying the body of extractor. ABBA Anas  This alteration of f il ling and emptying the body of extractor goes on continuously until the drug is exhausted (1-2 hr)  The soluble active constituents of the drug remain in the flask where solvent is repeatedly volatilized Factors Affecting the Choice of Extraction Process 1. Character of drug 2. Therapeutic value of the drug When drug has high therapeutic value, maximum extraction is required so percolation process is used eg Belladonna 3. Cost of drug Costly drugs are extracted by percolation process where as cheap drug are extracted by maceration process. ABBA Anas 4. Stability of drug Maceration or Percolation should be done Note: No hot extraction process should be carries out. 5. Solvent (Menstrum)  Maceration process is recommended if water is used as solvent  Percolation process is recommended for non-aqueous solvent. ABBA Anas  GENERAL SEPARATION TECHNICS Substances in a mixture are physically combined, so processes based on differences in physical properties are used to separate component. This can be achieved using the following processes; decantation, filtration, sublimation, distillation, crystallization techniques. ABBA Anas Decantation It is simply to pour off of upper liquid layer Used to separate a liquid from an insoluble solid. The solid stays in the bottom. ABBA Anas filtration Used to separate heterogeneous mixtures composed of solids and liquids Uses a porous barrier to separate the solid from the liquid Liquid passes through leaving the solid in the filter paper ABBA Anas  SUBLIMATION

(Separating a solid that sublimes on heating) Sublimation is the process whereby the substances changes from the solid that sublimes upon heating from another substance with a high melting point. The mixture is placed in an evaporating dish. An inverted funnel is placed over the mixture. On gentle heating, the salt sublimes and deposited on cold filter funnel. This method has limited uses because very few solids will sublime on heating. For e.g. ammonium salts, iodine, dry ice (CO2) ABBA Anas Distillation Used to separate homogeneous mixtures Based on differences in boiling points of substances involved Types; Simple distillation Fractional distillation. ABBA Anas Simple This is a technique used to separate a mixture of a soluble substance and a solvent. E.g salt and water ABBA Anas Fractional Distillation This is the technique used to separate a mixture of two or more miscible liquids with different boiling points. A tall fractionating column is used. It allows the separation of different liquids more eff ic iently. It contains many glass beads which provides a large surface area for the vapour to condense on. The substance with a lower boiling point is distilled first. Uses : Separation of liquid air Separation of crude oil ( or petroleum) Separation of ethanol from glucose solution E.g water and ethanol. The boiling point for water is 100 while for ethanol it is 78. ABBA Anas Fractional Distillation Cont’d ABBA Anas Crystallization Separation technique that results in the formation of pure solid particles from a solution containing the dissolved substance As one substance evaporates, the dissolved substance comes out of solution and collects as crystals Produces highly pure solids Rocky candy is an example of this ABBA Anas Crystallization steps the liquid from a solution has evaporated to a point beyond the solubility limit. ABBA Anas CHROMATOGRAPHY Separates components of a mixture based on ability of each component to be drawn across the surface of another material Mixture is usually liquid and is usually drawn ac ro ss chromatography paper Separation occurs because various components travel at different rates Components with strongest attraction for paper travel the slowest ABBA Anas