Soxhlet extractor and thin layer PDF

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Soxhlet extractor A Soxhlet extractor has three main sections: a percolator (boiler and reflux) which circulates the solvent, a thimble (usually made of thick filter paper) which retains the solid to be extracted, and a siphon mechanism, which periodically empties the thimble.

Copdis Rhizoma is a well-known medicial herb for its antiinflammatory, antimicrobial, and analgesic pharmacological activities. For external use, in traditional Chinese medicine Coptis Rhizome has shown effectiveness in treating burn, acne, skin ulcers, neurodermatitis and other types of eczema.

The purpose is different. A normal refluxing apparatus consists only of a flask and cooling above (so fumes are collected while boiling and you can keep the amount of solvent constant). Soxhlet extraction on the other hand is for separating parts that are soluble in a solvent. These devices allow for continuous treatment of a sample with a solvent over a period of hours or days to extract compounds of interest. Typically,

a Soxhlet extraction is only required where the desired compound has a limited solubility in a solvent, and the impurity is insoluble in that solvent. A rotary evaporator (or rotavap[1]/rotovap) is a device used in chemical laboratories for the efficient and gentle removal of solvents from samples by evaporation. When referenced in the chemistry research literature, description of the use of this technique and equipment may include the phrase "rotary evaporator", though use is often rather signaled by other language (e.g., "the sample was evaporated under reduced pressure"). think an additional question is what is the best solvent to extract phenols. My experience with soxhlet extraction of various factions in organic rich source rocks depended on the solvent ie. chloroform, benzene-methanol and xylene which resulted in different yields of certain organic fractions. The main difference in the apparatus is that sample that you are extracting is not immersed in the heated solvent, rather it is located in a glass microfiber soxhlet thimble placed in the soxhlet glassware above the round bottom which is filled with your solvent. The solvent boils and then condenses into the thimble. Key to note is that the solvent is not heated as it extracts the organics fom your sample. Eventually the thimble reservoir fills to an over flow arm which cyles the extract and solvent back down to the round bottom, and for the solvent to be boiled again. Check for the best solvent as either method would work, but extraction efficiency is more dependendet on solvent.

 A Soxhlet extractor is a piece of laboratory apparatus invented in 1879 by Franz von Soxhlet.[2] •

It was originally designed for the extraction of a lipid from a solid material.

Typically, Soxhlet extraction is used when the desired compound has a limited solubility in a solvent , and the impurity is insoluble in that solvent. •

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1.It allows for unmonitored and unmanaged operation while efficiently recycling a small amount of solvent to dissolve a larger amount of material.

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2. Soxhlet extraction is performed with different solvent mixtures such as hexane/dichloromethane, dichloromethane/light petroleum, cyclohexane/acetone or hexane/acetone, or even methanol, depending on the nature of the sample and the pesticides covered in the analytical method.

Soxhlet extraction procedure  First, the sample material is packed in filter paper and placed in the thimble.  Next, vapors of a fresh solvent, produced in a distillation flask, pass through the thimble containing the material to be extracted and are liquefied in the condenser.

 When the liquid reaches the overflow level in the thimble, a siphon aspirates the solution, and the liquid falls back into the distillation flask, carrying the extracted solutes into the bulk liquid. The separation of solute from solvent takes place in the distillation flask  Then solute is left in the flask and fresh solvent vapors pass back into the solid bed of sample material.  The operation is repeated until complete extraction is achieved.

Thin-Layer Chromatography  Chromatography is an important biophysical technique that enables the separation, identification, and purification of the components of a mixture for qualitative and quantitative analysis.  In this physical method of separation, the components to be separated are distributed between two phases, one of which is stationary (stationary phase) while the other (the mobile phase) moves in a definite direction.  Thin- layer chromatography is a method of separation or identification of a mixture of components into individual components by using finely divided adsorbent solid / (liquid) spread over a plate and liquid as a mobile phase.

Principle of Thin Layer Chromatography (TLC)  Performed on a sheet of glass, plastic, or aluminium foil, which is coated with a thin layer of adsorbent material, usually silica gel, aluminium oxide (alumina), or cellulose. This layer of adsorbent is known as the stationary phase  After the sample has been applied on the plate, a solvent or solvent mixture (known as the mobile phase) is drawn up the plate via capillary action. Because different analytes ascend the TLC plate at different rates, separation is achieved.  Once separation occurs, the individual components are visualized as spots at a respective level of travel on the plate. Their nature or character is identified by means of suitable detection techniques. Components of Thin Layer Chromatography (TLC)  TLC Plates – ready-made plates are used which are chemically inert and stable. The stationary phase is applied on its surface in the form of a thin layer. The stationary phase on the plate has a fine particle size and also has a uniform thickness.  TLC Chamber – used to develop plates. It is responsible to keep a steady environment inside which will help in developing spots. Also, it prevents the solvent evaporation and keeps the entire process dust-free.

 TLC Mobile phase – The one that moves and consists of a solvent mixture or a solvent. This phase should be particulate-free. The higher the quality of purity the development of spots is better.  TLC Filter Paper – It has to be placed inside the chamber. It is moistened in the mobile phase Procedure of Thin-Layer Chromatography (TLC)  The stationary phase that is applied to the plate is made to dry and stabilize.  To apply sample spots, thin marks are made at the bottom of the plate with the help of a pencil.  Apply sample solutions to the marked spots.  Pour the mobile phase into the TLC chamber and to maintain equal humidity, place a moistened filter paper in the mobile phase.  Place the plate in the TLC chamber and close it with a lid. It is kept in such a way that the sample faces the mobile phase.  Immerse the plate for development. Remember to keep the sample spots well above the level of the mobile phase. Do not immerse it in the solvent.  Wait till the development of spots. Once the spots are developed, take out the plates and dry them. The sample spots can be observed under a UV light chamber.

Rf value is the ratio of distance travelled by a substance to distance travelled by a solvent front. Higher the Rf value lesser the polarity of the substance. Lower the Rf value higher is the polarity of the substance.

Advantages of Thin Layer Chromatography  Simple process with a short development time  Helps with the visualization of separated compound spots easily  Helps in isolating of most of the compound  Separation process is faster and the selectively for compounds is higher  Purity standards of the given sample can be assessed easily  Cheaper chromatographic technique

Disadvantages Of Thin Layer Chromatography  Thin Layer Chromatography plates do not have longer stationary phase.  When compared to other chromatographic techniques the length of separation is limited.  The results generated from TLC are difficult to reproduce.  Since TLC operates as an open system, some factors such as humidity and temperature can be consequences to the final outcome of the chromatogram.  The detection limit is high and therefore if you want a lower detection limit, you cannot use TLC.  It is only a qualitative analysis technique and not quantitative. Types Of Chromatography  Column chromatography  Is a chromatography method used to isolate a single chemical compound from a mixture  Chromatography is able to separate substances based on differential adsorption of compounds to the adsorbent; compounds move through the column at different rates, allowing them to be separated into fractions.  The technique is widely applicable, as many different adsorbents can be used with a wide range of solvents.  The technique can be used on scales from micrograms up to kilograms. The main advantage of column chromatography is the relatively low cost and disposability of the stationary phase used in the process.  Column chromatography preparation  A column is prepared by packing a solid absorbent into a cylindrical glass or plastic tube.  The size will depend on the amount of compound being isolated. The base of the tube contains a filter, either a cotton or glass wool plug, or glass frit to hold the solid phase in place. A solvent reservoir may be attached at the top of the column.  For the dry method, the column is first filled with dry stationary phase powder, followed by the addition of mobile phase, which is flushed through the column until it is completely wet, and from this point is never allowed to run dry.  For the wet method, a slurry is prepared of the eluent with the stationary phase powder and then carefully poured into the column. The top of the silica should be flat, and the top of the

silica can be protected by a layer of sand. Eluent is slowly passed through the column to advance the organic material.  The individual components are retained by the stationary phase differently and separate from each other while they are running at different speeds through the column with the eluent.  At the end of the column they elute one at a time. During the entire chromatography process the eluent is collected in a series of fractions. Fractions can be collected automatically by means of fraction collectors.  The productivity of chromatography can be increased by running several columns at a time. In this case multi stream collectors are used. The composition of the eluent flow can be monitored and each fraction is analyzed for dissolved compounds, e.g. by analytical chromatography, UV absorption spectra, or fluorescence.  Colored compounds (or fluorescent compounds with the aid of a UV lamp) can be seen through the glass wall as moving bands.  High Performance Liquid Chromatography (HPLC)  Widely used for the analysis of antibiotics  A modern application of liquid chromatography  Guarantees a high sensitivity and, at the same time, this technique has its gas analogue.  The principle of HPLC is the same as that of liquid chromatography (LC), liquid–solid chromatography (LSC) and liquid–liquid chromatography (LLC).  Is a useful method for quinolizidine alkaloid analysis, especially when pure standards are available  This method was recently used for alkaloid metabolite extraction and analysis  Gas chromatography  an analytical technique used to separate and analyze samples that can be vaporized without thermal decomposition.  known as gas-liquid partition chromatography (GLPC) or vapor-phase chromatography (VPC).  The instrument that performs gas chromatography is called a gas chromatograph.  The resulting graph that shows the data is called a gas chromatogram.  Used as one test to help identify components of a liquid mixture and determine their relative concentration  Used to separate and purify components of a mixture.  Used to determine vapor pressure, heat of solution, and activity coefficients.

 Paper Chromatography  Chromatography technique that uses paper sheets or strips as the adsorbent being the stationary phase through which a solution is made to pass is called paper chromatography.  An inexpensive method of separating dissolved chemical substances by their different migration rates across the sheets of paper.  Powerful analytical tool that uses very small quantities of material.  Ion exchange chromatography  Is a process that allows the separation of ions and polar molecules based on their affinity to the ion exchanger.  Used for almost any kind of charged molecule including large proteins, small nucleotides, and amino acids.  Cationic exchangers possess negatively charged groups, and these will attract positively charged cations. These exchangers are also called “Acidic ion exchange” materials because their negative charges result from the ionization of acidic groups.  Anionic exchangers have positively charged groups that will attract negatively charged anions. These are also called “Basic ion exchange” materials.  Size exclusion chromatography  A chromatographic technique used for separating substances according to their molecular size, or more correctly, hydrodynamic volume.  Separates molecules based on their size by filtration through a gel. The gel consists of spherical beads containing pores of a specific size distribution.  Desalting — A common use of SEC is for desalting protein or nucleic acid samples. The molecule of interest is eluted in the void volume, while smaller molecules are retained in the gel pores.  Fractionation — Molecules of varying molecular weights are separated within the gel matrix. With this separation method, the molecules of interest should fall within the fractionation range of the gel  Supercritical fluid chromatography  Is a rapidly developing laboratory technique for the separation and identification of compounds in mixtures.  A form of normal phase chromatography that uses a supercritical fluid such as carbon dioxide as the mobile phase.

 It is used for the analysis and purification of low to moderate molecular weight, thermally labile molecules and can also be used for the separation of chiral compounds.  High-performance thinlayer chromatography (HPTLC)  An enhanced form of thin-layer chromatography (TLC).  Is employed widely in pharmaceutical industries for process development, identification, and detection of adulterants in herbal products; identification of pesticide content and mycotoxins; and in quality control of herbs and health food.  Liquid chromatography-Mass spectroscopy  Widely used method of sample ionization prior to analysis and is frequently coupled with mass spectrometry.  An analytical chemistry technique that combines the physical separation capabilities of liquid chromatography (or HPLC) with the mass analysis capabilities of mass spectrometry (MS)....