4solid Phase Extraction Techniques Ppt

7/22/2019 4solid Phase Extraction Techniques Ppt

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A Soxhlet extractor is a piece of laboratory

apparatus invented in 1879 by Franz von Soxhlet.It was originally designed for the extraction of alipid from a solid material. However, a Soxhletextractor is not limited to the extraction of lipids.

Typically, a Soxhlet extraction is only requiredwhere the desired compound has a limitedsolubility in a solvent, and the impurity is insoluble inthat solvent.

If the desired compound has a significant solubilityin a solvent then a simple filtration can be used toseparate the compound from the insolublesubstance.


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A schematic

representation of aSoxhlet extractor1: Stirrer bar 2: Still pot (thestill pot should not be

overfilled and the volumeof solvent in the still potshould be 3 to 4 times thevolume of the soxhletchamber) 3: Distillation

path4: Thimble 5: Solid 6:Siphon top 7: Siphon exit 8:Expansion adapter 9:

Condensor 10:Coolingwater in


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Fruit extraction in progress. The sample is placed in


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Normally a solid material containing some of thedesired compound is placed inside a thimblemade from thick filter paper, which is loaded into

the main chamber of the Soxhlet extractor.The Soxhlet extractor is placed onto a flaskcontaining the extraction solvent. The Soxhlet isthen equipped with a condenser.

The solvent is heated to reflux. The solvent vapour

travels up a distillation arm, and floods into thechamber housing the thimble of solid.

The condenser ensures that any solvent vapourcools, and drips back down into the chamber

housing the solid material.The chamber containing the solid material slowlyfills with warm solvent. Some of the desiredcompound will then dissolve in the warm solvent.


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When the Soxhlet chamber is almost full, thechamber is automatically emptied by a siphon sidearm, with the solvent running back down to thedistillation flask. This cycle may be allowed torepeat many times, over hours or days.During each cycle, a portion of the non-volatilecompound dissolves in the solvent. After manycycles the desired compound is concentrated inthe distillation flask.

The advantage of this system is that instead ofmany portions of warm solvent being passedthrough the sample, just one batch of solvent isrecycled.After extraction the solvent is removed, typically by

means of a rotary evaporator, yielding theextracted compound.The non-soluble portion of the extracted solidremains in the thimble, and is usually discarded


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THE SOXHLETEXTRACTORContinuousextraction of a

componentfrom a solidmixture.Boiling solvent

vapors rise upthrough thelarger side-arm


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Condensed drops

of solvent fall intothe porous cup,dissolving out thedesired

component froma solid mixture


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When the smallerside-arm fills to

overflowing, itinitiates asiphoning action


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The solvent,containing thedissolvedcomponent, issiphoned into theboiler below


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Residual solventthen drains out ofthe porous cup, asfresh solvent dropscontinue to fallinto the porous

cup


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. . . and the cycle

repeats . . .


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It should look

somethinglike THIS


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Laurence M. Harwood, Christopher J. Moody.Experimental organic chemistry: Principles andPractice (Illustrated edition ed.).pp. 122125.

ISBN 978-0632020171.

Soxhlet, F. Die gewichtsanalytische Bestimmungdes Milchfettes, Polytechnisches J. (Dingler's) 1879,232, 461

The Origin of the Soxhlet Extractor William B. JensenVol. 84 No. 12 December 2007

Journal of Chemical Education 1913

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4solid Phase Extraction Techniques Ppt