Pharmacognosy: Separation and Isolation of Plant Constituents
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Questions and Answers

What is considered the most difficult operation in phytochemical research?

  • Identification of bioactive compounds
  • Purification of materials present in a crude extract
  • Isolation and purification of plant constituents (correct)
  • Separation of volatile mixtures

What is the primary purpose of exploiting chemical properties of functional groups in phytochemical research?

  • To separate components of the same class
  • To purify materials present in a crude extract
  • To isolate bioactive compounds
  • To separate compounds from other materials (correct)

What is employed in modern sublimation equipment?

  • Variable pressures with a loose control of temperature
  • Room pressure with a moderate control of temperature
  • High pressures with a strict control of temperature
  • Low pressures with a strict control of temperature (correct)

What is the traditional use of fractional distillation in phytochemistry?

<p>Separation of the components of volatile mixtures (D)</p> Signup and view all the answers

What is the limitation of exploiting chemical properties of functional groups in phytochemical research?

<p>It might not fractionate components of the same class (D)</p> Signup and view all the answers

What is the application of sublimation in phytochemical research?

<p>Isolation of caffeine from tea (C)</p> Signup and view all the answers

What is a common challenge when using the traditional method of separating and isolating constituents on a laboratory scale?

<p>Separating minor components of a mixture in a pure state (A)</p> Signup and view all the answers

What is the purpose of shaking the mixture with an organic solvent after each addition of alkali in fractional liberation?

<p>To obtain a fractionated series of bases (C)</p> Signup and view all the answers

What is the principle behind fractional crystallization?

<p>Differences in solubility of the components in a particular solvent (B)</p> Signup and view all the answers

What is the purpose of forming derivatives of the components in fractional crystallization?

<p>To facilitate the separation of the components (D)</p> Signup and view all the answers

What is the outcome of treating a mixture of alkaloid salts with alkali in fractional liberation?

<p>The weakest base is liberated first (A)</p> Signup and view all the answers

What is the role of mineral acids in the fractional liberation of organic acids?

<p>To fractionally liberate the acids (C)</p> Signup and view all the answers

What is the fundamental principle of adsorption chromatography?

<p>Selective adsorption of substances on the surface of finely divided solids (C)</p> Signup and view all the answers

What is the purpose of using charcoal in solutions?

<p>To decolorize and clarify solutions (B)</p> Signup and view all the answers

What is the role of the calcium carbonate column in Tswett's experiment?

<p>To separate and isolate the pigments based on their adsorption properties (C)</p> Signup and view all the answers

Which pigments are more strongly adsorbed in Tswett's experiment?

<p>Xanthophyll and the chlorophylls (B)</p> Signup and view all the answers

What is the result of the pigments undergoing separation as percolation proceeds?

<p>Distinct, characteristically coloured bands of pigments (B)</p> Signup and view all the answers

Why do the carotenes accumulate lower down in the column?

<p>Because they are less strongly adsorbed than the chlorophylls (D)</p> Signup and view all the answers

What is the primary purpose of allowing more of the pure solvent to percolate through the column?

<p>To separate the constituents into distinct bands (B)</p> Signup and view all the answers

What is the effect of using a different solvent in the chromatography process?

<p>The substances are less strongly adsorbed (C)</p> Signup and view all the answers

What happens to the lower bands as percolation continues?

<p>They reach the bottom of the column and disappear (B)</p> Signup and view all the answers

What is the term used to describe the process of desorption?

<p>Elution (C)</p> Signup and view all the answers

What is the solution obtained after the process of elution?

<p>Eluate (B)</p> Signup and view all the answers

Who is credited with the development of the term 'chromatography'?

<p>Tswett (C)</p> Signup and view all the answers

Flashcards

Gas Chromatography

A technique used for separating and analyzing compounds in a mixture.

Fractional Liberation

Treating a mixture with acid/base to separate constituents in order.

Alkaloid Salts

Water-soluble compounds obtained from plants, often separated using solvents.

Fractional Crystallization

Separation method using solubility differences in a solvent.

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Solubility

The ability of a substance to dissolve in a solvent.

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Picrate Derivatives

Compounds formed to assist in the separation of alkaloids.

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Adsorption Chromatography

Technique to separate substances based on adsorption properties.

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Selective Adsorption

The preferential adherence of substances onto solid surfaces.

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Calcium Carbonate

A commonly used adsorbent in adsorption chromatography.

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Percolation

The process of a solution passing through a porous substance.

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Sublimation

Method to isolate pure materials by converting a solid directly to gas.

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Distillation

Separation method for volatile components by boiling and condensing.

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Fractional Distillation

A refined distillation process for separating mixtures with different boiling points.

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Volatile Oils

Organic compounds that easily evaporate at room temperature.

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Elution

The process of desorbing adsorbed materials from a column.

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Efficiency in Chromatography

Improving separation by changing solvents and percolation methods.

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Adsorbed Materials

Substances attached to the surface of a solid in chromatography.

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Distinct Bands

Separated layers of materials observed during chromatography.

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Desorption

The removal of adsorbed substances from a solid.

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Organic Solvent

A solvent composed of carbon-containing compounds, used to separate substances.

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Crude Extract

An unrefined extract from plant materials containing various components.

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Solvent Characteristics

Properties of solvents that affect their ability to separate components.

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Components of Mixture

Individual constituents in a blend that can be separated.

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Plant Constituents

Chemical compounds found in plants that can be isolated for study.

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Separation Techniques

Methods employed to isolate specific constituents from a mixture.

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Study Notes

Separation and Isolation of Constituents

  • Separation and isolation of minor components of a mixture are challenging on a laboratory scale, and gas chromatography is often used instead.
  • Fractional liberation involves treating a mixture with a base or acid to liberate constituents in a specific order, and then separating them using an organic solvent.
  • This method is useful for separating alkaloid salts and organic acids soluble in water-immiscible solvents.

Fractional Crystallization

  • Fractional crystallization is a traditional method that exploits differences in solubility of mixture components in a particular solvent.
  • Derivatives of the components, such as picrates of alkaloids or osazones of sugars, are often used to facilitate separation.

Adsorption Chromatography

  • Adsorption chromatography is a technique that separates and isolates plant constituents based on selective adsorption.
  • Finely divided solids have the power to adsorb other substances on their surfaces, and this phenomenon is the fundamental principle of adsorption chromatography.
  • The method involves allowing a solution to percolate through a column of a substance, such as powdered calcium carbonate, and separating the components based on their adsorption strengths.

Sublimation and Distillation

  • Sublimation is a method that can be used to isolate and purify plant constituents, often employed on the whole drug or for the purification of materials present in a crude extract.
  • Distillation, particularly fractional distillation, has been widely used for the separation of volatile mixtures, including the components of volatile oils.

Development of Chromatography

  • The process of adsorption chromatography can be developed by allowing more of the pure solvent to percolate through the column, causing the adsorbed materials to slowly pass downwards and separate into distinct bands.
  • Using a different solvent, one from which the substances are less strongly adsorbed, can also improve the efficiency of the process.
  • The process of desorption, termed elution, can be used to obtain the separated pigments in a solution.

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Pharmacognosy: Separation and Isolation of Constituents PDF

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Test your knowledge on the separation and isolation techniques of plant constituents in phytochemical research, including sublimation, distillation, and chromatography. Learn how to purify and isolate plant compounds with these essential methods.

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