Separation Techniques, Fibres, and Dressing

Questions and Answers

What is a desirable characteristic of an ideal solvent for extraction?

High toxicity to humans and the environment

High cost

High reactivity with the extracted compound

High selectivity for the compound to be extracted (correct)

Which of the following is a disadvantage of using water as a solvent?

It is expensive

It is not readily available

It is a good solvent for many plant constituents

It easily extracts undesirable components such as sugars and gums (correct)

What is a characteristic of the plant constituents that are easily extracted by water?

They are desirable components

They are less soluble in water

They are highly soluble in water (correct)

They are complex organic chemicals

Why may preservatives need to be added to aqueous preparations?

To prevent the growth of molds, yeasts, and bacteria Signup and view all the answers

What type of compounds does alcohol dissolve?

Alkaloids, alkaloid salts, glycosides, and volatile oils Signup and view all the answers

What is a characteristic of the compounds that are not dissolved by alcohol?

They are albuminous matter, gums, waxes, fats, and fixed oils Signup and view all the answers

Why is a high amount of heat needed to concentrate an aqueous extraction?

Because water has a high boiling point Signup and view all the answers

What is an advantage of using water as a solvent?

It is readily available and cheap Signup and view all the answers

What is a common use of alcohol as a solvent?

To extract alkaloids, alkaloid salts, and glycosides Signup and view all the answers

What is the minimum concentration of alcohol required to prevent microbial contamination in an alcohol solution?

20% Signup and view all the answers

What is the primary advantage of using infusions for soft drugs?

Water can penetrate easily into the tissues Signup and view all the answers

What is the main disadvantage of using decocations for extraction?

Not suitable for soft drugs Signup and view all the answers

What is the purpose of stirring during the infusion process?

To ensure uniform extraction Signup and view all the answers

Why is boiling water commonly used as a solvent in infusion?

It is a polar solvent Signup and view all the answers

What is the primary advantage of using ABBA Anas?

Non-toxic Signup and view all the answers

What type of crude drugs are typically extracted using decocations?

Hard and woody drugs Signup and view all the answers

What is the duration of the infusion process?

3-7 minutes Signup and view all the answers

What is the result of the infusion process?

A liquid Signup and view all the answers

What is the primary purpose of boiling the crude drug with water in the extraction process?

To increase the solubility of the drug Signup and view all the answers

What type of equipment is used in the digestion process of extraction?

Pressure cooker or autoclave Signup and view all the answers

What is the main advantage of using digestion over other extraction methods?

Improved solubilisation rate of soluble matters Signup and view all the answers

What type of maceration process is used for tinctures made from unorganised drugs?

Maceration with adjustment Signup and view all the answers

What is the purpose of shaking the mixture in the simple maceration process?

To facilitate the solubilisation of the drug Signup and view all the answers

What is the typical duration of the simple maceration process?

7 days Signup and view all the answers

What is the purpose of pressing the marc in the simple maceration process?

To increase the yield of the extracted material Signup and view all the answers

What type of solvent is typically used in the simple maceration process?

Concentrated alcohol Signup and view all the answers

What is the purpose of using a closed vessel in the simple maceration process?

To prevent the evaporation of the menstruum Signup and view all the answers

What is the primary difference between simple distillation and fractional distillation?

The equipment used in the process Signup and view all the answers

Which separation technique is based on the difference in physical properties of the components?

All of the above Signup and view all the answers

What is the purpose of the glass beads in a fractionating column?

To increase the surface area for condensation Signup and view all the answers

What is the term for the process of a substance changing directly from a solid to a gas?

Sublimation Signup and view all the answers

Which of the following is an example of a substance that sublimes on heating?

Iodine Signup and view all the answers

What is the purpose of using an inverted funnel in the sublimation process?

To collect the sublimed substance Signup and view all the answers

Which separation technique is used to separate a mixture of a soluble substance and a solvent?

Simple distillation Signup and view all the answers

What is the main limitation of the sublimation process?

Very few solids will sublime on heating Signup and view all the answers

What is the purpose of decantation in separating a mixture?

To separate a liquid from an insoluble solid Signup and view all the answers

What is the principle behind fractional distillation?

Differences in boiling points Signup and view all the answers

Which of the following is an example of a product obtained through crystallization?

Rocky candy Signup and view all the answers

What happens to the dissolved substance during crystallization?

It comes out of solution and collects as crystals Signup and view all the answers

What is the primary basis for separation in chromatography?

Differences in ability to be drawn across a surface Signup and view all the answers

What happens to the components with the strongest attraction for the paper in chromatography?

They travel the slowest Signup and view all the answers

What is the result of evaporation in crystallization?

The dissolved substance comes out of solution Signup and view all the answers

Which separation technique is used to separate ethanol from glucose solution?

Fractional distillation Signup and view all the answers

What is the purpose of fractional distillation in the separation of crude oil?

To separate different components of crude oil Signup and view all the answers

What is the result of fractional distillation of liquid air?

Separation of oxygen and nitrogen Signup and view all the answers

What is the primary function of a menstruum in extraction?

To dissolve the medicinally active constituents Signup and view all the answers

Which of the following solvents is considered polar?

Acetone Signup and view all the answers

What is the result of the extraction process?

The separation of medicinally active portion from the inactive components Signup and view all the answers

What is the advantage of using a polar solvent?

It is more selective in dissolving certain compounds Signup and view all the answers

What is the purpose of evaporation in the preparation of extractives?

To remove the solvent from the extract Signup and view all the answers

Which of the following is a characteristic of non-polar solvents?

They have a dielectric constant less than 15 Signup and view all the answers

What is the term for the concentrated preparation of vegetable or animal drugs obtained by removal of the active constituents?

Extractives Signup and view all the answers

What is the primary purpose of the 'extractive solvent' in liquid-liquid extraction?

To bring about the transfer of one or more solute into the first solvent Signup and view all the answers

What is the main characteristic of solid-liquid extraction?

Separation of soluble constituents from a solid by extraction with a solvent Signup and view all the answers

What is the primary purpose of galenicals?

To convert crude extracts into dry extracts Signup and view all the answers

What is the main difference between tinctures and galenicals?

Tinctures are prepared from vegetable material, while galenicals are prepared from animal tissues Signup and view all the answers

What is the primary advantage of using liquid-liquid extraction?

It is a selective method that separates compounds based on their relative solubilities Signup and view all the answers

What is the primary purpose of menstruum in extraction?

To extract the soluble constituents from the solid Signup and view all the answers

What is the primary characteristic of expression as a method of fragrance extraction?

It involves the compression of raw materials to extract the oils Signup and view all the answers

Which of the following extraction methods involves the use of heat and pressure?

Digestion Signup and view all the answers

What is the primary purpose of using a closed vessel in the simple maceration process?

To prevent evaporation of the menstruum Signup and view all the answers

Which type of solvent is most suitable for extracting thermolabile compounds?

Cold Water Signup and view all the answers

What is the primary advantage of using digestion over other extraction methods?

It is more efficient in extracting non-thermolabile compounds Signup and view all the answers

Which of the following is NOT a type of maceration process?

Distillation Signup and view all the answers

What is the purpose of pressing the marc in the simple maceration process?

To separate the liquid from the solid Signup and view all the answers

What is the primary purpose of shaking the mixture during the simple maceration process?

To mix the drug and menstruum thoroughly Signup and view all the answers

Which type of maceration process is used for tinctures made from unorganised drugs, where the final volume is made up by passing the remaining menstruum through the filter?

Maceration with adjustment Signup and view all the answers

What is the primary purpose of percolation process?

To extract the maximum amount of active ingredients from the drug Signup and view all the answers

What is the purpose of shaking the mixture in the simple maceration process?

To mix the solvent and solute thoroughly Signup and view all the answers

What is the primary difference between multiple maceration and maceration with adjustment?

The final volume adjustment Signup and view all the answers

What type of percolator is used for tinctures and other preparations?

All of the above Signup and view all the answers

What is the primary advantage of using multiple maceration over simple maceration?

It increases the extraction of active ingredients Signup and view all the answers

What is the primary purpose of the filter in the tincture preparation process?

To remove impurities from the tincture Signup and view all the answers

What is the primary advantage of using infusions for soft drugs?

It allows for easy penetration of water into the tissues of the drug Signup and view all the answers

Which of the following is NOT an advantage of using alcohol as a solvent?

It is easily available at a low cost Signup and view all the answers

What is the primary purpose of decocations?

To extract heat-stable and water-soluble constituents from hard and woody crude drugs Signup and view all the answers

What is the minimum concentration of alcohol required to prevent microbial contamination in an alcohol solution?

20% Signup and view all the answers

What is the result of the infusion process?

A liquid extract Signup and view all the answers

What is the primary function of a menstruum in extraction?

To dissolve and extract the active constituents from the drug Signup and view all the answers

What is the primary advantage of using alcohol as a menstruum?

It is non-toxic and dissolves selected active constituents of drugs Signup and view all the answers

Which of the following is a crucial consideration when selecting a solvent for extraction?

The solvent's ability to extract desirable compounds selectively Signup and view all the answers

What is the primary reason why water is not an ideal solvent for extracting active plant constituents?

Most active plant constituents are less soluble in water Signup and view all the answers

Alcohol is a good solvent for which of the following compounds?

Alkaloids, alkaloid salts, glycosides, and volatile oils Signup and view all the answers

What is the primary advantage of using a solvent with high selectivity?

It minimizes the extraction of unwanted compounds Signup and view all the answers

Which of the following is a characteristic of a good menstruum?

It is readily available and harmless to humans and the environment Signup and view all the answers

What is the primary reason why preservatives are added to aqueous preparations?

To prevent microbial contamination Signup and view all the answers

Which of the following is a disadvantage of using water as a solvent?

It serves as an excellent growth medium for microorganisms Signup and view all the answers

What is the primary purpose of heating during the extraction process?

To increase the solubility of the desired compounds Signup and view all the answers

Which of the following is a characteristic of the compounds extracted by alcohol?

They are typically complex organic compounds Signup and view all the answers

What is the primary advantage of using a solvent with high capacity for extraction?

It increases the yield of the extracted compound Signup and view all the answers

Study Notes

Liquid-Liquid Extraction

Ideal solvents for extraction should be highly selective, have high capacity, not react with the compound or other plant material, be inexpensive, and harmless to humans and the environment.
Commonly used solvents include water, ether, alcohol, and chloroform.

Advantages of Water as a Solvent

Readily available and inexpensive
Good solvent action for many plant constituents
Can be used with other solvents

Disadvantages of Water as a Solvent

Many active plant constituents are less soluble in water
Water can extract undesirable components like sugars, gums, and tannins
Aqueous preparations can support microbial growth, requiring preservatives like alcohol
Requires a large amount of heat to concentrate the extraction

Alcohol as a Solvent

Solvent for alkaloids, glycosides, volatile oils, and resins
Dissolves many forms of coloring matter, tannins, and organic acids and salts
Does not dissolve albuminous matter, gums, waxes, fats, or sugars

Advantages of Alcohol as a Solvent

No microbial contamination in solutions with 20% or more concentration
Requires minimal heat to concentrate the preparation
Non-toxic and dissolves selected active constituents of drugs

Disadvantages of Alcohol as a Solvent

Expensive
Flammable

Extraction Processes

Infusion

Process of extracting chemical compounds or flavors from plant material in a solvent
Involves steeping the material in the solvent, then filtering off the liquid
Used for soft drugs with water-soluble active constituents

Decoction

Process of extracting water-soluble and heat-stable constituents from hard and woody crude drugs
Involves boiling the drug in water for a specified time

Concoction

Process of heating a mixture of two or more drugs for a specified period

Digestion

Process using heat and pressure for extraction
Involves using equipment like a pressure cooker or autoclave
Efficient for extracting non-thermolabile materials due to high pressure and temperature

Maceration

Various types include simple maceration, maceration with adjustment, and double and triple maceration
Simple maceration involves mixing the drug with a menstruum, allowing it to stand for 7 days, then straining and pressing the liquid

General Separation Techniques

Decantation

Involves pouring off the upper liquid layer to separate a liquid from an insoluble solid

Filtration

Uses a porous barrier to separate a solid from a liquid
Liquid passes through, leaving the solid in the filter paper

Sublimation

Process of separating a solid that sublimes on heating from another substance with a high melting point
Limited uses, as very few solids will sublime on heating

Distillation

Used to separate homogeneous mixtures based on differences in boiling points
Types include simple distillation and fractional distillation

Crystallization

Technique that results in the formation of pure solid particles from a solution containing the dissolved substance
Produces highly pure solids

Chromatography

Separates components of a mixture based on their ability to be drawn across the surface of another material
Components with the strongest attraction for the material travel the slowest

Extraction Processes

Tinctures: Alcoholic or hydroalcoholic solutions prepared from vegetable material or chemical substances (e.g. belladonna tincture)
Expression: A method of fragrance extraction where raw materials are pressed, squeezed, or compressed, and the oils are collected
Galenicals: Extracts initially obtained by leaching vegetables or animal tissues with suitable solvents, concentrated, and converted into dry extracts
Some extraction products include:
- Fixed oils from seeds
- Alkaloids (e.g. quinine from Cinchona bark)
- Morphine from opium
- Reserpine from Rauvolfia serpentina

Classification of Extraction

Solid-Liquid Extraction (Leaching):
- Separation of soluble constituents from a solid by extraction with a solvent
- Two stages: contact of solute with the liquid phase, and separation of the liquid phase from the solid phase
Liquid-Liquid Extraction (Solvent Extraction or Partitioning):
- Separation of compounds based on their relative solubilities in two different immiscible liquids (usually water and an organic solvent)
- Performed using a separatory funnel, where an extractive solvent is brought into contact with a solute-bearing solvent

Definitions

Extraction: Treatment of plant or animal tissues with a solvent to dissolve medicinally active constituents, leaving behind inert matter
Menstruum: Solvent used for extraction (e.g. water, alcohol, ether, acetone, etc.)
Marc: Inert, fibrous, and insoluble materials remaining after extraction
Extractives: Concentrated preparations of vegetable or animal drugs obtained by removal of active constituents with a suitable menstruum and evaporation of the solvent

Maceration with Adjustment

Unorganised drug is placed with 4/5th of menstruum in a closed vessel for 2-7 days
Shaking is done occasionally
Liquid is filtered, and the final volume is made up by passing the remaining 1/5th of the menstruum through the filter

Multiple Maceration

Used to establish maximum extraction by dividing the total quantity of menstruum into multiple macerations
Repeating the process 2-4 times to make the extraction process more effective

Percolation

Continuous flow of a solvent through a bed of drug material to obtain the extract
Types of percolation:
- Simple percolation for tinctures
- Reserve percolation process
- Modified percolation process
- Continuous hot percolation or soxhelation
Apparatus used: Conical Percolator, Cylindrical Percolator, Stem jacketed percolator

Concoction

Heating a mixture of two or more drugs for a specified period of time

Digestion

Using heat and pressure to extract non-thermolabile materials
Equipment used: Pressure cooker or autoclave (called a digester)

Maceration

Various types of maceration processes:
- Simple Maceration for tinctures made from organized drugs (e.g. roots, stems, leaves)
- Maceration with adjustment for unorganised drugs (e.g. oleo resins and gum resins)
- Double and triple maceration process for concentrated preparations

Advantages and Disadvantages of Solvents

Advantages of water as a solvent:
- Readily available
- Cheap
- Good solvent action for many plant constituents
- Can be used with other solvents
Disadvantages of water as a solvent:
- Most active plant constituents are less soluble in water
- Plant constituents like sugars, gums, starches, and tannins are easily extracted but may interfere with clarity of preparations
- Aqueous preparations serve as an excellent growth medium for microorganisms
Advantages of alcohol as a solvent:
- Solvent for alkaloids, alkaloid salts, glycosides, volatile oils, and resins
- Does not dissolve albuminous matter, gums, waxes, fats, and sugars
Disadvantages of alcohol as a solvent:
- Costly
- Flammable

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Description

Learning about different separation techniques and extraction processes.