modern methods of extraction???

Modern Methods of Extraction???

Eco friendly Non toxic Fast and automated Highly sensitive Robust Cost Efficient

P512 Pharmacognosy and PhytochemistryII Unit 4 Extraction

Super critical fluid extraction (SFE)

Super critical fluid extraction (SFE) is the process of extraction in which , super critical fluid is used as extraction solvent. an alternative sample preparation method with general goals of reduced use of organic solvents and increased sample throughput.

A fluid at supercritical condition, also referred to as a dense gas, is a fluid above its critical temperature (TC) and critical pressure (PC) to a certain extent: to be supercritical. Critical temperature(Tc) is the highest temperature at which gas can be converted to liquid by an increase in pressure Critical pressure(Pc) is the highest pressure at which liquid can be converted to gas by an increase in temperature The critical point of a pure substance is the highest temperature and pressure at which the substance can exists in vapour –liquid equilibrium. Supercritical fluids combine useful properties of gas and liquid phases, as it can behave like both a gas and a liquid in terms of different aspects.


•The motion of the molecules are quite similar to gas molecules. •On the other hand, a supercritical fluid behaves like a liquid because its density property is near liquid and, thus, a supercritical fluid shows a similarity to the dissolving effect of a liquid.

almost the same as a gas, being approximately 1/10 of that of a liquid.

supercritical fluids are less resistant than liquids towards components flowing through

Diffusivity of a supercritical fluid can be 100 x that of a liquid and 1/1000 to 1/10000 x less than a gas. Because supercritical fluids have more diffusivity than a liquid, it stands to reason a solute can show better diffusivity in a supercritical fluid than in a liquid. Increasing pressure affects supercritical fluid molecules to become closer to each other and decreases diffusivity in the material.

Diffusivity

supercritical fluid is between that of a gas and a liquid, but closer to that of a liquid. density of a supercritical fluid increases with increased pressure (at constant temperature). When pressure is constant, density of the material decreases with increasing temperature.

Density

Viscosity

Properties of supercritical fluids


Critical Temperature and pressure of some solvents

Solvent Critical Temperature (°C)

Critical Pressure (bar)

Carbon dioxide (CO2) 31.1 72

Nitrous oxide (N2O) 36.5 70.6

Ammonia (NH3) 132.5 109.8

Ethane (C2H6) 32.3 47.6

n-Butane (C4H10) 152 70.6 P512 Pharmacognosy and PhytochemistryII

Unit 4 Extraction

scCO2 • SC-C02 is attractive as extraction medium

because of its high diffusivity

• combined with its high (and easily tunable) solvent strength.

• Another advantage of SC-C02 is that it is gaseous at room temperature and ambient pressure, which makes product (or analyte) recovery fairly simple.

• Furthermore, the C02 can be easily recycled as the solutes dissolved in the SC-C02 will precipitate upon depressurization.


Instrumentation


Modes of Instrument run: • There are two principle modes to run the instrument:

• Static extraction

• Dynamic extraction

• In dynamic extraction, the second pump sending the materials out to the collection chamber is always open during the extraction process. Thus, the mobile phase reaches the extraction cell and extracts components in order to take them out consistently.

• In the static extraction experiment, there are two distinct steps in the process:

1. The mobile phase fills the extraction cell and interacts with the sample.

2. The second pump is opened and the extracted substances are taken out at once.


SFE Bio-Botanical Extraction System®


Parameter to be considered • temperature and pressure of the SF • extraction time • flow rate • addition of cosolvent (type of solvent and

amount) • collection mode (e.g. in a solvent, in an empty

vessel or on a solid-phase trap).

• The solubility of the substance of interest • The selectivity of this substance with respect to

others that are extracted simultaneously • The way to separate the substance of interest

from the total extract


Advantages

• The extraction of constituents at low temperature, which strictly avoids damage from heat and some organic solvents.

• No solvent residues.

• Environmentally friendly extraction procedure.


Application

Plant name (part used)

Product(s) extracted Reference

Calendula officinalis (fl owers)

Oleoresin Campos et al., 2005;Danielski et al., 2007,

Ginkgo biloba (leaves)

Flavonol glycosides (fl avonoids) and terpenoids

Chun Yang et al., 2002,

Eucalyptus spp. (leaves)

Essential oil Della Porta, et al., 1999,

Hypericum perforatum (herb)

Naphthodianthones, hypericin and pseudohypericin

Catchpole et al., 2002

Saccharum spp. (crude wax)

Long chain n-alcohols De Lucas et al., 2005,

Taxus brevifolia (bark)

Taxol Jennings et al., 1992,

extraction of

•pesticides

•environmental samples

•foods and fragrances

•essential oils

• polymers and natural products.


Instrumentation


modern methods of extraction???

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