Extraction Technologies for Medicinal and Aromatic ... - Capacity4Dev
Extraction Technologies for Medicinal and Aromatic ... - Capacity4Dev
Extraction Technologies for Medicinal and Aromatic ... - Capacity4Dev
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12 FLASH CHROMATOGRAPHY AND LOW PRESSURE CHROMATOGRAPHIC TECHNIQUES FOR SEPARATION OF PHYTOMOLECULES<br />
• Collect the aliquot in the vial in position 2 of the collection<br />
rack.<br />
• Continue until all the components of interest have been collected.<br />
Alternatively, multiple columns can be processed by replacing<br />
collection vials at each elution step. A typical volume <strong>for</strong> each fraction is<br />
two CV.<br />
12.7.2 On-line Flash Chromatography<br />
Using an automated system equipped with a fraction collector,<br />
fractions can be collected in a variety of ways, <strong>for</strong> example:<br />
• Fixed volume fraction collection.<br />
• Individual peak fraction collection under microprocessor<br />
control with UV detector input.<br />
12.8 Low Pressure Liquid Chromatography<br />
In low pressure column chromatography, a column of particulate<br />
material such as silica or alumina has a solvent passed through it at<br />
atmospheric or low pressure. There are different kinds of low pressure chromatographic<br />
techniques:<br />
i) Gel fi ltration chromatography (separation on the basis of<br />
size)<br />
ii) Ion exchange chromatography (separation of the basis of<br />
charge)<br />
iii) Affi nity chromatography (separation on the basis of specifi c<br />
binding sites on the proteins)<br />
12.8.1 Gel Filtration Chromatography<br />
Proteins of different sizes are separated on a column in which<br />
the stationary phase consists of polymerized agarose or acrylamide beads<br />
with pores of particular sizes. A small protein in the mobile phase (aqueous<br />
buffered solution) can enter the pores in the beads while a large protein<br />
cannot due to size restriction. The result is that a smaller fraction of the<br />
overall volume of the column is available to the large protein than to the<br />
small protein, which thus spends a longer time on the column <strong>and</strong> is eluted<br />
by the mobile solvent after the large protein.<br />
12.8.2 Ion Exchange Chromatography<br />
The material used <strong>for</strong> this type of chromatography consists of<br />
an agarose, acryl amide or cellulose resin or bead which is derivatized to<br />
contain covalently linked positively or negatively charged groups. Proteins<br />
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