Most drugs are natural: collected from sources such as plants, minerals, animals etc. These drugs are extracted and refined. Then there are drugs which may be semi-synthetic, i.e. collected from natural sources and then chemically modified to make appropriate use of them. However, majority percentage these …show more content…
This makes the liquid boil at a lower temperature. Figure 5 DIstillation under Reduced Pressure
STEAM DISTILLATION
Steam distillation is a special type of distillation used for temperature sensitive materials like natural aromatic compounds which are insoluble in water, but volatile in steam. The non-volatile impurities are left behind in the flask. It once was a popular laboratory method for purification of organic compounds, but has become obsolete by vacuum distillation. Figure 6 Steam Distillation
EXTRACTION WITH A SOLVENT
The process of removing or separating a substance from its aqueous solution using a suitable organic solvent is called extraction. It relies on variations in the solubility of different compounds in different substances. This method is widely used in the industry, and in the laboratory for refining, isolating and purifying a variety of useful compounds. Figure 7 …show more content…
Examples of some preparative chromatographic techniques include:
• Thin Layer Chromatography (TLC)
• Column Chromatography (CC)
PREPARATIVE THIN-LAYER CHROMATOGRAPHY
A method for rapid qualitative analysis, TLC here allows components of a mixture to be separated easily. The solid phase is made of a thin layer of silica mounted on a solid support, called the TLC plate. The properties of the silica and the properties of the components are used to draw the components up the plate. Differences in the properties of the components in the mixture means that each component will travel up the plate at different rate. This allows for the separation. The separated components can then be identified by comparing how far they travel up the plate relative to the reference standard.
PREPARATIVE COLUMN CHROMATOGRAPHY
The adsorption or partition chromatographic separations are carried out on a column of adsorbents packed in a glass or metallic tube in this technique. It can used for large volume of samples on scales from micrograms up to