tell me about principle of column chromatography?

Answer 1

Column chromatography in chemistry is the preparative application of chromatography. It is used to obtain pure chemical compounds from a mixture of compounds on a scale from micrograms up to kilograms using large industrial columns.


Column chromatography on a large scale in the 1950s, the chemist uses a ladder to refill eluent, he operates not one but 11 columns, barely visible are erlemeyer receptibles on the floorThe classical preparative chromatography column is a glass tube with a diameter from 5 to 50 mm and a height of 50 cm to 1 m with a tap at the bottom. A slurry is prepared of the eluent with the stationary phase powder and then carefully poured into the column. Care must be taken to avoid air bubbles. A solution of the organic material is pipetted on top of the stationary phase. This layer is usually topped with a small layer of sand or with cotton or glass wool to protect the shape of the organic layer from the velocity of newly added eluent. Eluent is slowly passed through the column to advance the organic material. Often a spherical eluent reservoir or an eluent-filled and stoppered separating funnel is put on top of the column.

The individual components are retained by the stationary phase differently and separate from each other while they are running at different speeds through the column with the eluent. At the end of the column they elute one at a time. During the entire chromatography process the eluent is collected in a series of fractions. The composition of the eluent flow can be monitored and each fraction is analyzed for dissolved compounds, e.g. by analytical chromatography, UV absorption, or fluorescence. Colored compounds (or fluorescent compounds with the aid of an UV lamp) can be seen through the glass wall as moving bands.

http://en.wikipedia.org/wiki/Column_chromatography

Answer 2

Column chromatography applies the principle of selective adsorption between two phases, the mobile and the stationary phases. It is a separation process wherein the substances which have affinity for the stationary phase stay behind in the medium while substances which have affinity for the diluent or mobile phase move with the diluent towards the end of the medium. After the separation process, methods of determining the concentration of the substances separated, differ depending upon the properties of the analyte being determined.

Answer 3

Gas chromatography (GC for short) uses either a solid phase or a liquid immobilized on the surface of a solid as the separation medium and a gas such as helium, nitrogen or hydrogen as the mobile phase. In the oldest GC systems the column was a tube filled with silica gel and the separation medium was a highly viscous silicon oil that as mixed with the silica gel. Because of the relatively high carrier gas flow rates needed for large beds the sample size needed was also relatively large. Packed columns eventually gave way to capillary tube GC. The capillary GC column is an open tube of fused quartz from 5 to 30 micrometers in diameter. The separation is again a viscous silicon oil that is deposited on the wall of the tube. Because both the tube and the gas flow rates are very small the sample volume can also be very small. Detection of the sample in the effluent gas can be achieved by thermal conduction, flame ionization or mass spectrometer (there are other techniques, these are the most common). Capillary GC offers the advantage of high resolution and the ability to analyze extremely small samples, nanogram to microgram range.

Answer 4

It is based on the principle of selective adsorption of different adsorbates by an adsorbent

Answer 5

i dont know i am just writting it to get points