MODEL RELEASED. Scientist examining a test tube containing a liquid obtained using the technique of column chromatography. The equipment for this is seen on the bench. Chromatography is used to separate out several components of a liquid mixture. It is especially useful for separating out components with similar physical properties. The column (at right) is filled with a porous gel. Different substances will travel down the column of gel at different rates. Two bands of a red/brown colour can be seen in the column. These are different components of a mixture that is being separated. The technique can be used to purify and isolate a required product.