CHROMATOGRAPHY

In paper chromatography, there are two factors which the movement of each substance in the mixture need to depends on.

1. The solubility of the substance in the solvent. The substance moves with the solvent easily if the substance is very soluble in the solvent.
   
2. The adsorption of the substance on the filter paper. Some solids are able to attract other substance strongly and hold them on their surface. This is called ADSORPTION. The substance will not move with the solvent easily if the substance in the mixture is absorbed strongly by the filter paper.

Since none of the two substances have the same adsorption and solubility, each substance will travel a different distance along the filter paper. One substance is separated from another in this way.

The substances separated by chromatography do not have to be colored. Colorless substance can be made to show up by spraying the paper with a locating agent. Then reacts with each of the colorless substances in order to produce a colored product.

We often used chromatography to identify the substances in a mixture. It is commonly used in hospital. It help doctors to find out whether the patient has diabetes, if paper chromatography might fund out whether sugar is present in the patient's urine.

Chromatography can also used to identify different dyes used in food.

ADSORPTION

We called the solids which are able to attract other substances strongly and hold them on their surface ADSORBENTS.