Essay about A Experiment On Gas Chromatography

2119 Words Nov 2nd, 2016 9 Pages
Part A
Gas Chromatography
What is it?
Gas chromatography is a variation of chromatography used in analytical chemistry for separating and analysing components that can be vaporised without decomposition ("Gas Chromatography", 2016). This technique involves using a gas as the mobile phase. There are two types of gas chromatography:
• Gas-solid chromatography – separates substances on the basis of their different strengths of adsorption on the solid
• Gas-liquid chromatography – separates substances in the basis of different solubilities in the stationary phase
How does it work?
In a gas chromatograph the sample being analysed is inserted with a syringe into a heated flowing gas, usually helium or argon. The sample is immediately vaporised and carried through the column by the gas.
In gas-solid chromatography the mixture being analysed is separated by differential adsorption onto the solid which acts as the stationary phase. The solid used is finely divided thereby maximising its surface area. This solid is packed into a long thin tube or column, typically 0.5-2m long with a diameter of 3-9mm, which is wound into a spiral so it can fit into a reasonably small oven.
In gas-liquid chromatography the components of the mixture dissolved in an adsorbed liquid, which acts as the stationary phase, then vaporises back into the gas. The more soluble a compound is in the stationary phase, the more slowly it moves through the column thereby effecting the separation.
In recent decades…

Related Documents