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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: Dolphinsiu on July 01, 2008, 03:49:21 AM

Title: GC
Post by: Dolphinsiu on July 01, 2008, 03:49:21 AM

What is the working principle of GC?

I only know GC is a qualititative method to fractionate the gaseous mixture into simplier compounds, depending their retention time in separating column. GC can be catagorized into gas-gas chromatography and gas-liquid chromatography. Their retention time depends on the polarity of stationary phase and mobile phase.The more polar the stationary phase is used, the more soluble in stationary phase is the polar mobile phase, the longer is the retention time of that mobile phase.

Do anyone has some supplementary information or opinion in the above wording?

Title: Re: GC
Post by: Borek on July 01, 2008, 04:05:50 AM

Substances are adsorbed/deadsorbed on the stationary phase. This equilibrium is responsible for slowing down the substance progress in the column (adsorbed substance doesn't move with mobile phase). As equilibrium is unique for each stationary phase/substance pair, different substances are slowed different, which makes them separate.