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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: goanna_s on November 23, 2005, 01:05:55 AM

Title: Elution order of ethanol and water in GC
Post by: goanna_s on November 23, 2005, 01:05:55 AM
Can someone tell me why, when analysing a mixture of water and ethanol, the water peak comes out first?

I thought that less polar, more volatile compunds would elute first....


Anna
Title: Re:Elution order of ethanol and water in GC
Post by: Vitnir on November 23, 2005, 09:50:12 AM
If its a standard non-polar column then water doesnt interact with the solid phase very well, ethanol can interact and is chromatographed slower. If you had a MS-detector you would see traces of water during the entire run and ruins some of the resolution, a polar column would be a better choice.