Gas Chromatography

[TheBoneDoctah]

I am a little confused as to what exactly accounts for the difference in retention times in a gas chromatographer. Watching Chad's videos, he says that the difference in retention times is because of the vaporization temps. The compounds with the highest vaporization temps will elude last because they aren't in the gas phase as long.

However, on a practice exam I took, they say that the major factor hindering the flow of the vapor during gas chromatography is the attractive force between the compound and the packing material in the column. The greater the affinity for the packing, the more slowly the compound migrates through the column.

Anyone know the correct answer?

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[chenzt]

I am a little confused as to what exactly accounts for the difference in retention times in a gas chromatographer. Watching Chad's videos, he says that the difference in retention times is because of the vaporization temps. The compounds with the highest vaporization temps will elude last because they aren't in the gas phase as long.

However, on a practice exam I took, they say that the major factor hindering the flow of the vapor during gas chromatography is the attractive force between the compound and the packing material in the column. The greater the affinity for the packing, the more slowly the compound migrates through the column.

Anyone know the correct answer?

Sample is quickly vaporized before it even reaches the beginning of a column. Second answer is correct.

 

[AKMCAT]

I am a little confused as to what exactly accounts for the difference in retention times in a gas chromatographer. Watching Chad's videos, he says that the difference in retention times is because of the vaporization temps. The compounds with the highest vaporization temps will elude last because they aren't in the gas phase as long.

However, on a practice exam I took, they say that the major factor hindering the flow of the vapor during gas chromatography is the attractive force between the compound and the packing material in the column. The greater the affinity for the packing, the more slowly the compound migrates through the column.

Anyone know the correct answer?

It depends on the attraction to the column of the chromatography ( usually will be silica gel). compounds are injected in their gas phase; although it is true that the compound with the highest vaporization temperatures will elude last, the idea of chromatography still depends only on the the attraction to either stationary phase or the gas phase. So given any question you would focus on these concepts. Distillation however is solely based on vaporization. Hope this makes sense.