Isopropanol & ethanol separation

[thohry]

Hi all,
We are analyzing some residues in ethanol by GC with DB-FFAP column. It seems the IPA peak is under the ethanol. Anyone could help what kind of column I should use for this analysis.
Thanks for any inputs.

[CE Instruments]

Whilst not the column of choice it is possible to separate IPA and Ethanol on most columns provided the column is long enough , the capacity great enough (film thickness) and the temperature low enough.
More info. required

[rb6banjo]

You appear to be looking for an IPA impurity in an ocean of EtOH. I remember years ago trying to use IPA and an internal standard for determination of EtOH in beer and I struggled with the separation on a DB-Wax. You might switch to some thing like the Rtx-5 Alcohols column or the Rtx-BAC Plus 1:

http://www.restek.com/chromatogram/view ... %7C64-17-5

As CE said, the thickest film you can get would be advisable.

I made a sample where I put 1 drop of IPA (about 15 mg) in 4 mL of EtOH. I shot it on my GC-FID that has a Rtx-5 (30 m x 0.53 mm x 3.0 µm) and I was able to separate them with pretty good peak shapes. I was using about 20:1 split.

[thohry]

Thanks for your help. I may have to change to the Rtx column.

[chromatographer1]

I would suggest a 1301 or 1701 column for an excellent separation.

Any column with a boiling point mechanism of separation will work.

best wishes,

Rod

[rb6banjo]

That is an excellent idea Rod. I forgot about that phase. The 1701 is a very good column and I bet it would do the trick.

[cody841]

I use a 624 to separate, MeOH, EtOH, Acetone, ACN, and DMSO, IPA comes out between Acetone and ACN