method development

[mmegliol]

Hi,

I’m trying to develop a method to separate fusel oil on alcoholic beverage, the main component are:
Acetaldehyde
Methanol
Methyl acetate
n-propanol
2 butanol
Ethyl acetate
Iso-butanol
n-butanol
isoamyl alchol
Active amyl alchol
Sec-butyl acetate
n-amyl alchol

usually this type of analysis is done with a packed column, I would like to do it with a capillary column to don’t change my GC (I’m using it for other method that required capillary!)

I tryed with different column CARBOWAX, the last was Supelcowax 10 60m, 0.32 but no matter what I change I always had problem at the end if the chromatogram ( no resolution at all on the amyl alcohol).

I found online an application that was perfect for me, from Supelco #164, with SPB-20, the only difference is that they run with nitrogen and I use helium, on the application is written that only the analysis time will change but is not really like that, all the chromatogram change and I completely lost resolution between acetaldehyde, methanol end ethanol, the rest of the chromatogram is not bad.

any suggestion as a set up in a method translation like that? ( I try different temp, flow but no much improvement ).
Is there any other column more appropriate to do this type oof analysis?
[/list]

[oscarBAL]

Hello mmegliol; I use to run this method for Rum a couple of year before in a CARBOWAX capillary column of 25 mts; the resolution was good but the problem was in the separation of Acetaldehyde - Methanol. I dont remember very well the chromatographic contidition but the Method start at 20C and 12 psi (hard to reach that temperature, and sometime I deceided to cheange to 24 C and 10 psi more reliable) and then continue with a slow ramp.

what are the chormatographic condition u found in the internet?

[mmegliol]

it's funny becasue on a carbowax 60m I have no problem to separate acetald and metoh, but on the SPB-20 is a disaster!

on the run with nitrogen they used 40 hold 4 min, ramp4 by min until 110 hold.
velocity at 11 cm/sec.

thanks for your help.