column selection help

[Regency TAFE]

I run some teaching labs at a college and I'm looking at purchasing a CP-Wax 57 CB column for ethanol analysis practical. I need to know what ID and film size to get, we need reasonable speed but more importantly high resolution as we want to be able to test our own beers with good accuracy. at the moment there is some tailing using our DB-Wax column and results for beer are usually off by around 0.2-0.3%

[walter]

A wax column is probably as good a choice as any. I would sample the vapor, ie, headspace rather than inject beer directly on the column. Would probably not hold up very well for the long haul.

[Consumer Products Guy]

We've used Supelco Nukol for ethanol assay in hand sanitizer products for years. We're actually using the same column as when we started the assay in the 1990s.

Since you'll be diluting your samples a lot, don't think that the beer matrix will affect the column that quickly. We use a 0.53mm i.d. column at about 40C with split injection, and use n-propyl alcohol as internal standard. We have no issues meeting all system suitability tests. Since we inject from water as solvent, we keep the injection size small at 0.5 µl.

[AICMM]

Regency TAFE,

Have you thought about height?

Best regards,

AICMM

[Andy F]

I run some teaching labs at a college and I'm looking at purchasing a CP-Wax 57 CB column for ethanol analysis practical. I need to know what ID and film size to get, we need reasonable speed but more importantly high resolution as we want to be able to test our own beers with good accuracy. at the moment there is some tailing using our DB-Wax column and results for beer are usually off by around 0.2-0.3%

We use 0.53 mm HP Wax column (15 m) with n-propanol 4% as ISTD for our beer analyses, ratio 1:1 sample:ISTD, with no column issues. You will need to change the liner fairly reguarly though.

[aldehyde]

I agree, you should use headspace to do this analysis if possible. Direct injection if you have to, but keep injection volume low and change liner frequently.