Distilled Spirits Analysis

[ScienceIsKing]

I've worked in a distilled spirits lab for a number of years. We use a 30m x .53mm x 1um UI Wax column for our trace analysis of congeners (diethyl ether, acetaldehyde, methanol, and n-propanol). We also analyze inprocess samples with high fusel oil content. I'm trying to get more accurate results for the inprocess samples (with high fusel oils) but it is difficult because the methanol peak is asymmetrical and butts up next to the ethanol peak, and because I'm calibrating over such a wide range of congeners (less than 1 ppm to over 2000 ppm). In looking at options to improve accuracy, I ran across some published methods from Phenomenex, and it seems they tend to recommend a 30m x .25mm x .25um Wax column. In fact, most of the half-dozen papers I looked at use a 0.25mm column diameter instead of a megabore.

Is a 0.25mm Wax column the standard size in the industry? Do most spirits analysis labs use a UI Wax column? When I contacted tech support, they steered me to a 0.32mm column instead of a 0.25mm column.

Is split mode with an internal standard the norm in the industry, for accurate results over a wide calibration range? Is this typically how labs handle such a wide calibration range for this type of analysis, or do labs split up the analysis into a lower and higher calibration range?

Also, I do not have access to a headspace GC.

Lastly, other than looking at Agilent and Phenomenex websites, what are some good web sites for published GC/HPLC/IC methods? I've tried just googling over the years but I'm not typically successful at finding what I'm looking for.

Thanks for any advice you might have.
-M

[rb6banjo]

I can't comment on "industry standards" but I've received methods for what others do and it's usually a wax. Dimensions vary.

Smaller bore columns are more efficient BUT the trouble with them is that you can overload them easily (adding too much sample to the column) and that can distort your chromatography. Split injection will help with that.

My big trouble with MeOH is that it coelutes (or elutes closely to) ethylacetate on Wax phases. My samples are lower in alcohol than yours so perhaps you have the EtOH problem because of large EtOH.

To get around my problem with coelution, I use a 1701 phase (30 m x 0.53 mm x 1.0 µm column, 5:1 split, only inject the needle full of sample as not to overfill the inlet liner and cause backflash, flame detector). This causes ethylacetate to elute after the ethanol AND MeOH elutes before. Sometimes I have to analyze spirits for MeOH and the 1701 works for me. Generally, I'm only looking for MeOH so i don't really care what happens after that in the chromatogram.