Chromatography Forum

I have set up this method D5501 for denatured ethanol in wt % and everything seems to be working fine as it should but one thing that drives me crazy is the denaturants calculation ?

How do you calculate denaturant vol % ? My cal standards are in wt % as client wants their purity of ethanol in wt% and methanol in wt % but need denaturants in vol % ? I don't even know how to calculate denaturants content whether it is vol % or wt %. Any help with this will be greatly appreciated.

Thanks,
Visa.

How do you calculate denaturant vol % ? My cal standards are in wt % as client wants their purity of ethanol in wt% and methanol in wt % but need denaturants in vol % ?

Can you add the hydrocarbon standard by volume? Or can you just use the density of the hydrocarbons in the standard to get their volume, and then those results would be in vol %.

We assayed hand sanitizers for ethanol content for cGMP, and for those (and for the beverage industry) results are always reported in vol %. Our 5890 GC with A.09 Chemstation would automatically deliver a sequence summary report with results in vol %.

Hello,

Thank you for your reply. We are testing the purity of denatured ethanol for our client. I did the curve in vol % as well just in case with the same standards. I do have Heptane in it and I use response factor of Heptane for all unknowns in the sample.

So, you calculate the denaturants from the GC itself ?
Denaturants calculation = 100 - ( ethanol content in vol % + water in vol% ) ???
Is that good ? problem is our client specification is so narrow min 1.95 - ,max 2.0 vol %. I'm not able to fit in that window.

Hello,

maybe the standard of customs laboratories of the European Union
ILIADe 453:2024 | CLEN Method
Determination of Isopropyl Alcohol and Methyl Ethyl Ketone
in Alcoholic Products by GC-FID Version 13 February 2024.
https://elab.bsu.by/download.php?id=371

With regards,
Sairhei Charapitsa

problem is our client specification is so narrow min 1.95 - max 2.0 vol %. I'm not able to fit in that window.

1.95 -2.0 is extremely tight, even pharmaceutical specifications are less stringent.

[/quote]
1.95 -2.0 is extremely tight, even pharmaceutical specifications are less stringent.
[/quote]
I know, I did mention that to our client and he says "we know what we are doing, thanks".

Since you include water too in the calculation, we are always around 1.9ish or 2.1ish. I just do not know what to do as most of the time, we are on the off-spec side.

Hello,

maybe the standard of customs laboratories of the European Union
ILIADe 453:2024 | CLEN Method
Determination of Isopropyl Alcohol and Methyl Ethyl Ketone
in Alcoholic Products by GC-FID Version 13 February 2024.
https://elab.bsu.by/download.php?id=371

With regards,
Sairhei Charapitsa

Thank you so much, I got the method set up per ASTM D5501 but denaturants specification is kind of crazy so having issue to be able to get everything in spec.

Just to give an update on this topic, we were able to determine denatured content by D5501 but the spec was so narrow, we were failing on it sometimes. Client ended up telling that it is a calculation from how much they add to pure ethanol. We just report as calculated value rather than by D5501. Thank you all for your help.

Aha !!! A communications issue !

Not that I EVER experienced that in my decades working....

Yes, sir.

Aha !!! A communications issue !

Not that I EVER experienced that in my decades working....

Just to give an update on this topic, we were able to determine denatured content by D5501 but the spec was so narrow, we were failing on it sometimes. Client ended up telling that it is a calculation from how much they add to pure ethanol. We just report as calculated value rather than by D5501. Thank you all for your help.

How does this approach ensure that the composition is what the client claims it to be?

How does this approach ensure that the composition is what the client claims it to be?

Client spec is very tight. we do run it by GC and get a very close result usually but sometimes we are off by 0.01-0.03 %. They said it is fine, just calculate the content and report it as calculated instead of D5501.

If you calculate the content on the basis of what the client says they did, then all you are doing is repeating the client's claim. This is not quality control.

Thanks, at least someone understands how I feel. I know, that was what our biggest concern too and we communicated the same. That's why they asked us to report as calculated rather than by D5501 until they change their spec. There is a disclaimer at the bottom as well to cover our butts.