What's in YOUR solvent tank (today)?

So rather than derail yet another thread with the latest value I can turn on my CLS, I figured I’d start yet another thread

@pdxcanna That is from my working solvent.

Refills are 30:70 propane:butane. Not supposed to be any iso in there.

We tried tracking blend with pressure, and the superheat in the non-ideal gas above our liquid solvent, or atmosphere that we’re accumulating from somewhere (more likely) made that unreliable.

We are just refilling with 30:70 and seeing where we land. So I had to figure out where we landed…

The injections shown are both 1:10,000 dilutions with atmosphere.

In addition to the isobutane I’ve got at least three other peaks I need IDs on when I inject a 1:10 dilution

hmm, is a 1:10 dilution of flammable solvent into a stream of H2 a good idea?

What’s the UEL again? The LEL?

How do I know its iso butane?

I’m making an educated guess after injecting a standard :wink:


I found this.

Following the logic wouldn’t propene elute to the left of (prior to) propane?


This is the source. Couldn’t get a clean hyperlink.



That might be a different column though but it follows the same logic I presented.

See peaks 5,6

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Yep, that IS a different column, and method.

I’ve got a benzene, but would rather not start spreading ppb around the lab.

That peak is the largest mystery peak, but there are atleast a couple of others that show up in the higher loadings.

Starting with the COA for the input gas was going to be my first approach.

@srihugh1 might also have C1-C18 hydrocarbon data on the Hayes D column I’m using.


It sure looks like you’re on to something.

Is your hypothesis that butane or propane is being isomerized to iso, or that the origin fill tank gas is contaminated with iso?

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I would lean towards this.

But I’m a laymen, so not saying much



Me too, but sometimes I learn something asking🤷‍♂️


How about, unexpected.

“Contaminated” is perhaps a stretch for that and neo-pentane.

(Test your beer for methanol…)

So long as they don’t contain benzene…


Propylene would make sense as a contaminant of the feedstock.

Does method really change elution order with gc? It’s not like you have a binary or ternary mobile phase, it’s just mobile versus stationary phase interactions and the ramp of the oven. I thought it all boils down to (pun intended) volatility.


Column used can change order. Temp/pressure profile shouldn’t. Different carrier gas (He/H2) might


This is very cool, well done thus far. Any updates?

Did you try different carrier gas?

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