There’s also other foreign matter in the tanks, especially new ones, distilling would still be a good idea
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Looking at that some more, it should be noted that the total weights of mystery oil they record relative to butane weight, are in the thousands of a percent if not millionths of a percent!
That means, that a 99.5% butane and a 99.999% butane… might even have the same amount of mystery oil.
And that the bulk impurities shown on these butane COAs, are NOT attributable to “mystery oil”.
So it seems to me that the purities listed on COAs are completely irrelevant to the whole mystery oil discussion. If there’s 0.5% of unknowns in your butane, but only .000001% non-distillable compounds (i.e. mystery oil), then 99.9999% of the impurities, aren’t being removed by distillation.
So, perhaps we must set aside this question of how clean your COA would have to be to justify non-distilling, because it’s irrelevant – as we see, the amount of non-distillable substances is far too low for any COA to reflect.
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I’m sorry but this whole thread is day 1 lab shit 
What is this thread even about ? Did everyone forget how to make a clean product or what ?
No solvent supplier can be trusted ever, there is always shmutz & mystery oil in their products every time.
Any extractor with half a brain knows this, if your not distilling your solvents your product sucks and you know it, period.
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Your end product is concentrated, just like the mystery oil was. No end product still has all of the butane left in it. That concentrated amount is what we’re not wanting in anyone’s end product.
As I’ve said before:
You can campaign all you want to not distill, that’s your thing. I’ll continue to have it done, and that’s my thing.
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The thread is about the fact myself and potentially others are distilling their solvent, have clean lab practises, got a clean coa with my gas and still popped for benzene. I’m going to be letting a nice quantity of butane reduce down with some mct oil mixed in on all further batches and submitting it for testing no matter what COAs show for solvents. That is my $.02 I got from this experience and felt it was with sharing. 
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I agree with this sentiment. Distilling your solvent is a generally recognized basic lab practice. If you choose not to do it, you better have validated controls to ensure that you don’t have an issue (re: what @MagisterChemist @TheGratefulPhil and @Cassin have been stumping). Anything short, you’re just a hack
I trust sigma and fisher a hell of a lot more than any king of the hill mfer and even with them it’s expected to treat the quality of process inputs with a healthy dose of scepticism
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Ok but Benzene boils at 80.1c so if your not boiling the shit out of your butane then the Benzene should stay in the collection
Wow, what slander on your part. Show me where I ever said not to distill it. I haven’t run butane in 3 years. If you think I am campaigning to poison people then show me one goddamn statement to that effect!
At atmosphere, no?
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I must have misinterpreted this as you saying that the contaminant is so little that it didn’t matter.
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The point i’m trying to make is that you can’t know if there’s mystery oil whether the COA says 99% or 99.9% or 99.9999999% – because the mystery oil makes up less than that anyway.
The only way you can know is actually trying it out.
It may be possible for a COA to read 99.999999%, and yet have gunk when you distill it.
It may also be possible for a COA to read 99.5%, and yet be squeaky clean in regards to non-distilling compounds.
Therefore, COAs are basically irrelevant and cannot tell you whether you need to distill regardless of what they say – that is my point.
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That’s what the literature states
80.1c @ 1atm
Stump the goog!
In all likelihood, butane and benzene have some azeotrope, and by boiling off all the butane you’re forcing the benzene to also boil off.
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I will admit to cranking the distillation runs pretty fast usually and my pump makes a vac when it gets low which could explain it distilling over.
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I distill n-butane at 33c
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Please excuse my rough recollection of the chemistry here…
From my understanding the dipole causes the higher bp and weights down the hydrocarbon with it
Is that not correct ?
You finish it at 33 or you distill the entire quantity at 33? I crank pretty much everything until the end.
Maybe we should be packing a filter spool on top of the vapour path when distilling tane to help reduce the chances of bringing benzene with the vapour ?
How do the gas suppliers remediate it ?
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I boil 99% of the volume and then drain the rest and discard it. Makes it easier to clean up too
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http://ddbonline.ddbst.com/AntoineCalculation/AntoineCalculationCGI.exe?component=Benzene
8c at 40mmhg if I’m reading this vapor pressure curve chart right