Best Question of the Week (Live_Resin_Peasant):
If the Co2 is introduced prior to the butane and there is clearly Co2 in it still, how is there Co2 and not Butane in it as well?
The Co2 is tied to the butane and probably, although not confirmed, a microscopic bit of water. It can not be removed by vacuum oven. In fact, quite the opposite would occur. The vacuum oven would reduce beneficial volatiles and reduce weight, only increasing residual solvent levels by volume.
However, a carbon with two oxygens and four carbons with six hydrogens are two different molecules in that the butane remaining above is between 500-5000ppm (just like every other liquid hydrocarbon extract) but the Co2 molecule transitions from solution to gas phase far differently than butane transitions between solution and gas phase.
This example is a bit active and we carry residual and Co2 levels down to acceptable and state-compliant levels. But the Co2 still remains when butane finally does not and even in small amounts, it’s activity is still identifiable.