I believe Wolfe is correct here and I think this is the root cause of or at least a major contributor to this issue.
I have also experienced this exact thing before with both benzene and acetone showing up in crazy amounts in cannabis lab tests.
I have also heard Dr. Mark Scialdone (@DrMark) who is a PhD organic chemist mention pretty much this exact same issue on Hashchurch.
Think about it, how does a GCMS work? I am no expert but what I do know is for the machine to analyze a gas, it must vaporize the sample first. Then it tests what compounds are in the vapor.
I believe that when you inject and vaporize a mixture of compounds that contain benzene rings at the temps used in GCMS (I’m not sure but I think it’s 300-500F, or 150-260C in most GCs) you will no doubt see benzene show up in random and varying amounts due to thermal degradation.
You would expect these test results to be somewhat inconsistent based on the different makeups of the various hash batches you send through the machine, just like you guys have been noticing.
Here are some quotes in support of what I’m saying:
I’m not trying to call you guys out, I’m just trying to illustrate the inconsistency of this issue and help us solve it.
Keep in mind, each batch of hash you make is distilling your solvent. If you distilled the solvent before you added it to your system and you STILL had some minor benzene present it would stay with the first batch of hash you make and you would not continue to see it in successive batches unless it was popping due to the thermal breakdown of the aromatic compounds in the hash itself during vaporization in preparation for GC testing.
The fact that you’re seeing a difference in benzene of 4x (2ppm vs. 8ppm) between different consistencies of hash also raises some flags that this might not be due to solvent contamination.