My BHO/CO2 oil tested at a level over the state action limit. Is there anything I can do to clean it up?

The short answer is: no, not without completely changing the nature of the product.

Pesticides cannot be purged out or cooked away – once they are there they will tend to stay. There are a variety of techniques in chemistry that could be used to remove pesticide residue – large-scale chromatography, acid-base extractions, extractions and washes with various solvents, recrystallization – but to our knowledge none of these techniques have been used successfully to reduce the pesticide residue level from above the action limit to below the action limit in cannabis extract products intended for human consumption.

It is possible that vacuum distillation (“the clear”) may help to reduce pesticide residue in a finished oil – or it may concentrate it, depending on how volatile the contaminants are relative to cannabinoids. This would depend very much on volatility of the particular pesticide in question, and the efficiency of the distillation apparatus (number of theoretical plates). The effect of distilling cannabis oil to reduce pesticide residue levels has not been extensively tested, and should not be regarded as an effective means of removing pesticide residues. In fact, we have tested many distillation samples and found very high concentrations of pesticides, well over the limit.

It is also possible that active charcoal filtration can help reduce pesticide residue in finished oil, but like distillation may not work for all compounds and has not been extensively tested to ensure efficacy.

The safest bet is to only run material you know is clean – with a pesticide residue certificate of analysis – and to regularly clean all parts of your extraction system that could contaminate your product.