Well mark me down as dubious but not invested enough to research it. However, I do wonder if you/they test or filter for poisonous impurities like methanol? Seems like a bit of a risk?
Testing and filtering is accomplished by the distillation itself. A very basic understanding of what comes out when is more than enough for a simple pot still and only one or two passes. Humans have been doing that since long before the concept of a molecule even existed.
If you decide to mess around with a large fractionating column though, do read up and make sure you have a full conceptual understanding of how the chemistry works. Even seemingly benign chemicals can be extremely dangerous to ingest or handle once concentrated. (For example, vinegar. Dilute acetic acid makes for a good salad dressing. Above 90%, contact will leave you with severe burns and scarring.)
