Our propylene glycol (PG) is sourced from USA-based USP compliant manufacturers and is the exact source we use to dilute our PG nicotine products. Our PG is perfect for further diluting our nicotine base to your desired nicotine concentration. 120mL-1L aliquots ship in amber PET plastic bottles. As always, each lot of PG ships with its respective certificate of analysis, guaranteeing the USP status of this ingredient, and can be used to tag its individual lot number to such data. View an example of our past PG certificate of analysis here. Don't settle for an ingredient in your DIY arsenal that you are not comfortable using; choose a GC/MS validated chemistry! We recommend storing PG in a cool, dark, dry environment. PG is extremely hygroscopic, so make sure to store in a relatively dry environment with the cap SEALED TIGHTLY. If stored correctly, PG can have a shelf life exceeding two years.