In the traditional production process propylene glycol is made from propylene oxide reacted with water.
The resulting material is a mixture of mono-, di- and tri-propylene glycols that are then distilled to purify to the different grades of propylene glycol.
Propylene glycol is typically produced in two grades: technical or industrial grade, and USP/EP grade. The latter designates the requirements for the US Pharmacopiea and the European Pharmacopoiea, but this grade is also the grade foruse in food, feed and personal care applications.
The production of propylene glycol USP/EP is rigourously monitored and controlled through a track-and-trace system from the starting material throughout the production process up to the point of delivery. The high product quality standards, and compliance with stringent hygiene conditions, qualifies propylene glycol USP/EP (pharmaceutical grade) for use in health-sensitive applications.