Propylene glycol
Propylene glycol suppliers and sourcing guide
Propylene glycol is a small synthetic diol, a clear, nearly odorless liquid that mixes with water, alcohol and many oils. It is made mainly by hydrating propylene oxide, with a growing share made from glycerin by hydrogenolysis. Cosmetic and personal care brands buy USP/EP grade propylene glycol in drums or totes as a solvent and humectant for creams, deodorants, hair products and extracts.
- Also known as
- 1,2-Propanediol · Propane-1,2-diol · PG · E1520 · CAS 57-55-6
- Facts checked
- November 2026
Forms and grades of propylene glycol
Suppliers sell different products under the same name. Specify the one you need.
USP / EP grade
High-purity propylene glycol (99.5% or higher) meeting pharmacopeial monographs; the usual grade for cosmetics, food and oral products.
Bio-based
Propylene glycol made from glycerin rather than petroleum-derived propylene oxide, sold with a bio-based carbon content figure.
Industrial grade
Grade for antifreeze, de-icing and resins; not for cosmetics or food.
Kosher and halal
USP grades are widely offered with kosher and halal certificates, which matter for oral-care and ingestible uses.
What to check on the COA
Compare each result with your own specification when the lot arrives.
- Identity
- IR spectrum and specific gravity matched to the monograph.
- Assay
- Propylene glycol content by GC, usually 99.5% or higher.
- Diethylene glycol and ethylene glycol
- GC limit test for DEG and EG, required by USP and a known contamination risk for glycols.
- Water
- Karl Fischer titration.
- Acidity, color and residue on ignition
- Titratable acidity, APHA color and residue on ignition, which reflect oxidation and handling.
- Heavy metals
- Lead, arsenic and other elements by ICP-MS or ICP-OES against the supplier's specification or the applicable USP, FCC or cosmetic-grade limit.
Storage, lots and expiry
Storage and shelf life
Keep propylene glycol in closed stainless steel, HDPE or lined drums at room temperature, protected from moisture and from long heat exposure, which can form acidic oxidation products. Nitrogen blanketing is used for bulk tanks. Shelf life is set by the supplier, often two years or more, with a retest of assay, water and acidity to extend it.
Lots and expiry dates
Record assay, water and DEG/EG result for each lot, along with whether it is petroleum-based or bio-based, since that can change label and sustainability claims. Rotate FIFO.
Regulatory status
Facts from regulators and standards bodies, each linked to its source.
21 CFR 184.1666 identifies propylene glycol as 1,2-propanediol and lists its food uses, including as a humectant and as a solvent and vehicle.
Source: ecfr.gov (opens in a new tab)Health Canada's Natural Health Products Ingredients Database lists propylene glycol (CAS 57-55-6) as an approved ingredient with non-medicinal purposes including humectant and solvent.
Source: webprod.hc-sc.gc.ca (opens in a new tab)The same database entry sets intake limits by age for propylene glycol, up to 500 mg/kg bw/day for those 5 years and older, citing EMA (2017).
Source: webprod.hc-sc.gc.ca (opens in a new tab)
This is general information, not regulatory advice. Status differs by country and by how the ingredient is used, so check the rules for your product and market.
Propylene glycol suppliers
Manufacturers and distributors whose own websites say they sell it.
We are checking propylene glycol suppliers now
Every listing is checked against the supplier’s own website before it goes live, so this list fills in over the coming weeks. The specs and COA checklist above are ready today.
Sell propylene glycol? Request a listingFrequently asked questions
What forms of propylene glycol can brands buy?
Common forms include uSP / EP grade, bio-based, industrial grade and kosher and halal. Ask each supplier for the specification sheet of the exact grade they quote.
What should the COA for propylene glycol include?
Expect identity, assay, diethylene glycol and ethylene glycol, water, acidity, color and residue on ignition and heavy metals, each with its method, specification and result for that lot.
How should propylene glycol be stored?
Keep propylene glycol in closed stainless steel, HDPE or lined drums at room temperature, protected from moisture and from long heat exposure, which can form acidic oxidation products. Nitrogen blanketing is used for bulk tanks. Shelf life is set by the supplier, often two years or more, with a retest of assay, water and acidity to extend it.
What is the regulatory status of propylene glycol?
21 CFR 184.1666 identifies propylene glycol as 1,2-propanediol and lists its food uses, including as a humectant and as a solvent and vehicle. Health Canada's Natural Health Products Ingredients Database lists propylene glycol (CAS 57-55-6) as an approved ingredient with non-medicinal purposes including humectant and solvent. The same database entry sets intake limits by age for propylene glycol, up to 500 mg/kg bw/day for those 5 years and older, citing EMA (2017).
More cosmetic bases, emollients and surfactants
- GlycerinGlycerol · Glycerine
- Butylene glycol1,3-Butanediol · 1,3-Butylene glycol
- Propanediol1,3-Propanediol · Trimethylene glycol
- Pentylene glycol1,2-Pentanediol · Pentane-1,2-diol
- Cetearyl alcoholCetostearyl alcohol · Alcohols, C16-18
- Cetyl alcohol1-Hexadecanol · Palmityl alcohol
- Stearyl alcohol1-Octadecanol · Octadecyl alcohol
- Behenyl alcoholDocosanol · 1-Docosanol
- Caprylic/capric triglycerideMedium-chain triglycerides · MCT
- Isopropyl myristateIPM · Tetradecanoic acid, 1-methylethyl ester
- Isopropyl palmitateIPP · 1-Methylethyl hexadecanoate
- Coco-caprylateCoco-caprylate/caprate (related grade) · Coconut alcohol caprylate
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