Pharmaceutical and food-grade propylene glycol meeting USP-NF and FCC specifications for the U.S. market. FDA GRAS, ICH Q3C Class 3 solvent. Suitable for oral, topical, parenteral, and inhalation pharmaceutical formulations; food processing; cosmetics; and vaping liquids. COA, SDS, and full traceability with every order.
USP Grade — safe for human contact and ingestion: Propylene glycol USP grade meets pharmaceutical and food-grade specifications and is approved for use in products that contact or are consumed by humans. This page covers USP grade only. For industrial applications (resins, antifreeze, heat transfer), see our Industrial Grade PG page — industrial grade is NOT suitable for food, pharmaceutical, or personal care use.
Meets current USP-NF and FCC monograph specifications. Lot-specific COA provided with every order.
| Assay (GC) | ≥99.5% |
|---|---|
| Water | ≤0.2% |
| Heavy metals | ≤5 ppm |
| Color (APHA) | ≤10 |
| Chloride | ≤35 ppm |
| Sulfate | ≤60 ppm |
| Oxidizing substances | Passes USP test |
| Reducing substances | Passes USP test |
| Residue on ignition | ≤0.007% |
| Chemical Name | Propylene Glycol (1,2-Propanediol) |
|---|---|
| Grade | USP-NF / FCC / FDA GRAS |
| CAS Number | 57-55-6 |
| Molecular Formula | C₃H₈O₂ |
| Molecular Weight | 76.09 g/mol |
| EINECS Number | 200-338-0 |
| EU Food Additive Number | E1520 |
| TSCA Status | Listed on TSCA inventory |
| Transport Class | Not regulated (flash point >60°C) |
| Appearance | Colorless, clear, viscous liquid |
|---|---|
| Odor | Nearly odorless |
| Boiling Point | 187–188°C (369–370°F) |
| Melting Point | -59°C (-74°F) |
| Flash Point | 99°C (210°F, closed cup) |
| Density @ 20°C | 1.036 g/mL (8.65 lb/gal) |
| Viscosity @ 20°C | ~56 mPa·s |
| Refractive Index (n20/D) | 1.4324–1.4329 |
| Vapor Pressure @ 20°C | ~0.13 hPa |
| Water Miscibility | Fully miscible |
PG USP serves as a safe, versatile excipient and carrier across pharmaceutical, food, cosmetics, and consumer product formulations where human contact or ingestion is involved.
Propylene glycol USP is a multi-route pharmaceutical excipient listed in the FDA Inactive Ingredient Database for use in oral solutions, tablets, capsules, topical creams, ointments, gels, parenteral injections, and inhaled formulations. As a solvent and co-solvent, PG improves solubility of poorly water-soluble active pharmaceutical ingredients (APIs), enabling stable liquid and semi-solid dosage forms. It also functions as a humectant (preventing drying of topical formulations), a preservative potentiator (enhancing antimicrobial activity of parabens and other preservatives), and a skin-penetration enhancer in transdermal systems. PG is classified ICH Q3C Class 3 — the lowest concern category — with no established acceptable daily intake limit below 50 mg/kg/day, permitting its use in pharma synthesis and formulation under normal GMP controls.
Propylene glycol is FDA GRAS (21 CFR 184.1666) and approved for direct addition to food as a humectant, solvent, emulsifier, and preservative. In food applications, PG maintains moisture in baked goods, retains texture in packaged snacks, serves as a carrier for food flavors and colors, and acts as an antifreeze component in refrigerated food systems. It is listed in the EU as food additive E1520. PG is used in USDA-regulated meat and poultry products, GRAS for pet food applications, and listed in the FCC (Food Chemicals Codex) with confirmed purity standards.
Propylene glycol is among the most widely used ingredients in cosmetic formulations — listed in INCI (International Nomenclature of Cosmetic Ingredients) as "Propylene Glycol." In cosmetics, PG functions as a humectant (drawing moisture to the skin), solvent (dissolving fragrance compounds, UV filters, and preservatives), penetration enhancer (improving delivery of active ingredients through the skin), and antimicrobial potentiator. It is a standard ingredient in moisturizers, serums, toners, hair conditioners, shaving products, antiperspirants, and sunscreens. PG is approved in the EU Cosmetics Regulation and globally accepted in personal care formulations.
Propylene glycol is one of the two primary base ingredients in e-cigarette and vaping liquids (e-liquid), alongside vegetable glycerin (VG). USP grade is required for vaping applications due to the inhalation route of exposure. PG contributes lower viscosity (allowing effective wicking in coil systems), efficient flavor-compound carrying, and a characteristic "throat hit" that mimics the sensation of combustible tobacco. PG/VG ratios in e-liquids typically range from 50/50 to 70/30 (PG:VG). All vaping applications require pharmaceutical-grade PG — industrial grade is not acceptable for inhaled use.
USP grade vs. industrial grade: Propylene glycol USP grade is tested to additional pharmaceutical standards — including heavy metals (<5 ppm), oxidizing substances, and reducing substances — that industrial grade does not require. For any application involving human ingestion, topical contact, or inhalation, USP grade is required. Industrial grade PG is suitable only for technical uses such as antifreeze, heat transfer, resin synthesis, and hydraulic fluids.
From R&D samples to bulk quantities. Contact us for pricing, MOQ, and lead times.
All documentation available on request via the quote form below.
USP-grade propylene glycol (CAS 57-55-6) meets the specifications of the United States Pharmacopeia (USP-NF) and is FDA GRAS for food use. It is a colorless, nearly odorless, viscous liquid with assay ≥99.5%, and is classified ICH Q3C Class 3 (low toxicity concern). USP grade is required for pharmaceutical, food, cosmetic, and vaping applications involving human contact or ingestion.
Industrial PG meets general chemical purity specifications but is not tested for pharmaceutical or food-contact safety parameters (heavy metals, oxidizing/reducing substances, chloride limits). USP grade undergoes additional testing to current pharmacopeia monograph requirements. Only USP grade is approved for pharmaceutical, food, cosmetics, or vaping use — industrial grade must not be used where human ingestion or inhalation occurs.
Yes. Propylene glycol USP is FDA GRAS (21 CFR 184.1666) for direct food use as a humectant, solvent, emulsifier, and preservative. It is also EU E1520 and FCC listed. PG is used in baked goods, packaged snacks, food flavorings, colorings carriers, and pet food at permitted levels established by FDA and Codex Alimentarius.
Yes. For e-cigarette and vaping liquids that are inhaled, USP-grade (or equivalent pharmaceutical grade) propylene glycol is required. The inhalation route demands the higher purity and absence of heavy metals and other impurities that industrial grade may contain. All responsible vaping liquid manufacturers use pharmaceutical-grade PG and VG.
ICH Q3C (Guidelines for Residual Solvents) classifies pharmaceutical solvents by toxicity. Class 3 solvents have low toxic potential — no established ADI limit below 50 mg/kg/day. Propylene glycol is Class 3, meaning it can be used in drug synthesis and formulation without strict per-dose limits when GMP controls are applied. This classification makes PG one of the safest pharmaceutical solvent options available.
CARMELSOLV™ supplies PG USP grade in sample/R&D quantities, 5-gallon pails, 55-gallon drums (steel or poly), 275–330 gallon IBC totes, and bulk tanker quantities. Contact us for pricing, lead times, and documentation requirements for your application.
Yes. CAS 57-55-6 is listed on the U.S. EPA TSCA inventory. USP and industrial grades share the same CAS number — the grade designation reflects purity and testing specifications, not a different chemical substance.
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