Polysorbate 80 — E433, CAS 9005-65-6, HLB 15.0, oleic acid backbone — is the most widely specified synthetic emulsifier in food, cosmetics, and pharmaceuticals. At FoodEmul, it is our highest-volume product, shipped to manufacturers worldwide. This technical guide covers the full specification: chemistry, physical properties, regulatory status, safety data, and supplier qualification criteria.
CCCCCCCC/C=C\\CCCCCCCC(=O)OCC1C(C(C(O1)OCCO)OCCO)OCCO with ~20 EO units distributed across four arms
Chemical Structure
Polysorbate 80 is a non-ionic surfactant consisting of a sorbitan core (a cyclic ether derived from sorbitol dehydration) esterified with one oleic acid molecule and ethoxylated with approximately 20 moles of ethylene oxide distributed across the remaining three hydroxyl positions. The resulting molecule has:
Lipophilic tail: The C18:1 oleic acid chain (monounsaturated, with a cis double bond at C9) provides oil compatibility and contributes to the molecule’s liquid physical state at room temperature.
Hydrophilic head: Three polyoxyethylene chains (totaling ~20 EO units) extend into the aqueous phase, creating a thick steric barrier that prevents droplet coalescence in O/W emulsions. Each EO chain is terminated with a hydroxyl group capable of hydrogen bonding with water.
Architecture: The asymmetric distribution of EO units across the sorbitan ring creates a wedge-shaped molecular geometry that favors oil-in-water emulsion formation. This is in contrast to Span 80 (sorbitan monooleate, HLB 4.3), whose single hydroxyl head and single oleate tail produce a more cylindrical geometry favoring W/O emulsions.
Unlike small-molecule surfactants with a defined molecular weight, Polysorbate 80 is a polymeric surfactant — the ethoxylation step produces a distribution of oligomers with varying EO chain lengths. The molecular weight of 1,310.65 g/mol represents the nominal structure with exactly 20 EO units; commercial product has a distribution centered around this value. This polydispersity contributes to the product’s broad emulsification capability across a range of oil types.
What the Name Means
The “80” designates the fatty acid: oleic acid (C18:1, monounsaturated). This distinguishes it from other polysorbates:
Polysorbate
Fatty Acid
Chain
Physical Form @25°C
Polysorbate 20
Lauric acid
C12, saturated
Clear liquid
Polysorbate 40
Palmitic acid
C16, saturated
Viscous liquid
Polysorbate 60
Stearic acid
C18, saturated
Waxy semi-solid
Polysorbate 80
Oleic acid
C18:1, unsaturated
Viscous liquid
Physical Properties
Property
Value
Test Method
Appearance
Clear to slightly hazy, amber to golden-yellow viscous liquid
Visual
Odor
Characteristic, mild fatty odor
Olfactory
HLB Value
15.0 (highly water-soluble, O/W emulsifier)
Griffin method
Viscosity (25°C)
300–500 mPa·s
Brookfield
Density (25°C)
1.06–1.10 g/cm³
USP <841>
Melting Point
< –20°C (does not crystallize; remains liquid)
DSC
Pour Point
Approximately –20°C (pumpable in cold storage)
ASTM D97
Boiling Point
> 100°C at atmospheric pressure; thermal decomposition begins above 250°C
TGA
Flash Point
> 150°C (Cleveland open cup)
ASTM D92
Refractive Index (25°C)
1.470–1.474
USP <831>
Surface Tension (0.1% aq., 25°C)
~42 mN/m
Du Noüy ring
Critical Micelle Concentration (CMC)
~0.012 mM (1.6 × 10⁻² g/L)
Surface tension isotherm
Solubility Profile
Solvent
Solubility
Notes
Water
Fully soluble
Forms clear to slightly hazy solutions; solubility decreases above 70°C (cloud point effect)
Ethanol
Soluble
Fully miscible at all concentrations
Isopropanol
Soluble
—
Ethyl acetate
Soluble
—
Propylene glycol
Soluble
Common co-solvent in cosmetic formulations
Vegetable oils
Dispersible to soluble
Solubility increases with temperature; fully dispersible above 60°C
Mineral oil
Dispersible
Limited solubility; use Span 80 as co-emulsifier for mineral oil systems
Chemical Specifications by Grade
Parameter
Food Grade (FCC/USP)
Pharma Grade (USP/Ph. Eur.)
Industrial Grade
Acid Value (mg KOH/g)
≤ 2.0
≤ 2.0
≤ 7.5
Saponification Value (mg KOH/g)
45–55
45–55
45–60
Hydroxyl Value (mg KOH/g)
65–80
65–80
60–85
Oxyethylene Content (%)
65.0–69.5
65.0–69.5
65.0–70.0
Water Content (%, Karl Fischer)
≤ 0.5
≤ 0.3
≤ 1.0
Peroxide Value (meq/kg)
≤ 5
≤ 2
≤ 10
Heavy Metals (as Pb, ppm)
≤ 10
≤ 10
Not specified
Arsenic (ppm)
≤ 1
≤ 1
Not specified
1,4-Dioxane (ppm)
≤ 10
≤ 10
Not specified
Ethylene Oxide (ppm)
≤ 1
≤ 1
Not specified
Pharma-grade note: For parenteral and ophthalmic applications, verify peroxide value and impurity profile against the relevant pharmacopeia monograph (USP-NF / Ph. Eur. / JP). Oxidative degradation of the oleic acid chain can introduce reactive species that compromise API stability. The tighter peroxide limit (≤ 2 meq/kg vs. ≤ 5 for food grade) reflects this heightened sensitivity.
Stability and Storage
Condition
Behavior
pH Stability
Stable across pH 4–10; optimal performance at pH 5–7. At pH < 3 or > 11, ester bond hydrolysis accelerates significantly
Thermal Stability
Stable up to 100°C for short durations; avoid prolonged heating above 150°C. Autoclaving (121°C, 15 min) is acceptable for pharma-grade material
Oxidative Stability
Oleic acid chain susceptible to oxidation at the C9 double bond — store under nitrogen headspace for bulk tanks. Addition of 0.01–0.05% BHT or tocopherol extends oxidative stability
Microbial Stability
Resistant to microbial growth when stored sealed and dry; water activity below 0.6
Storage Recommendation
Cool (15–30°C), dry, ventilated area; keep containers tightly closed; protect from direct light and UV exposure
Shelf Life
24 months from date of manufacture in original sealed container. Retest acid value and peroxide value after 18 months
Cold Storage Behavior
Remains liquid and pumpable at temperatures as low as –20°C. Unlike Polysorbate 60 (which solidifies below 25°C), Polysorbate 80 requires no pre-heating before use in cold-process or refrigerated manufacturing environments
Contact FoodEmul.com for Certificate of Analysis (COA), Technical Data Sheet (TDS), Safety Data Sheet (SDS), or to request a sample.
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