Polysorbate 20 — Frequently Asked Questions

Polysorbate 20 is mainly a solubiliser. It disperses small amounts of fragrance, essential oils and botanical extracts into clear water-based products such as toners, body mists, micellar waters and room sprays. It is also a mild co-surfactant in baby shampoos and facial cleansers. The usual ratio of polysorbate 20 to oil ranges from about 2:1 to 5:1, depending on the oil.

As a starting point, use about two to five parts polysorbate 20 for each part of fragrance or essential oil, mixing the two together before adding water. Some oils, especially those rich in heavier components, need more. Add water slowly and check clarity. Adjust the ratio in small trials, because the right amount depends on the oil composition.

In immunoassays and similar tests, low concentrations of polysorbate 20, often around 0.05%, reduce non-specific binding of proteins to plastic surfaces and help wash away unbound material. It is mild enough not to denature most antibodies. Laboratory work normally needs a high-purity grade with low peroxide and impurity levels, so specify the grade clearly.

Generally, yes. Polysorbate 20 is based on saturated lauric acid, which has no double bond to oxidise, while polysorbate 80's oleic acid chain can oxidise more readily. Both can still form peroxides through their polyoxyethylene chains during long storage in air and light, so keep containers sealed, cool and protected from light.

Acid value, saponification value and hydroxyl value together confirm that the product is a polysorbate with the expected ester and ethoxylation level. Fatty-acid composition, with lauric acid as the main component, distinguishes polysorbate 20 from polysorbate 60 or 80. Water, peroxide value and residue on ignition then indicate quality and storage. Check these on each certificate of analysis.