for molecular biology, viscous liquid

Polyethylene glycol sorbitan monolaurate, Polyoxyethylenesorbitan monolaurate
CAS Number:
MDL number:

Quality Level


for molecular biology




≥40.0% (GC)


viscous liquid

mol wt



lauric acid, ≥40% (balance primarily myristic, palmitic, and stearic acids)

refractive index

n20/D 1.468 (lit.)


60 mg/L


1.095 g/mL at 25 °C (lit.)


suitable for molecular biology

foreign activity

Endonuclease-exonuclease and RNase, none detected



InChI key


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General description

Tween®20 is a polyoxyethylene sorbitol ester that belongs to the polysorbate family. It is a nonionic detergent having a molecular weight of 1,225 daltons, assuming 20 ethylene oxide units, 1 sorbitol, and 1 lauric acid as the primary fatty acid. The ethylene oxide subunits are responsible for the hydrophilic nature of the surfactant, while the hydrocarbon chains provide the hydrophobic environment. Sorbitol forms the backbone ring to which the ethylene oxide polymers are attached.


TWEEN 20 is widely used in biochemical applications. It has been used:
  • As an emulsifying agent for the preparation of stable oil-in-water emulsions
  • In pre-extraction of membranes to remove peripheral proteins (used at 2% for extraction of membrane-bound proteins)
  • As a blocking agent for membrane based immunoassays at a typical concentration of 0.05%
  • For lysing mammalian cells at a concentration of 0.005 to 0.5%
  • Along with PBS in the dilution of antibodies in immunohistochemistry technique
  • For washing cells in FISH (Fluorescence in situ hybridization) technique
Non-ionic detergent


50, 100 mL in poly bottle


TWEEN 20 may not be stable to autoclaving, particularly with metal cations in buffer solutions. Autoclaving is not recommended without testing for changes in properties. TWEEN 20 is heat sensitive and will darken when exposed to elevated temperatures. Polysorbates have been reported to be incompatible with alkalis, heavy metal salts, phenols, and tannic acid. They may also reduce the activity of many preservatives. Aqueous solutions of polysorbates undergo autoxidation during storage, with changes being catalyzed by light, increased temperature, and copper sulfate.

Preparation Note

TWEEN 20 is miscible in water (100mg/mL), yielding a clear, yellow solution. It is also miscible with alcohol, dioxane, and ethyl acetate. TWEEN 20 is insoluble in liquid paraffin and fixed oils.

Legal Information

TWEEN is a registered trademark of Croda International PLC

Personal Protective Equipment

dust mask type N95 (US),Eyeshields,Gloves


NONH for all modes of transport

WGK Germany


Flash Point(F)

527.0 °F - Pensky-Martens closed cup

Flash Point(C)

275 °C - Pensky-Martens closed cup

Telomere analysis by fluorescence in situ hybridization and flow cytometry.
Magnus H, et al.
Nucleic Acids Research, 26(16), 3651-3656 (1998)
Detergents: An Overview.
Neugebauer JM
Methods in Enzymology, 182, 239-253 (1990)
The role of transforming growth factor beta isoforms in tendon-to-bone healing
Kim H M, et al.
Connective tissue research, 52(2), 87-98 (2011)
Reynolds, J. E. F., (eds.)
Martindale: The Extra Pharmacopoeia, 1030-1030 (1993)
M Hultdin et al.
Nucleic acids research, 26(16), 3651-3656 (1998-08-01)
Determination of telomere length is traditionally performed by Southern blotting and densitometry, giving a mean telomere restriction fragment (TRF) value for the total cell population studied. Fluorescence in situ hybridization (FISH) of telomere repeats has been used to calculate telomere...
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