Polyethylene Glycol Mono-4-octylphenyl Ether (n≈10): Guide

What is Polyethylene Glycol Mono-4-octylphenyl Ether (n=approx. 10), and why does it matter?

Polyethylene Glycol Mono-4-octylphenyl Ether (n=approx. 10), CAS 9002-93-1, is a nonionic surfactant. Its molecule consists of a hydrophobic 4-octylphenyl group and a hydrophilic polyethylene glycol (PEG) chain. The "n=approx. 10" indicates the average number of ethylene oxide units per molecule. The material is a mixture of oligomers with chain lengths that vary around this value, not a single compound. In the laboratory, it is often associated with Triton X-100, a trade name owned by another company (a registered trademark of Dow).

It matters because it can solubilize lipid membranes and keep hydrophobic proteins dispersed without changing the electrical charge of the solution. Its nonionic character makes it "gentler" on protein structure than ionic surfactants such as SDS. For this reason, it is found in almost every biochemistry, molecular biology, and analytical laboratory.

The TCI catalog code for this material is P0873.

Properties that determine experimental outcomes

Understanding the following properties will help keep your results on track.

Amphiphilic structure and CMC. Above the critical micelle concentration (CMC), the molecules form micelles. The CMC of this material is in the sub-millimolar range, which is low. Membrane solubilization generally occurs above the CMC, while gentle washing can be done at lower concentrations. Because the CMC is low, this surfactant is difficult to remove by dialysis. If residual surfactant interferes with your work, plan to clean up the sample by another method.

PEG chain length distribution. Because n is only an average, the chain distribution also helps determine the hydrophilic–lipophilic balance (HLB), micelle size, and cloud point. Differences in distribution between batches can shift lysis efficiency or emulsion stability.

Cloud point. When heated past a certain temperature (the cloud point), the solution turns cloudy and separates into phases. For this type of surfactant, that temperature is in the range of the 60s °C. High-temperature treatments, such as autoclaving or hot incubation, can trigger phase separation. Salt concentration and other additives also shift the cloud point.

UV absorbance. The aromatic ring in the octylphenyl group absorbs UV light at around 280 nm. If you measure protein by A280, this surfactant can raise the background. Use a blank containing the surfactant at the same concentration, or choose another quantification method.

Viscosity and hygroscopicity. The neat material is fairly viscous at room temperature and difficult to pipette accurately. It also tends to absorb moisture. Careless weighing or pipetting leads to stock concentrations that deviate from the intended value.

Tendency to form peroxides. Like other polyglycol ethers, the polyethylene oxide chain can slowly oxidize on exposure to air and light. Oxidation products (peroxides, aldehydes) can oxidize protein thiol groups or interfere with enzymes.

Laboratory uses and the material's role in each application

Cell lysis and protein extraction. The material dissolves plasma membrane lipids so that the cell contents are released. Its role is that of a membrane-solubilizing detergent. Lysis buffers for immunoprecipitation and Western blot often include it because it generally does not denature protein complexes.

Membrane protein solubilization. The surfactant replaces the lipids around the transmembrane domain, so the protein stays dissolved in micelles. Its role is to keep hydrophobic proteins from aggregating. For each target, the concentration and the detergent-to-protein ratio still need to be optimized.

Permeabilization in immunofluorescence and immunocytochemistry. At low concentrations, the material creates pores in the membranes of fixed cells so that antibodies can enter. Its role is that of a permeabilization agent. Overly long incubation can damage cell morphology.

Wash and blocking buffers. In ELISA and immunoblotting, a small amount of surfactant reduces nonspecific binding and keeps surfaces wetted. Its role is to reduce background. Other nonionic surfactants are also commonly used for this function, so follow the protocol you have validated.

Nucleic acid extraction and reaction additive. In some DNA extraction protocols or cell lysis steps for PCR, the surfactant helps open cells and dissolve lipids. Its role is as a lysis aid. Excess residue can inhibit enzymes, so pay attention to the final concentration in the reaction.

Dispersion and materials synthesis. In the synthesis of nanoparticles, emulsions, and colloidal formulations, the material works as an emulsifier and stabilizer that reduces interfacial tension. It is also used as a cleaning or wetting agent for glassware and surfaces.

Research on the physical properties of fluids. Because it is an oligomer, the material is also the subject of solution thermodynamics studies, as discussed in the next section.

What does recent research say?

The references below mainly concern the material's physical properties, not biological protocols. Only a general overview is summarized here, not measured values.

  • "Pvt Properties of Binary Systems of Poly(Ethylene Glycol Mono-4-Octylphenyl Ether) with Anisole or Benzyl Alcohol at Pressures Up to 50 Mpa" (2022, SSRN Electronic Journal) examined the pressure–volume–temperature (PVT) behavior of binary systems of this material with anisole or benzyl alcohol at pressures up to 50 MPa. DOI: 10.2139/ssrn.4196920.
  • "Pressure-volume-temperature properties for binary oligomeric solutions of anisole with polyethylene glycol mono-laurate or polyethylene glycol mono-4-nonylphenyl ether" (2023, Fluid Phase Equilibria) continues the PVT study of binary oligomeric solutions with anisole, comparing PEG monolaurate with PEG mono-4-nonylphenyl ether. This compound is an analog of the material in this article (the alkyl group on the phenyl ring differs), so its relevance is indirect. DOI: 10.1016/j.fluid.2022.113661. A preprint version with a similar title, which also covers PEG mono-4-nonylphenyl ether, is available on SSRN (2022), DOI: 10.2139/ssrn.4229648.
  • "Pressure-volume-temperature properties for binary oligomeric blends of polyethylene glycol mono-laurate with polyethylene glycol mono-4-octylphenyl ether" (2019, The Journal of Chemical Thermodynamics) studied binary blends of these two PEG oligomers. DOI: 10.1016/j.jct.2019.03.038.

The practical takeaway: the physical properties of this material, such as density and volume at various temperatures and pressures, depend on the composition and the partner solvent. Behavior measured in one mixture cannot be assumed to apply directly to another.

Why does TCI quality matter for this material?

TCI is a Japanese chemical manufacturer, and AMI Scientific is its official distributor in Indonesia. For an oligomeric surfactant like this, quality directly affects experimental results.

Purity and impurities. Relevant impurities include peroxides and carbonyl compounds from oxidation of the PEG chain, as well as interfering aromatic compounds. Peroxides can oxidize protein cysteine residues or inactivate enzymes, so activity drops for no obvious reason. Aromatic impurities raise the A280 background.

Batch-to-batch consistency. Because this material is a mixture of oligomers, the chain length distribution must be consistent. A shift in distribution changes the effective CMC, cloud point, and lysis efficiency. As a result, a protocol that has already been optimized can give different results when the batch changes. For ongoing experiments or QC work, this consistency is what makes data comparable over time.

Analytical documentation. Check the specifications and the certificate of analysis (CoA) for each batch. This documentation lets you trace the batch used if results suddenly change, and it supports method validation records.

Packaging. A material that is viscous, hygroscopic, and sensitive to oxidation deteriorates faster if the bottle is opened often. Choose a pack size that matches your rate of use so the material is not exposed to air and light for long.

Choosing the product form. TCI offers several variants:

Make sure the grade fits your needs, and read the specifications on each product page.

Handling and storage

  • Read the SDS before working. Materials of this type can generally cause serious eye damage, are harmful if swallowed, and are toxic to aquatic organisms. Wear gloves, safety glasses, and a lab coat.
  • Pipette the viscous material slowly, or use a positive-displacement pipette. For a 10% (w/v) working stock, prepare the solution by weighing and dissolving slowly in water, without vigorous shaking so it does not foam. Gentle warming can speed up dissolution, but do not go past the cloud point.
  • Store in a tightly closed container, in a cool, dry place, protected from light and away from strong oxidizers. Close the bottle immediately after use.
  • Record the date the bottle was opened. Material that has been open for a long time risks containing peroxides. For sensitive applications such as enzyme work or thiol-rich proteins, use a relatively new bottle.
  • Stock solutions should be kept in clean containers and labeled with the preparation date. Discard if they look cloudy at room temperature or change color.
  • Waste must not be poured down the drain. Collect it as chemical waste according to your laboratory's procedures.

Quick FAQ

Is this material the same as Triton X-100?

Triton X-100 is a trade name owned by another company (a registered trademark of Dow) for an octylphenol ethoxylate surfactant with an average of about 10 ethylene oxide units. Its chemical description is similar to that of this material, but the two cannot simply be declared identical, because chain distribution and impurity profile can differ between manufacturers and batches. Check the specifications and CoA if you need to confirm suitability for a particular protocol.

Why does my solution turn cloudy when heated?

You have probably passed the cloud point. Lower the temperature, and the solution will generally become clear again. The presence of salt can lower the cloud point.

Can I use it when measuring protein by A280?

Yes, but the surfactant absorbs UV. Use a blank with the same surfactant concentration, or a quantification method that is not affected.

Which should I choose: the neat material or the 10 w/v% solution?

The neat material is more flexible for making various concentrations. The 10 w/v% solution is more practical and reduces pipetting errors, making it suitable for routine molecular biology work.

How do I remove the surfactant from a sample?

The low CMC makes dialysis less efficient, and diluting the sample does not remove detergent. Consider detergent-adsorbing resins, protein precipitation (for example with acetone or TCA), or detergent exchange by chromatography, according to your application's tolerance. Keep in mind that precipitation generally denatures proteins.

Conclusion

Polyethylene Glycol Mono-4-octylphenyl Ether (n=approx. 10) looks simple, but its oligomeric nature, tendency to oxidize, and viscosity can change your results if ignored. Choose the product form that suits your application, check the CoA for each batch, and store it properly. For other TCI product needs or technical questions, the AMI Scientific team is ready to help.

References

  1. Pressure-volume-temperature properties for binary oligomeric solutions of anisole with polyethylene glycol mono-laurate or polyethylene glycol mono-4-nonylphenyl ether at pressures up to 50MPa. Fluid Phase Equilibria, 2023. DOI: 10.1016/j.fluid.2022.113661
  2. Pressure-Volume-Temperature Properties for Binary Oligomeric Solutions of Anisole with Polyethylene Glycol Mono-Laurate or Polyethylene Glycol Mono-4-Nonylphenyl Ether at Pressures Up to 50 Mpa. SSRN Electronic Journal, 2022. DOI: 10.2139/ssrn.4229648
  3. Pvt Properties of Binary Systems of Poly(Ethylene Glycol Mono-4-Octylphenyl Ether) with Anisole or Benzyl Alcohol at Pressures Up to 50 Mpa. SSRN Electronic Journal, 2022. DOI: 10.2139/ssrn.4196920
  4. Pressure-volume-temperature properties for binary oligomeric blends of polyethylene glycol mono-laurate with polyethylene glycol mono-4-octylphenyl ether or polyethylene glycol mono-4-nonylphenyl ether at pressures up to 50 MPa. The Journal of Chemical Thermodynamics, 2019. DOI: 10.1016/j.jct.2019.03.038
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