Hydrophilic Nonionic Surfactant Research Articles

Development and characterization of dexamethasone nanodispersion for the effective treatment of diabetic retinopathy

Diabetic retinopathy is the most common complication of diabetes and remains the leading cause of vision loss worldwide. The potent glucocorticoid based anti-inflammatory drug dexamethasone (DEX) chosen for the present work is long-acting with half-life of 37–72 h extensively metabolized in to 6-hydroxy-dexamethasone (6-OH-DEX). The present work aimed to develop dexamethasone loaded nanodispersion (DEX-ND) by improving its solubility, half-life, and bioavailability in biological system thereby this formulation may be afforded economically. With the concept that polymeric surfactant improves the solubility of challenging water insoluble drug the present work has been hypothesized to improve its solubility using polyvinyl pyrrolidone (PVP-K30) polymer and polysorbate 80 (Tween 80) hydrophilic non-ionic surfactant, thereby the bioavailability is expected to get enhanced. By varying the PVP K30 and Tween 80 concentrations three different formulations were developed. The developed DEX-ND was further characterized for its compatibility, particle size, zeta potential, morphology, and in vitro release behavior. The results of Fourier transform infrared spectrometric analysis indicate the compatibility nature of DEX-ND along with other excipients/drug used in the formulation. The developed formulations showed spherical morphology, particle size ranging from 550.46 ± 107.82 to 3560 ± 284.29 nm, zeta potential ranging from −29.23 ± 1.09 to −7.793 ± 1.01 mV. The amount of DEX present in the DEX-NDs was found to be 0.95–3.93 mg. The in vitro release studies as performed by dialysis bag method showed a sustained release pattern. The results of ex vivo corneal permeation studies indicates that the developed DEX- NDs has some exposure to the posterior segment of the eye.

New Lyotropic Complex Fluid Structured in Sheets of Ellipsoidal Micelles Solubilizing Fragrance Oils.

New lyotropic, fragranced, viscoelastic fluid with a complex structure is obtained from fragranced microemulsions by the addition of a fatty acid. Nonhomogeneous mixing of an appropriate nonionic surfactant, a fatty acid, and a fragrance oil led to the formation of anisotropically shaped and highly oriented micelles in aqueous solution. The nano- and microstructures, and consequently the viscosity, are controlled by the balance of fatty acids used as a cosurfactant and fragrance molecules, which partly behave as a cosurfactant and partly segregate in the micelles of the hydrophilic nonionic surfactant. The transition from isotropic microemulsion to a more structured viscoelastic solution is characterized by X-ray scattering and rheological methods. Considering our X-ray scattering results, we propose a structure composed of planar sheets of ellipsoidal micelles arranged in a lamellar type of stacking. The complex structured, low viscous, transparent fluid is capable of solubilizing a fragrance inside the ellipsoidal micelles, as well as retaining microparticles containing fragrance, without the addition of a polymeric thickener or another gelator. These features allow the creation of a 2-in-1 fragrance-solubilizing liquid product compatible with all types of home and body care consumer products.

Efficacy of a resveratrol nanoformulation based on a commercially available liposomal platform

Scalability is one of the important factors slowing down or even impeding the clinical translation of nanoparticle-based systems. The latter need to be manufactured at a high level of quality, with batch-to-batch reproducibility, and need to be stable after the manufacturing process, during long-term storage and upon clinical administration. In this study, a vesicular formulation intended for cutaneous applications was developed by the easy reconstitution of a commercially available liposomal platform. Resveratrol, a naturally occurring compound with potent antioxidant activity, and Tween80, a hydrophilic non-ionic surfactant, were included in the formulation. The physico-chemical properties of the vesicles were assessed using light scattering and cryogenic transmission electron microscopy. Nanosized (around 80 nm) spherical and elongated, unilamellar vesicles were produced, with remarkable storage stability. The incorporation of resveratrol in the vesicular system did not alter its strong antioxidant activity, as demonstrated by antioxidant colorimetric assays (DPPH and FRAP). Furthermore, the resveratrol liposomes were cytocompatible with fibroblasts and capable of protecting skin cells from oxidative stress by reducing both endogenous and chemically induced reactive oxygen species more effectively than free resveratrol. Therefore, the proposed formulation, based on the use of a commercially available liposomal platform, represents an easy-to-prepare, reproducible, up-scaled and efficient means of delivering resveratrol and potentiating its biological activity in vitro.

Tailoring surface properties of polyethylene terephthalate by atmospheric pressure plasma jet for grafting biomaterials

Tailoring surface hydrophilicity on polyethylene terephthalate (PET) by a radio frequency (RF) atmospheric pressure plasma jet (APPJ) for grafting biomaterials was investigated in this study. Two thermally responsive biomaterials of hydrophilic non-ionic surfactant of polyoxyethylene polymer and hydroxypropyl cellulose were used, while hydroxyethylmethacrylate (HEMA) was applied as the carrier for drug release. As applying the RF power in an APPJ system, PET substrates represented a tendency from an originally hydrophobic surface to a hydrophilic one, while apparent damaged areas were observed as the RF power exceeded 200 W. APPJ-induced polar functional groups onto PET surface without serious etching were most likely to improve the surface hydrophilicity for further grafting biomaterials. The grafted polyoxyethylene polymer on APPJ-treated PET substrates exhibited a surface change from opaque into transparent as the ambient temperature exceeded lower critical solution temperature of 37°C, while hydroxypropyl cellulose displayed a change from transparent into milky white as the temperature over 55°C. For the drug release behavior of aspirin on APPJ-treated PET substrates, the cumulative release rate of aspirin entrapped substrate for 3 h was 22%. Our results suggest that tailoring surface hydrophilicity of PET substrates without surface etching by 100W-APPJ process possessed a higher surface energy with a higher polar interaction, resulting in a good bonding with the grafted biomaterials.

EFFECT OF PEGYLATED EDGE ACTIVATOR ON SPAN 60 BASED- NANOVESICLES: COMPARISON BETWEEN MYRJ 52 AND MYRJ 59

In recent years, Span 60 based nanovesicles have been the object of growing scientific attention as an alternative potential drug delivery system to conventional liposomes. Surface modification of nanovesicles can adjust the drug release rate and the affinity for the target site. The aim of present work was firstly to study the effects of different PEGylated edge activator (Myrj 52 and Myrj 59) on Span 60 based nanovesicles. Nanovesicles were prepared using Span 60 alone or in combination with Myrj 52 (polyethylene glycol 2000 monostearate) or Myrj 59 (polyethylene glycol 4400 monostearate) by employing the ethanol injection method. Myrj 52and Myrj 59 are hydrophilic nonionic surfactants were used to modify the surface of the developed vesicles. Dynamic light scattering was used to determine the size, zeta potential and polydispersity index of the nanovesicles formulation. The vesicles were also characterized for entrapment efficiency and in vitro release. In current work, the modified nanovesicles size (ranging from 54.32 to 141.7 nm), zeta potential (ranging from -5.67 to -27.1 mV) and polydispersity index (ranging from0.248 to 0.531) indicated that the surface modified nanovesicles vesicles are a homogenous and mono-disperse nanovesicles dispersions. The non-modified nanovesicles are showed higher particles size (>2 times) compared to modified nanovesicles. The modified nanovesicles were showed entrapment efficiency ranging from 36.42 to 78.13 %. All the modified nanovesicles showed accepted in vitro release of TN from nanovesicles (>70% released after 8 h), followed Higuchi models as drug release mechanism. In conclusion, these surface modified nanovesicles could be used as a potential drug carrier for a variety of drugs.

Rational design of polysorbate 80 stabilized human serum albumin nanoparticles tailored for high drug loading and entrapment of irinotecan

Human serum albumin (HSA) nanoparticles are considered to be versatile carrier of anticancer agents in efficiently delivering the drug to the tumor site without causing any toxicity. The aim of the study was to develop stable HSA nanoparticles (NPs) of drug irinotecan (Iro) having slightly water solubility and moderate HSA binding. A novel strategy of employing a hydrophilic non-ionic surfactant polysorbate 80 which forms protein-polysorbate 80 complex with increased affinity and improvement in Iro-HSA binding has been used to maximize the loading and entrapment efficiency of Iro in HSA-NPs. Bespoke nanoparticles with entrapment efficiency (79.09%) and drug loading of 9.62% could be achieved with spherical shape and particle size of 77.38 nm, 0.290 polydispersity index and −23.7 mv Zeta potential. The drug entrapment in nanoparticles was confirmed by Differential Scanning Calorimeter, Fourier Transformation Infrared Spectroscopy and Fluorescence Spectroscopy. In vitro release of Iro from NPs showed biphasic-release with initial burst followed by prolonged release upto 24 h. The short-term stability investigation of nanodispersion showed no significant changes in physicochemical properties of NPs. Long-term studies on freeze dried Iro-HSA-NPs indicated good stability of NPs up to 12 months. This is the first report for efficient fabrication of Iro delivery system based on HSA nanoparticles.

Characterization of ternary compound viscosity reducer system on viscosity of viscous crude oil

ABSTRACTBased on the theory that viscous crude oil can form stable two-phase oil-water interfacial molecular membrane with surfactant, the oil-water interfacial activity and viscosity reduction of oil-water interface of viscous crude oil were studied for the ternary compound system, including anionic surfactant alpha olefin sulfonate (AOS), weak alkali Na2CO3 and four different kinds of nonionic surfactant emulsifying silicon oil (LKR-1023), lauryl diethanolamide (LDEA), isomeric alcohol ethoxylates (E-1306), and polyoxyethylene sorbitan monooleate (T-80). Results showed when lipophilic or hydrophilic nonionic surfactants were used separately in the same compound system. The viscosity of viscous crude oil could be reduced, but the viscosity reduction efficacy was not desirable. However, using LKR-1023, E-1306, and T-80 as nonionic surfactant with mass fraction 1.0%, the viscosity reduction rate of viscous crude oil reaches 98.92%, 98.29%, and 96.87%, respectively. With 1.4% of LDEA, the viscosity reduction rate of viscous crude oil can reach 98.89%. Through all different kinds of the nonionic surfactant tested, oil-in-water (O/W) emulsion under LDEA ternary compound system has been proved to be the most stable with no phase inversion. Therefore, it is promising to improve the viscosity reduction of the super viscous crude oil by selecting the proper surfactant and dosage.

Emulsification of viscous alkyd resin by catastrophic phase inversion with nonionic surfactant

The addition of water to hydrophobic alkyd resin containing a hydrophilic nonionic surfactant (polyethoxylated-20-oleyl alcohol) was used to produce the emulsion morphology change from W/O to O/W in a small thermostated reactor (50mL). The so-called catastrophic phase inversion of the water/alkyd resin system was detected by monitoring both, the viscosity by torque measurement and the electrical conductivity, until an equal weight fraction of water and resin is attained (fw=0.5). The two methods provide similar values of the phase inversion point (PIP). Although the determination of the PIP exhibits a small inaccuracy, it is clear that different torque profiles and PIP are observed depending on the resin neutralization level, the surfactant concentration and the water addition rate. For the non-neutralized resin, both, PIP and emulsion drop size, decrease with surfactant concentration increase. The completely neutralized resin could be emulsified using a minimum of 2wt% of surfactant in the final emulsion. In such a case the water fraction at which inversion occurs (fw,Inv=0.36) is independent of the surfactant concentration and a small resin drop diameter (<200nm) can be obtained. A more precise study of the reached drop size of the emulsion versus resin neutralization (0, 25, 50, 75, 100 and 125%) indicates that a minimum diameter is obtained around 90–100% neutralization, with no effect of over-neutralization. For non-neutralized resin a maximum fw,Inv (0.25) can be obtained by reducing water addition rate allowing the production of 0.5μm droplets in a longer process.

Fabrication of nickel nanoparticles modified electrode by reverse microemulsion method and its application in electrolytic oxidation of ethanol

This paper highlights recent work on formulation and stability of nickel sulphate W/O microemulsion using hydrophilic nonionic surfactant Tween 80, and its use for electrodeposition of uniform Ni-nanoparticles on nickel plating. The prepared microemulsion was found to be crystal clear and very stable for more than 30 days at a wide range of temperature (20≥T≤45°C). The Tween 80/n-hexane/n-hexanol/water microemulsion was used for fabrication of nickel nanoparticles modified nickel electrode. These electrodeposited Ni-nanoparticles were characterized by SEM, which revealed that uniform spherical nanoparticles of diameter 100–160nm were deposited on electrode surface. The Ni-nanoelectrode was applied for electrooxidation of alcohols. The catalytic efficiency of Ni-nanoelectrode was far better than bulk electrode due to its high surface area.

Synergism Between Alkylbenzene Sulfonate and Nonionic Surfactant for Producing Low Interfacial Tension at Oil/Water Interface

Synergism between alkylbenzene sulfonate and nonionic surfactant was studied by measuring interfacial tensions of surfactants and their mixtures against a homologous series of alkanes. Four di-n-alkylbenzene sulfonate homologues and a nonionic surfactant, lauryl alcohol polyoxyethylene(9) ether, were used. Effects of hydrophilic-lipophilic ability of surfactant, mixing ratio, and salinity of aqueous phase on synergism were investigated. It is found that the synergism for producing low interfacial tensions derives from the change of the hydrophilic-lipophilic abilities of the surfactant systems from the individual surfactants to their mixtures, which is confirmed by analyzing the alkane scanning curves, and the method to achieve synergism is adding the hydrophilic nonionic surfactant to the lipophilic alkylbenzene sulfonate, and ultralow interfacial tensions (<0.01 mN/m) can be obtained in proper mixing ratios. The results are of great significance for enhanced oil recovery.

Effect of nonionic surfactant addition on Pyrex glass ablation using water-assisted CO2 laser processing

Pyrex glass etching using laser ablation is an important technology for the microfluid application to lab-on-a-chip devices but suffers from the formation of surface crack. In this article, the addition of nonionic surfactant to water for glass ablation using water-assisted CO2 laser processing (WACLAP) has been investigated to enhance ablation rate and to eliminate conventional surface defects of cracks in air. WACLAP for Pyrex glass ablation can reduce thermal-stress-induced crack with water cooling and hydrophilic nonionic surfactant to water can enhance ablation performance. Compared to pure water, the 15% weight percent Lauramidopropyl Betaine surfactant solutions for WACLAP can enhance ablation rate from 13.6 to 25 μm/pass of Pyrex glass ablation at a linear laser energy density of 2.11 J/cm, i.e., 24 W power, 114 mm/s scanning speed, and obtain through-wafer etching at 3.16 J/cm for 20 passes without cracks on the surface. Effect of surfactant concentration and linear energy density on WACLAP was also examined. The possible mechanism of surfactant-enhanced phenomenon was discussed by the Newton’s law of viscosity of surfactant solution.

A Closed Concept of Extractive Whole Cell Microbial Transformation of Benzaldehyde into l-Phenylacetylcarbinol by Saccharomyces cerevisiae in Novel Polyethylene-Glycol-Induced Cloud-Point System

Extractive microbial transformation of benzaldehyde into L-phenylacetylcarbinol (L-PAC) by Saccharomyces cerevisiae (Baker's yeast) has been carried out in a novel polyethylene-glycol-induced cloud-point system (PEG-CPS). The extractive microbial transformation in the PEG-CPS and a downstream process for stripping of the product from the microbial transformation broth with microemulsion extraction are demonstrated. The results indicate that the PEG-CPS maintains the advantage of CPS for in situ extraction of polar product in the microbial transformation. At the same time, the utilization of hydrophilic nonionic surfactant in the PEG-CPS is favorable for stripping of product from the nonionic surfactant in the microbial transformation broth by Winsor I microemulsion extraction. Thus, a closed concept of in situ extraction of polar product in microbial transformation and its downstream process of product recovery are fulfilled at the same time.

Novel polyethylene glycol induced cloud point system for extraction and back-extraction of organic compounds

A novel polyethylene glycol (PEG) induced cloud point system (PEG-CPS) with high hydrophile–lipophile balance (HLB) value nonionic surfactant and high molecular weight PEG had been developed for extraction of organic compounds. The main advantage of this novel system is that the back extraction process of stripping of nonvolatile organic compounds from the nonionic surfactant aqueous solution can be carried out with Winsor I microemulsion extraction. Thus a separation of organic compounds from the nonionic surfactants in aqueous solution become possible, which is potential for cloud point extraction (CPE) or extractive microbial transformation in cloud point system from economical and environmental consideration. With Triton X-100 as a model hydrophilic nonionic surfactant, the phase diagram of PEG-CPS was determined. High boiling point organic compounds, such as phenol, p-nitrophenol and 1-naphthol phenol, were extracted with PEG-CPS. Then the organic compounds in the surfactant rich phase of PEG-CPS were back-extracted with microemulsion.

Preparation of tiny biodegradable capsules using electrocapillary emulsification

Conditions for preparing tiny biodegradable capsules were examined using electrocapillary emulsification that allows one to prepare monodisperse emulsions with ease by applying a DC potential between oil and water phases without mechanical agitation. The results obtained showed that a 1 : 4 mixture of polysorbate 80 (TO-10), a hydrophilic non-ionic surfactant, and sorbitan monooleate (SO-10), an oleophilic surfactant, is appropriate as the surfactant to be added to oil phase, cyclohexane is acceptable as the oil phase and 1000 V is optimum as the DC potential to be applied. The capsules prepared had sizes ranging from 100–300 nm and a surface roughness of ∼10 nm and degraded in model intestinal juice more easily and rapidly than in model gastric juice. In addition, the capsules containing lactoferrin, an anti-carcinogenic protein, were found to keep 12.5% of the protein used in encapsulation without losing its activity.

PLGA microcapsules with novel dimpled surfaces for pulmonary delivery of DNA

We describe the fabrication of DNA-loaded poly(lactic-co-glycolic acid) (PLGA) microcapsules with novel surface morphologies that will be of use in pulmonary delivery. Our approach was to examine surface morphology and DNA encapsulation efficiency as a function of primary emulsion stability; using two surfactant series based on hydrophile–lipophile balance and hydrophobe molecular weight. Hydrophilic non-ionic surfactants yielded the most stable water-in-dichloromethane emulsions (HLB values >8). These surfactants normally favor convex (o/w) interfacial curvatures and therefore this atypical behavior suggested a relatively high surfactant solvation in the dichloromethane ‘oil’ phase. This was consistent with the large fall in the glass transition temperature for microspheres prepared with Tween 20, which therefore efficiently penetrated the PLGA matrix and acted as a plasiticizer. Blends of Pluronic triblock copolymers performed poorly as water-in-dichloromethane emulsifiers, and were therefore used to generate hollow microspheres (‘microcapsules’) with low densities (0.24 g/cm 3). Although the Pluronic-stabilized emulsions resulted in lower DNA loading (15–28%), microspheres (∼8 μm) with novel dimpled surfaces were fabricated. The depth and definition of the dimples was greatest for triblock copolymers with high MW hydrophobe blocks. By cascade impaction, the geometric mean weight diameter of the microcapsules was 3.43 μm, suggesting that they will be of interest as biodegradable pulmonary delivery vehicles.

The Effect of Various Surfactants on Release Behavior of Procainamide HCl from Ethylcellulose Based Matrices

The effect of different kinds of surfactants in various concentrations incorporated in an inert matrix, on the release of procainamide hydrochloride, as a cationic model compound, was investigated in this study. Sodium lauryl sulfate and sodium stearate as anionic surfactants, cetyl pyridinium chloride and cetyltrimethyl ammonium bromide as cationic and span 60 and tween 80 as non-ionic surfactants were selected. Hydrophobic matrices were prepared using procainamide HCl, ethyl cellulose, dicalcium phosphate and different percentages of each surfactant and the dissolution rate of drug from various matrices was determined in pH values1.2 (for 2 h) and 7.2 (up to 10 h). The results showed that incorporation of anionic surfactants in matrix preparations resulted in a remarkable decrease in the release rate of procainamide HCl (P < 0.05), which was attributed to the formation of a poorly soluble complex between the cationic drug and the anionic surfactant. The formation of complex was confirmed by the precipitation titration test. On the other hand, presence of cationic surfactants considerably increased the drug release rate and it was noted that by raising the percentage of surfactant, a faster drug release rate release was achieved. With span 60 there was no change in drug release rate, probably due to its lower wetting capability. While in the case of tween 80, as a hydrophilic non-ionic surfactant, the drug release rate was increased, although statistically not significant. In general, it seems that the influence of cationic and non-ionic surfactants on drug release rate was in accordance with the ability of each surfactant in wetting the matrices and producing a greater number of channels for the dissolution fluid to leach out the drug. Kinetics evaluation of the release profiles showed that the Higuchi equation is the main model, fitting the data.

Enhancing the Biological Activity of Nicosulfuron with pH Adjusters1

Adjuvants that increase the pH of the spray mixture and solubilize nicosulfuron can enhance biological activity under specific conditions. These conditions include high nicosulfuron rates, difficult-to-control weeds, low spray volumes, and initially acidic spray conditions. The most effective pH adjusters are tribasic potassium phosphate, sodium carbonate, and triethanolamine. In low spray volumes, these adjusters make the spray mixture alkaline and often enhance the activity of nicosulfuron on common cocklebur and large crabgrass. Alkaline conditions rapidly dissolve the sulfonylurea particles and enhance activity with crop oil concentrate, modified seed oil, and hydrophilic nonionic surfactants. pH adjusters did not enhance activity with lipophilic surfactants. Ammonium sulfate slightly increases the pH of spray mixtures and increases nicosulfuron activity depending on species, adjuvant type, and pH adjuster. These results generally support the concept that herbicide solubilization is necessary to maximize the foliar activity.Nomenclature: Nicosulfuron; common cocklebur, Xanthium strumarium L. #3 XANST; large crabgrass, Digitaria sanguinalis (L.) Scop. # DIGSA.Additional index words: Adjuvant, basic blend, buffer, crop oil concentrate, fertilizer, formulation, hydrophilic–lipophilic balance, methylated seed oil, modified seed oil, nonionic surfactant, potassium phosphate, soda ash, sulfonylurea, triethanolamine, water-dispersible granule.Abbreviations: AMS, ammonium sulfate; COC, crop oil concentrate; HLB, hydrophilic–lipophilic balance; MSO, modified seed oil; NIS, nonionic surfactant; NPE, nonylphenol ethoxylate; TEA, triethanolamine; WDG, water-dispersible granule.

Effect of Electrolytes on Discontinuous Cubic Phases

We investigated the effect of adding a lyotropic salt (NaCl) and a hydrotropic salt (NaSCN) on the discontinuous cubic phase formed in highly hydrophilic nonionic (C12EO25) and ionic (DTAC) surfactant systems by phase study and small-angle X-ray scattering (SAXS) measurements. In C12EO25 systems, only a small decrease in the thermal stability of the cubic phase was observed upon addition of NaCl or NaSCN. It was also found that NaCl induces a slight reduction on the effective surface area per surfactant molecule (as), whereas in the case of NaSCN, as increases. These results are attributed to changes in the hydration of the poly(oxyethylene) (EO) chain. On the other hand, in DTAC systems, the addition of both NaCl and NaSCN leads to a transition from the discontinuous cubic phase to the hexagonal phase, related to a more pronounced shrinkage of as and to the micellar growth within the cubic phase. Changes in micellar structure resemble that occurring in diluted systems upon addition of salt. The stability...

A novel method for preparing oil‐in‐water‐in‐oil type multiple emulsions using organophilic montmorillonite clay mineral

AbstractA stable formula using oil‐in‐water‐in‐oil (O/W/O) type multiple emulsions was investigated. The components consisted of hydrophilic nonionic surfactant (HCO‐60), organophilic montmorillonite, and lipophilic nonionic surfactant (DIS‐14). O/W/O emulsions were prepared by a double‐step procedure in which an O/W emulsion was prepared in the first step, and then the O/W emulsion was “re‐emulsified” in an oil phase with organophilic montmorillonite. The diameter of the innermost oil droplets decreased with increasing HCO‐60 content (0.1–3%), while the viscosity showed a maximum at 1% of HCO‐60, indicating that the yiel of re‐emulsification is highest at this condition. Viscosity of the O/W/O emulsion increased with increasing organophilic montmorillonite and DIS‐14. According to the results of a phase ratio study, viscosity and stability of the O/W/O emulsion decreased at high weight fraction of inner oil phase (0.4–0.5), indicating that the excess amount of inner oil phase is absorbed by the outer oil phase. These results revealed that the weight fraction of inner oil phase should be kept below 0.3 for a stable O/W/O emulsion. A similar study on the weight fraction of O/W phase [фO/W)/O] suggested that the O/W/O emulsion is stable at ϕ(O/W)/O=0.65–0.70.

Contact allergenic activity of Tween 80 before and after air exposure.

Tween 80 is an ethoxylated hydrophilic non-ionic surfactant, which is used for the preparation of oil-in-water emulsions in pharmaceutical products, cosmetics, and industrial detergents. Ethoxylated surfactants are polyethers and are thus easily oxidized by atmospheric oxygen to a variety of hydroperoxides, peroxides and carbonyl compounds. The aim was to investigate the formation of oxidation products and the allergenic potential of Tween 80 before and after air exposure. The formation of peroxides and formaldehyde was followed with chemical analyses during air and pure oxygen exposure of water solutions of Tween 80 of technical quality. A complex mixture of compounds was formed when Tween 80 was oxidized. Formaldehyde was detected in amounts that may be eliciting in allergic individuals. Acetaldehyde was identified in Tween 80 before oxygen exposure, whereafter the amount gradually decreased. The contact allergenic activity was determined in experimental sensitization studies in guinea pigs. Non-oxidized as well as oxidized Tween 80 of technical quality showed allergenic activity. The results indicate that allergens are present in Tween 80 before oxidation and that new allergens are formed in the oxidation process. No obvious dose-response relationship was found in the sensitization studies. The possibility that allergenic compounds can be formed during storage and handling of products containing ethoxylated surfactants should be taken into consideration.