Stability of orange oil/water nanoemulsions prepared by the PIT method

This article reports the preparation and characterization of orange oil/water nanoemulsions stabilized by commercial nonionic surfactants based on ethoxylated lauryl ether (Ultrol line), by the phase inversion temperature (PIT) method. The orange oil/surfactant/water dispersions were prepared at different HLB values, by varying the concentrations of the surfactants as well as the concentration of the oil phase. The stability of the o/w nanoemulsions and the size distribution of the dispersed particles in these systems in general depended on the concentration of the oil phase used: the emulsions prepared with an oil phase of 14 wt% had smaller droplet size in the dispersed phase than the emulsions prepared in the presence of oil phases of 20 and 30 wt%. The nanoemulsions prepared with pure surfactants were more stable in the presence of Ultrol L60, but the surfactants' cloud point had a strong influence on the stability of the emulsions formed when this was very near room temperature. Because of this, we prepared systems containing mixtures of surfactants. Among these systems, the most stable nanoemulsions were those prepared with a Ultrol L100/Ultrol L20 mixture with HLB of 12.40. This behavior can be attributed to the complete solubilization in mixed micelles of the more hydrophobic surfactant.     

Proposal of a sequential treatment methodology for the safe reuse of oil sludge-contaminated soil

In this study sequential steps were used to treat and immobilize oil constituents of an oil sludge-contaminated soil. Initially, the contaminated soil was oxidized by a Fenton type reaction (13 wt% for H(2)O(2); 10mM for Fe(2+)). The oxidative treatment period of 80 h was carried out under three different pH conditions: 20 h at pH 6.5, 20 h at pH 4.5, and 40 h at pH 3.0. The oxidized contaminated sample (3 kg) was stabilized and solidified for 2h with clay (1 kg) and lime (2 kg). Finally, this mixture was solidified by sand (2 kg) and Portland cement (4 kg). In order to evaluate the efficiency of different processes to treat and immobilize oil contaminants of the oil sludge-contaminated soil, leachability and solubility tests were performed and extracts were analyzed according to the current Brazilian waste regulations. Results showed that the Fenton oxidative process was partially efficient in degrading the oil contaminants in the soil, since residual concentrations were found for the PAH and BTEX compounds. Leachability tests showed that clay-lime stabilization/solidification followed by Portland cement stabilization/solidification was efficient in immobilizing the recalcitrant and hazardous constituents of the contaminated soil. These two steps stabilization/solidification processes are necessary to enhance environmental protection (minimal leachability) and to render final product economically profitable. The treated waste is safe enough to be used on environmental applications, like roadbeds blocks.     

Nanoemulsions containing octyl methoxycinnamate and solid particles of TiO2: preparation,characterization and in vitro evaluation of the solar protection factor

The objective of this work was to develop and evaluate the physical–chemical properties of oil-in-water nanoemulsions for application as nanocosmetics for sun protection. Oil-in-water dispersions were processed by ultrasound (US) to obtain small emulsion droplets. These emulsions were obtained in the presence of commercial nonionic surfactants based on polyoxides and avocado oil as the oil phase. The US generated small but unstable droplets. This problem was solved by using a different surfactant, with a longer ethylene oxide chain, able to promote stabilization by steric mechanisms. The light scattering technique was used to characterize the nanoemulsions by their dispersed droplets’ size, size distribution and variation of distribution with time (stability). Chemical and physical sunscreens – octyl methoxycinnamate (OMC) and titanium dioxide (TiO₂), respectively – were added to the stable system. The anti-UVB activity of the nanoemulsions and their components were evaluated by the method of Mansur et al. (1986) and spectral transmittance. The solar protection factor (SPF) was proportional to the OMC and TiO₂ concentrations. The in vitro OMC release was evaluated, and the presence of TiO₂ in the nanoemulsion did not affect the release profile, which showed the diffusion-dependent kinetics of the active ingredient in the formulation.     

Jaboticaba (Plinia peruviana) extract nanoemulsions: development,stability, and in vitro antioxidant activity

Objective: The aim of this work is to develop and characterize nanoemulsions containing jaboticaba extract (Plinia peruviana) aiming pharmaceutical and cosmetic applications.

Methods: Nanoemulsions were prepared by high-pressure homogenization method using different concentrations of components (oil, surfactant, and extract) and homogenization pressures, in order to optimize the preparation conditions. Both unloaded and extract-loaded nanoemulsions were characterized according to their size, polydispersity, zeta potential, pH, morphology, and physical stability. Total phenolic and flavonoid contents in free jaboticaba extract and jaboticaba-loaded nanoemulsions were determined spectrophotometrically, while ellagic acid content was determined by high-performance liquid chromatography (HPLC) analysis. In vitro antioxidant activity was investigated by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) methods.

Results: Colloidal dispersions exhibited a mean particle size around 200?nm, with monodisperse size distribution (PdI <0.3), and spherical shape. Stability studies showed that nanoemulsions were stable over 120?d of storage at room temperature. Jaboticaba nanoemulsions showed significant concentrations of phenolics, flavonoids, and ellagic acid, with encapsulation efficiency values higher than 90%. Antioxidant properties of jaboticaba nanoemulsions were demonstrated by its remarkable ability to scavenge DPPH free radicals and to reduce ferric–tripyridyltriazine complex, which can be attributed to their phenolic and flavonoid contents.

Conclusions: The results suggest that nanoemulsions containing jaboticaba extract can be considered a promising candidate as a new antioxidant agent.     

Formation of drug-loaded nanoemulsions in stirred media mills

The feasibility of stirred media mills for the production of nanoemulsions loaded with active pharmaceutical ingredients (API) using plant oils as disperse phase and different types of the non-ionic emulsifier polysorbate is demonstrated. The influence of the emulsion formulation, namely oil type, surfactant and surfactant-to-oil-weight-ratio (SOR) on the product droplet size at constant stressing conditions is studied in detail. At similar stressing conditions and SOR, the type of the used plant oil and surfactant did not influence the product droplet size and the smallest achievable median droplet size was 20 nm. The API saturated oil phases and the pure oil phases exhibit similar viscosities, emulsification kinetics and final product droplet sizes, i.e. no influence of the API on the emulsification process could be identified. However, a strong dependency of the emulsion droplet size on the SOR has been observed. Moreover, very good long-term stabilities could be achieved for the obtained emulsions. A release test with fenofibrate-loaded peanut oil-polysorbate 80-water nanoemulsions showed remarkably fast drug distribution as compared to a formulation containing the same amount of the non-dissolved micronized drug.     

莫来石与碳纤维协同填充的聚四氟乙烯基复合材料及其摩擦学性能

为了提高聚四氟乙烯（PTFE）的摩擦学性能,采用机械混匀、带温预压及烧结等工艺制备了莫来石和碳纤维填充的PTFE基复合材料,并通过FTIR、XRD、万能材料试验机、洛氏硬度计、DSC及热机械分析分别表征了PTFE基复合材料的显微结构、力学性能和热学性能;然后,使用MRH-3 型高速环块磨损试验机测定了复合材料的摩擦系数和磨损率,通过自制的硅油砂浆磨损装置测定了复合材料在不同温度下的耐砂浆磨损性能;最后,借助3D测量激光显微镜研究了复合材料摩擦面形貌,并分析了摩擦磨损机制。结果表明:莫来石和碳纤维在PTFE体系中起到填充增强作用,20wt%莫来石-10wt%碳纤维/PTFE复合材料的弹性模量由364 MPa增加至874 MPa;20wt%莫来石-10wt%碳纤维/PTFE复合材料的干摩擦系数较大,但其磨损率与纯PTFE相比降低了3个数量级以上,且此复合材料在水摩擦条件下仍能保持较好的摩擦系数和磨损率,摩擦系数为0.157,磨损率为7.40×10-6 mm3·N-1·m-1;此外,20wt%莫来石-10wt%碳纤维/PTFE复合材料在较高温度下仍能表现出良好的耐砂浆磨损性能。所得结论表明改性得到的PTFE 基复合材料的摩擦学性能显著提高,复合材料可用于有杆抽油井防偏磨。      

Physicochemical characterization of rutaecarpine-loaded microemulsion system

To develop an o/w microemulsion system containing poorly water-soluble rutaecarpine, the solubility of rutaecarpine in water, ethanol, various oils, and surfactants were investigated. Among the surfactants and oils tested, Tween 20/PEG 400 and castor oil were chosen as the surfactant system and oil phase of the microemulsion, as rutaecarpine was most soluble in them, respectively. Pseudoternary phase diagrams were constructed to obtain the concentration range of oil, surfactant, and cosurfactant for microemulsion formation, and the stability test of rutaecarpine delivered by microemulsion formation was then evaluated. Pseudoternary phase diagrams show that the areas of microemulsion appeared at those with 0-20% Smix (PEG 400/Tween80 = 60/40), 64-81% water, and 10-20% oil. The rutaecarpine (300 µg/g)-loaded microemulsion composed of 10.8% PEG 400, 7.2% Tween 80, 20% caster oil, and 72% water was physically and chemically stable for at least 6 months. Thus, the microemulsion system composed of castor oil, PEG 400, Tween 80, and water could be a stable dosage form for rutaecarpine.     

Enhanced transdermal delivery of carvedilol using nanoemulsion as a vehicle

The aim of the present study was to develop nanoemulsion as a possible vehicle for enhanced transdermal penetration of carvedilol (CVD). For screening of nanoemulsion components, solubility of CVD in oils, surfactants and co-surfactants was determined. Various surfactants and co-surfactants were screened for their ability to nanoemulsify the selected oily phases. The obtained results indicated that Acconon CC6® had shown good nanoemulsification efficiency (minimum surfactant required S _min?=?46.52%?w/w) among the selected surfactants and further improved in presence of CO-20® (S _min?=?37.11%?w/w). The ranges of nanoemulsion existence were delineated through the construction of the pseudo-ternary phase diagram at different ratio of surfactant mixture (S/CoS), and various nanoemulsions were selected from phase diagram of S/CoS ratio 1?:?1. The effect of content of oil and S/CoS (1?:?1) on the skin permeation of CVD was evaluated through an excised wistar rat skin using Franz diffusion cell. All the nanoemulsions showed a high skin permeation rate (92.251–161.53?µg/cm²/h), good enhancement ratio (3.5–6.2) and high permeability coefficient in comparison to control groups. The optimised nanoemulsion formulation with the highest skin permeation rate (161.53?µg/cm²/h) consisted of 0.25%?w/w CVD, 12.5%?w/w Miglyol 810®, 50%?w/w Acconon CC6®/CO-20® (1?:?1) and water. The above formulation had the smallest mean globules size (9.28?nm). The superior transdermal flux of CVD may be due to nanorange size of oil globules that lead to intimate contact with the skin layer. These studies suggest that the nanoemulsion system is a promising vehicle for the transdermal delivery of CVD.     

Physicochemical Characterization of Rutaecarpine-Loaded Microemulsion System

To develop an o/w microemulsion system containing poorly water-soluble rutaecarpine, the solubility of rutaecarpine in water, ethanol, various oils, and surfactants were investigated. Among the surfactants and oils tested, Tween 20/PEG 400 and castor oil were chosen as the surfactant system and oil phase of the microemulsion, as rutaecarpine was most soluble in them, respectively. Pseudoternary phase diagrams were constructed to obtain the concentration range of oil, surfactant, and cosurfactant for microemulsion formation, and the stability test of rutaecarpine delivered by microemulsion formation was then evaluated. Pseudoternary phase diagrams show that the areas of microemulsion appeared at those with 0–20% Smix (PEG 400/Tween80 = 60/40), 64–81% water, and 10–20% oil. The rutaecarpine (300 µg/g)-loaded microemulsion composed of 10.8% PEG 400, 7.2% Tween 80, 20% caster oil, and 72% water was physically and chemically stable for at least 6 months. Thus, the microemulsion system composed of castor oil, PEG 400, Tween 80, and water could be a stable dosage form for rutaecarpine.     

Optimizing flurbiprofen-loaded NLC by central composite factorial design for ocular delivery

The purpose of this study was to design and optimize a new topical delivery system for ocular administration of flurbiprofen (FB), based on lipid nanoparticles. These particles, called nanostructured lipid carriers (NLC), were composed of a fatty acid (stearic acid (SA)) as the solid lipid and a mixture of Miglyol(?) 812 and castor oil (CO) as the liquid lipids, prepared by the hot high pressure homogenization method. After selecting the critical variables influencing the physicochemical characteristics of the NLC (the liquid lipid (i.e. oil) concentration with respect to the total lipid (cOil/L (wt%)), the surfactant and the flurbiprofen concentration, on particle size, polydispersity index and encapsulation efficiency), a three-factor five-level central rotatable composite design was employed to plan and perform the experiments. Morphological examination, crystallinity and stability studies were also performed to accomplish the optimization study. The results showed that increasing cOil/L (wt%) was followed by an enhanced tendency to produce smaller particles, but the liquid to solid lipid proportion should not exceed 30 wt% due to destabilization problems. Therefore, a 70:30 ratio of SA to oil (miglyol + CO) was selected to develop an optimal NLC formulation. The smaller particles obtained when increasing surfactant concentration led to the selection of 3.2 wt% of Tween(?) 80 (non-ionic surfactant). The positive effect of the increase in FB concentration on the encapsulation efficiency (EE) and its total solubilization in the lipid matrix led to the selection of 0.25 wt% of FB in the formulation. The optimal NLC showed an appropriate average size for ophthalmic administration (228.3 nm) with a narrow size distribution (0.156), negatively charged surface (-33.3 mV) and high EE (～90%). The in vitro experiments proved that sustained release FB was achieved using NLC as drug carriers. Optimal NLC formulation did not show toxicity on ocular tissues.     

RGO–MWCNT–ZnO based polypyrrole nanocomposite for ammonia gas sensing

Polypyrrole (PPy) nanocomposites were synthesized using ferric chloride (FeCl₃) as an oxidant by in situ polymerization at room temperature in which reduced graphene oxide- multi-walled carbon nanotubes (RGO–MWCNT) and zinc oxide (ZnO) were used as fillers. RGO–MWCNT and ZnO were synthesized by solution mixing and surfactant assistant precipitation respectively. The RGO–MWCNT–ZnO /PPy nanocomposites were prepared by loading 2, 5, 10 and 20 wt% of RGO–MWCNT:ZnO (1:1) in PPy to measure the electrical conductivity. The PPy nanocomposites were characterized by using FTIR, X-ray diffraction and FESEM. Furthermore, these RGO–MWCNT–ZnO/PPy nanocomposites were investigated to study sensing of ammonia gas at room temperature. The response of 20 wt% loading RGO–MWCNT–ZnO/PPy was observed to be 325% towards 200 ppm of ammonia gas.     

Effect of oil phase lipophilicity on in vitro drug release from o/w microemulsions with low surfactant content

In this work we investigated the effects of oil phase lipophilicity on in vitro drug release from topical o/w microemulsions (MEs) containing low percentages of emulsifiers. Three different lipids, isopropyl myristate (IPM), isopropyl palmitate (IPP), and isopropyl stearate (IPS), whose lipophilicity increased in the order IPM < IPP 相似文献   

Effect of Oil Phase Lipophilicity on In Vitro Drug Release from O/W Microemulsions with Low Surfactant Content

ABSTRACT

In this work we investigated the effects of oil phase lipophilicity on in vitro drug release from topical o/w microemulsions (MEs) containing low percentages of emulsifiers. Three different lipids, isopropyl myristate (IPM), isopropyl palmitate (IPP), and isopropyl stearate (IPS), whose lipophilicity increased in the order IPM < IPP <IPS, were used as oil phase to prepare o/w MEs containing low amounts (7.7% w/w) of two surfactant/cosurfactant mixtures, isoceteth-20/glyceryl oleate (5:2) (MEs 1–3) and oleth-20/glyceryl oleate (5:2) (MEs 4–6). All the MEs were prepared using the phase inversion temperature (PIT) method.

Three active compounds (0.5% w/w), Naproxen (NAP), Idebenone (IDE), and Butylmethoxydibenzoylmethane (BMBM), were selected as model drugs and their release rates from PIT MEs were evaluated using Franz-type diffusion cells. All the MEs gave a mean droplet diameter ranging from 28 to 44 nm and showed a single peak in size distribution. The addition of IDE to MEs 1–6 did not significantly change ME droplet size. On the contrary, an increase of the droplet size beyond the ME limit (150 nm) was observed when isoceteth-20 was used as surfactant to prepare MEs containing NAP or MEs containing BMBM and IPS as oil phase. Pseudo-first order release rates were observed only for NAP from MEs 1–3, while MEs containing IDE showed an initial slow release followed by an increased release of the test compound. The release rate constants were found to be dependent on the ME composition and on the active compound incorporated. The highest release rate was observed from ME 1 containing IPM as oil phase and NAP as drug. As regards BMBM, its release rate was not calculated since no release was observed until 6 h from the beginning of the experiment. The cumulative amount of active compound released after 22 h was inversely related to drug lipophilicity (NAP Log P = 2,9; IDE Log P 3,5; BMBM Log P 4,8). These findings could be attributable to a reduced thermodynamic activity of the drugs in the vehicles containing the most lipophilic oil phase due to an increase of drug solubility which could lead to an unfavorable drug partition from the oil phase. The results of this study suggest that the choice of proper combinations of oil phase lipids and emulsifiers may allow achieving drug controlled delivery from topical o/w MEs with low emulsifier content.     

Utilisation of oil-contaminated sand stabilised with cement kiln dust in the construction of rural roads

This article investigates the strength behaviour of oil-contaminated sand stabilised with cement kiln dust (CKD) in order to assess the engineering properties of the stabilised soil for its application in the construction of rural road. Tests including pH measurement, compaction, unconfined compressive strength (UCS) and California bearing ratio (CBR) were conducted. The investigations were carried out by varying the percentage of CKD, the percentage of oil content, the type of oil, the ageing of stabilised samples and the ambient temperature. Depending on the pH response, the CKD content from 5% to 15% represents a practical limit for cost-effective stabilisation. Results revealed that an increase in the UCS and CBR values of oil-contaminated sand occurred with the addition of CKD. The strength of stabilised contaminated sand decreases as the percentage of oil increases. The addition of 10% CKD to the sand contaminated with 6% oil content is found to give the optimum UCS and CBR values. Furthermore, a series of two-dimensional finite-element model was developed using PLAXIS software package.     

Design and development of a safer non-invasive transungual drug delivery system for topical treatment of onychomycosis

Objective: The main objective of this study is to develop a safer non-invasive treatment for nail infections since the current treatment regimen has drawbacks like, incidence of systemic side-effects and higher cost. Proposed topical treatment on the other hand can drastically improve the situation, hence highly desirable. This work was undertaken with a hypothesis to develop a transungual microemulsion gel for topical treatment of onychomycosis.

Methods: Benzyl alcohol and isopropyl myristate were used as oil, Pluronic F68 as surfactant and ethanol as co surfactant, in double-distilled water and loading itraconazole as the model antifungal drug. Pseudo-ternary phase diagram was developed by titrating different ratios of total oil and water with total surfactant, and K_m ratio was fixed at 1:1. Microemulsion formulations were prepared based on the phase diagram and incorporated in gels by adding Carbopol 934P. Nail permeation enhancers like urea and salicylic acid were used to increase drug permeation through the nail plate. Parameters like drug loading, clarity, particle size distribution, drug entrapment efficiency (DEE), drug release profile, release kinetics and nail uptake were checked for the evaluation of the formulations.

Results: Complete release of drug from the formulation varied from 60 to 120?min. The optimized formulation had DEE of 92.75%, complete drug release in 60?min and highest nail uptake of 0.386%/mm² (39?µg of drug) with 5% urea as nail permeation enhancer.

Conclusion: The formulation may prove beneficial in safer treatment of onychomycosis.     

Effects of temperature and soil components on emissions from pyrolysis of pyrene-contaminated soil

Effects of temperature and soil on yields and identities of light gases (H2, CH4, C2H2, C2H4, C2H6, CO, and CO2) and polycyclic aromatic hydrocarbons (PAH) from thermal treatment of a pyrene-contaminated (5 wt%) soil in the absence of oxygen were determined for a U.S. EPA synthetic soil matrix prepared to proxy U.S. Superfund soils. Shallow piles (140-170 mg) of contaminated soil particles and as controls, neat (non-contaminated) soil (140-160 mg), neat pyrene (10-15 mg), neat sand (230 mg), and pyrene-contaminated sand (160 mg), were heated in a ceramic boat inside a 1.65 cm i.d. pyrex tube at temperatures from 500 to 1100 degrees C under an axial flow of helium. Volatile products spent 0.2-0.4s at temperature before cooling. Light gases, PAH and a dichloromethane extract of the residue in the ceramic boat, were analyzed by gas chromatography or high pressure liquid chromatography (HPLC). Over 99% pyrene removal was observed when heating for a few tens of seconds in all investigated cases, i.e., at 500, 650, 750, 1000, and 1100 degrees C for soil, and 750 and 1000 degrees C for sand. However, each of these experiments gave significant yields (0.2-16 wt% of the initial pyrene) of other PAH, e.g., cyclopenta[cd]pyrene (CPP), which mutates bacterial cells and human cells in vitro. Heating pyrene-polluted soil gave pyrene conversions and yields of acetylene, CPP, and other PAH exceeding those predicted from similar, but separate heating of neat soil and neat pyrene. Up to 750 degrees C, recovered pyrene, other PAH, and light gases accounted for all or most of the initial pyrene whereas at 1000 and 1100 degrees C conversion to soot was significant. A kinetic analysis disentangled effects of soil-pyrene interactions and vapor phase pyrolysis of pyrene. Increase of residence time was found to be the main reason for the enhanced conversion of pyrene in the case of the presence of a solid soil or sand matrix. Light gas species released due to the thermal treatment, such as acetylene and methane, lead the formation of other, pyrene-derived PAH, e.g., methylpyrenes, cyclopenta[cd]pyrene, and benzo[a]pyrene. Implications of these findings for the chemistry of soil thermal decontamination and for diagnosing potential defects in soil thermal cleaning, e.g., incomplete elimination of targeted pollutants and formation of adverse by-products, are discussed.     

Development of industrially feasible concentrated 30% and 40% nanoemulsions for intravenous drug delivery

Emulsions for parenteral nutrition loaded with drugs are used for optimized drug delivery, but in case of poorly oil soluble drugs, the injection volume can be too large when using commercial 10–20% oil emulsions. To reduce the injection volume, the feasibility of producing injectable, physically stable concentrated emulsions up to 40% oil content was investigated. Emulsions were made from fish oil, stabilized with egg lecithin, using high-pressure homogenization. Emulsions with oil contents of 10%–40% were investigated to assess basic correlations between increasing oil content, applied production pressures, homogenization cycles and resulting bulk droplet size, content of larger particles, zeta potential, viscosity and short-term stability. The observed correlations showed that in high-pressure homogenization, the contribution of the dispersive effect dominated the coalescence effect at low and Optimum production conditions for 30% and 40% nanoemulsions, i.e. 800 bar and 2 -3 homogenization cycles, were established on lab scale. These production conditions are industrially feasible. The obtained droplet sizes (about 200?nm) and the content of larger droplets were comparable to 10% commercial emulsions of parenteral nutrition, being important for in vivo tolerability and organ distribution. Despite the high oil concentration, the viscosity of the nanoemulsions was sufficiently low for injection. The short-term storage study showed physical stability for 1 month. A concentrated nanoemulsion base formulation from regulatory accepted excipients is now available, ready for loading with drugs.     

Study on a new surfactant for removal of phenol from wastewater by emulsion liquid membrane

Removal of phenol from wastewater using emulsion liquid membrane (ELM) is studied in present study. A new polyamine-type surfactant was synthesized and used for stabilizing of the emulsion phase. The results for the emulsion made by the synthesized surfactant showed much better stability and performance in the separation process compared to that by conventionally used Span 80. To determine the optimum operation conditions, the effect of several parameters such as emulsifier concentration, concentration of NaOH in the internal phase, oil to internal phase volume ratio, mixing intensity, temperature, solvent type, and stabilizer concentration have been investigated. It was found that under the optimum conditions, more than 98% of phenol can be removed in a single-stage process. The removal efficiency can be increased to 99.8% in a two-stage process.     

Effect of the addition of oxybenzone or octyl-methoxycinnamate on particle size of submicron emulsions

The formulation of sunscreen products requires understanding of the solubilization of these products in different vehicles to obtain aesthetic preparations and to evaluate long-term stability. For this study, two different ultraviolet (UV) filters were selected: oxybenzone (powder) and octyl-methoxycinnamate (liquid). First, the solubility of these UV filters was tested using a three-component simplex-centroid design strategy. The mixtures were prepared with three oily phases used in this field of cosmetics: liquid paraffin, isopropyl myristate, and coconut oil. A phase diagram method was used to carry out a systematic study of submicron oil-in-water emulsions. Phase diagrams were produced by diluting fixed binary mixtures with water. The surfactant consisted of polyoxyethylene-20-sorbitan monostearate/sorbitan monostearate (50/50, w/w). The oily phase contained equal quantities of each oil studied. From this water/surfactant/oil ternary system, we selected two reference emulsions with receptively 75/5/20 and 68/7/25 proportions. Photon correlation spectroscopy (PCS) was used to investigate the influence of these two UV filters at several concentrations on droplet size and distribution of the oil droplets in the material. All emulsions were stored and checked every month for 6 months.     

Effect of the Addition of Oxybenzone or Octyl-Methoxycinnamate on Particle Size of Submicron Emulsions

The formulation of sunscreen products requires understanding of the solubilization of these products in different vehicles to obtain aesthetic preparations and to evaluate long-term stability. For this study, two different ultraviolet (UV) filters were selected: oxybenzone (powder) and octyl-methoxycinnamate (liquid). First, the solubility of these UV filters was tested using a three-component simplex-centroid design strategy. The mixtures were prepared with three oily phases used in this field of cosmetics: liquid paraffin, isopropyl myristate, and coconut oil. A phase diagram method was used to carry out a systematic study of submicron oil-in-water emulsions. Phase diagrams were produced by diluting fixed binary mixtures with water. The surfactant consisted of polyoxyethylene-20-sorbitan monostearate/sorbitan monostearate (50/50, w/w). The oily phase contained equal quantities of each oil studied. From this water/surfactant/oil ternary system, we selected two reference emulsions with receptively 75/5/20 and 68/7/25 proportions. Photon correlation spectroscopy (PCS) was used to investigate the influence of these two UV filters at several concentrations on droplet size and distribution of the oil droplets in the material. All emulsions were stored and checked every month for 6 months.