Hydrophilic-lipophilic Balance Values Research Articles

Optimization of HIB Value Combination of Tween 60 and Span 80 on Cream Formulation of Ethanol Extract of Green Tea Leaves (Camellia Sinensis L.)

Green tea (Camellia sinensis L.) is known to have ability to protect skin against free radicals. This is supported by polyphenol compound catechin. This research aims to determine the optimum Hydrophilic-Lipophilic Balance (HLB) value of Tween 60 and Span 80 compositions on the optimum cream formula of ethanol extract of green tea leaves. Tea leaves are extracted by macerating using 70% ethanol. Catechin in extract is known from Thin Layer Chromatography (TLC) test with silica gel 60 F254 as stationary phase and ethyl acetate:aquadest:formic acid (18:1:1 v/v) as mobile phase. Antioxidant activity is determined by 2,2-Diphenyl-1-picryhydrazyl (DPPH) method and value of Inhibition Concentration 50% (IC50) is then calculated. Formula optimization using Design Expert® version 7.1.5 (DX 7) software, Simplex Lattice Design (SLD) method with two components Tween 60 and Span 80. Cream is characterized according to physical properties organoleptic, homogeneity, viscosity, pH, spreadability, adhesiveness, and cream type. The optimum formula obtained is then tested for physical stability for 4 weeks at room temperature (28±2°C) and data are statistically analyzed using one-way ANOVA. The extract contains catechin proved with Retention factor (Rf) value 0.8 and has antioxidant activity with IC50 value 56.35 ppm. 6.4% Tween 60 and 3.6% Span 80 result an optimum HLB value 11.1. It has viscosity 2897.50±35.94 mPa.s, spreadability 18.44±0.06 cm2, adhesiveness 0.85±0.05 seconds, and pH 4.530±0.002. Statistical test shows that the cream is significantly altered at pH, but does not significantly change in viscosity, spreadability, and adhesiveness after being stored for 4 weeks.

Inter-Correlation among the Hydrophilic–Lipophilic Balance, Surfactant System, Viscosity, Particle Size, and Stability of Candelilla Wax-Based Dispersions

Owing to a decrease in mineral oil resources, it is crucial to develop packaging materials based on renewable resources. Hence, a water vapor-barrier coating is developed as a natural wax-based dispersion. This dispersion should be stable over the storage time. In this study, the physical stability of a wax-based melt dispersion was analyzed (24 h and 21 days after production), and instability phenomena such as agglomeration, coalescence, and flotation were identified. Furthermore, the inter-correlations among the particle size, viscosity of the continuous phase, physical stability, surfactant chemistry, and hydrophilic–lipophilic balance value were characterized. Particle sizes were described by volume/surface mean d3,2, volume moment mean d4,3, and number mean d1,0 diameter, as well as the span of the volume and number distribution. Stability was characterized by the flotation rate, emulsion stability index, and Turbiscan stability index. Coalescence and agglomeration were not observed after the solidification of the wax particles. A significant correlation was observed for the emulsion stability index, with d3,2, and for flotation rate, with d1,0, d4,3, and viscosity as well, with d1,0, d3,2. Surfactants with hydrophilic–lipophilic balance values of 11–13.5 seem to be the most suitable for stabilizing candelilla wax-in-water suspensions. Particles were smaller, and wax suspensions were better stabilized using Tween 20 and Span 20, compared with Tween 80 and Span 80.

Rapid Synthesis of Monodispersed TATB Microparticles in Ionic Liquid Micelles

ABSTRACTControlling microscopic morphology of energetic materials is of significant interest for the improvement of their performance and production consistency. As an important insensitive high explosive material, triaminotrinitrobenzene (TATB) has attracted tremendous research effort for military grade explosives and propellants. In this study, a new, rapid and inexpensive synthesis method for monodispersed TATB microparticles based on micelle-confined precipitation was developed. Surfactant with proper hydrophilic-lipophilic balance value was found to be critical to the success of this synthesis. The morphology of the TATB microparticles can be tuned between quasi-spherical and faceted by controlling the speed of recrystallization.

DESARROLLO DE DISPERSIONES DE OLEORRESINA DE PAPRIKA PARA MEJORAR LA BIOACCESIBILIDAD DE CAROTENOIDES

Red pepper (Capsicum annuum L.) oleoresin contain a diversity of carotenoids, which has been associated with lower risk for different chronic diseases like various types of cancer, cardiovascular disease and age-related macular degeneration. However, they are very sensitive to pro-oxidant conditions, heat and light. Previous attempts have been made to improve bioavailability and stability of carotenoids, of which emulsions have proven to help a feasible method. Conventional (CE) and nano (NE) emulsions loaded with paprika oleoresin carotenoids (POC; 1 % wt/wt) were fabricated using surfactants blend (Tween 40 and Span 20) with a hydrophilic-lipophilic balance (HLB), ranging from 12 to 15.6, and surfactant: POC ratio of 1:1 (wt/wt). POC bioaccessibility was studied using an in vitro model to simulate oral, gastric and small intestine phases of the gastrointestinal tract (GIT). In general, higher HLB values produced CE's and NE's with smaller particle size and negative value of zeta potential. The smaller the droplet size, the higher was POC bioaccessibility. NE prepared with a HLB of 15.6 had a particle size of 38.93 nm and a bioaccessibility of 74%. Bioaccessibility of unemulsified POC was practically nil. Conventional and nanoemulsions protected paprika oleoresin carotenoids deterioration during simulated gastrointestinal tract.

Polymeric surfactants with tricyclic rigidity from natural rosin: Synthesis and dispersion of single-walled carbon nanotubes in aqueous solution

Polymeric surfactants from natural rosin containing a unique tricyclic rigid structure were prepared and their structures were characterized by IR, 1H NMR and GPC. Their surface activities including hydrophile—lipophile balance values (HLB), emulsification properties, foaming properties, critical micelle concentration (CMC) and the minimum surface tension (γCMC) were evaluated. With the increase in ratio of hydrophobic to hydrophilic in polymeric surfactant, the CMC values of the surfactants decreased, and the emulsification and foaming properties of these surfactants increased, and the HLB values of them decreased. This type of polymeric surfactants was used to disperse single-walled carbon nanotubes (SWCNTs) in water, and their dispersal capacities were comparatively determined by UV-visible absorption spectroscopy. Thermogravimetric analysis (TGA) was used to quantify the amount of surfactant attached onto the nanotubes. More intuitive image of their dispersion states were obtained by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The results showed that this type of polymeric surfactants had good dispersion capacity and dispersion stability to SWCNTs in water through strong hydrophobic attraction and weak van der Waals interactions.

Lightweight structural eco-mortars made with polyurethane wastes and non-Ionic surfactants

The properties of structural lightweight mortars obtained with recovered foam polyurethane wastes have been studied, containing a low fraction of soluble non-ionic surfactant. The characterisation of mechanical properties, bulk density, microstructure and porosity highlights two types of behaviour according to the composition (e.g. hydrolysis grade) of the non-ionic surfactants. By using additives with low hydrophilic–lipophilic balance (HLB) values, the lightweight mortars show more and more high mechanical properties according to the increase of the substitution rate of sand by PU wastes. These non-ionic surfactants seem to promote a homogeneous microstructure and improve the adhesion between PU wastes and cement paste. On the other hand, the mortars mixed with additives showing high HLB values, are more lightweight and macroporous, due to the increase of air entrained driven by the substitution rate of sand by PU wastes.

Enhanced stability of bio-oil and diesel fuel emulsion using Span 80 and Tween 60 emulsifiers

Bio-oil (biomass pyrolysis oil) has some undesirable properties (e.g., low heating value, high corrosiveness, and high viscosity) that restrain its direct use as a transportation fuel. The emulsification of bio-oil and diesel is an effective and convenient method to use bio-oil in the present transportation fuel infrastructure. The addition of an emulsifying agent (emulsifier or surfactant) to two immiscible liquids of diesel and bio-oil is an important step in emulsification. The hydrophilic–lipophilic balance (HLB) value, according to the chemical structure and characteristics of the emulsifier, is a key parameter for selecting a surfactant. In this study, an ether treatment of raw bio-oil was carried out to separate the ether-soluble fraction of bio-oil from its heavy (dark brown and highly viscous) fraction, and the ether-extracted bio-oil (EEO) was processed further for emulsification into diesel fuel. The effects of the HLB value of the emulsifier and the contents of EEO, diesel, and emulsifier on the stability of the EEO/diesel emulsion were investigated. To optimize the HLB value of the emulsifier, different HLB values (4.3–8.8), which were prepared by mixing different amounts of Span 80 and Tween 60 as surfactants, were used for the EEO and diesel emulsification. A HLB value of 7.3 with diesel, EEO, and emulsifier contents of 90, 5, 5 wt%, and 86, 7.4, 6.6 wt% resulted in EEO/diesel emulsions (without phase separation) stable for 40 and 35 days, respectively. Measurement of the high heating value (HHV) of the emulsified fuels gave a 44.32 and 43.68 MJ/kg values for the EEO to emulsifier mass ratios of 5:5 and 7.4:6.6, respectively. The stability of emulsified EEO and diesel was verified by TGA and FT-IR methods.

Challenge sodium lignosulfonate surfactants synthesized from bagasse as an injection fluid based on hydrophil liphophilic balance

The aim of this research is to obtain Sodium Lignosulfonate (SLS) surfactant from bagasse as an alternative petroleum sulfonate. The experimental method of the process SLS surfactant from bagasse through two processes, hydrolysis and sulphonation process. Then tested for its characteristics through FTIR test, LCMS test, NMR test and compatibility test. Based on the structure of the sodium lignosulfonate of bagasse with the empirical formula of lignosulfonate monomer is (C11H16O8S)n, have hydrophil and lipophyl groups. The calculation of Hydrophilic Lipophilic Balance (HLB), the synthesized SLS surfactant of bagasse has a HLB value of 11.62. From the compatibility test, this SLS surfactant have a good aquaeous stability, no turbidity, perfect soluble and clear. This SLS surfactant capable of water wet system and having the category as an O/W (Oil in Water) emulsion, indicating that the surfactant good dissolves in water. The mechanism of the synthesized SLS surfactant of the bagasse produces a good microemulsion between surfactant and oil. HLB is one of the parameters used to determine surfactant function. Based on the characteristic test and HLB value calculation it turns out that bagasse can be used as SLS surfactant. As an injection fluid in the EOR process, the SLS surfactant from bagasse has been in the function as O/W emulsion. So the use of lignosulfonate surfactant synthesized from bagasse is a challenge to be developed futher as a surfactant for the EOR process.

Nanoemulsification of Satureja khuzestanica essential oil and pure carvacrol; comparison of physicochemical properties and antimicrobial activity against food pathogens

The aim of the present study was to fabricate a stable carvacrol-rich Satureja khuzestanica essential oil (SKEO) nanoemulsion and evaluate its antibacterial activity against food borne pathogens. The effect of determining factors including preparation method, surfactant type, surfactant to oil ratio and hydrophilic lipophilic balance (HLB) were evaluated on the mean particle size and stability of nanoemulsions. The optimized formulation prepared by high speed homogenization method containing 3%w/w EO and 9%w/w surfactant mixture (Tween 80 + Span 80) with HLB value of 10 that produced stable nanoemulsion with mean particle diameter of 95 nm. The defined conditions were applied for fabrication of pure carvacrol nanoemulsion. Both formulations showed appreciable long-term stability. The antibacterial activity of pure SKEO, carvacrol and their nanoemulsions were examined against three food-borne bacteria. The results showed an improvement in antibacterial activity for carvacrol and SKEO nanoemulsions against Salmonella enterica and Staphylococcus aureus.

Experimental investigation of coal dust wetting ability of anionic surfactants with different structures

Abstract To better understand the coal dust wetting ability of anionic surfactants with different structures, sodium dodecyl sulfate (SDS), sodium dodecyl sulfonate (SDDS), and sodium dodecyl benzene sulfonate (SDBS) were selected. The surface tension, wetting time, and infrared spectra of coal dust were tested. The hydrophilic-lipophilic balance (HLB) values of the surfactants were calculated. Results showed that the decrease in the surface tension could shorten the wetting time at low surfactant concentrations. But the decrease in the wetting time was no longer related to the constant surface tension that was lower than 45 mN/m. The adsorption density depends on the hydrophobic interactions and electrostatic repulsions between the surfactant molecules and the coal dust. During the dynamic immersion process, the surfactants with high HLB values could bring the coal dust into the bulk solution rapidly. The wetting time of coal dust for SDBS with a high adsorption density and low HLB or SDS with a small adsorption density and high HLB was relatively longer. The adsorption density and HLB value of SDDS were intermediate between those of SDS and SDBS. Under the combined action of these two factors, the wetting time of SDDS was shorter than those of SDS and SDBS.

Studying the lubricity of new eco-friendly cutting oil formulation in metal working fluid

PurposeThis paper aims to formulate a new metal working fluid (MWF) composition including some eco-friendly emulsifiers, corrosion inhibitor, biocide, and non- edible vegetable oil (castor oil) as the base oil. To achieve this aim, five MWFs with different hydrophilic–lipophilic balance (HLB) value as 10, 9.5, 9, 8.5 and 8 were prepared to identify the optimum HLB value that gives a highly stable oil-in-water emulsion. The performance of castor oil based MWF was evaluated using tool chip tribometer and drill dynamometer. The surface morphology of steel disc and friction pin was performed using scanning electron microscope (SEM) and 3D profilometer. The results revealed that the use of the prepared cutting fluid (E1) caused the cutting force to decrease from 500 N for dry high-speed steel sample to 280N, while the same value for a commercial cutting fluid (COM) was recorded as 340 N at drilling speed and cutting feed force as 1120 rpm and 4 mm/min., respectively.Design/methodology/approachA castor oil-based metalworking fluid was prepared using nonionic surfactants. The composition of the metalworking fluid was further optimized by adding performance-enhancing additives. The performance of castor oil based MWF was analyzed using Tool chip tribometer and Drill dynamometer. The surface morphology of steel ball and a disc was done using 3D profilometer and SEM.FindingsStudies revealed that castor oil-based MWF having Monoethanolamine (MEA) as corrosion inhibitor was found to be highly stable. The drilling dynamometer and tool chip tribometer studies showed that castor oil-based MWF performance was comparable to that of commercial MWF.Research limitations/implicationsThis study aims to explore the performance of the castor oil based metalworking fluid (MWF) using tool chip tribometer and drill dynamometer.Practical implicationsThe conventional MWFs are petroleum derives and are unsustainable. Use of non-edible plant-based oils for preparing the MWF will not only be conserved environment but also add value addition to agricultural crops.Social implicationsThe social Implications is aiming to decrease the environmental impact that results from the using of mineral cutting fluids.Originality/valueThe originality of this work is to replace the mineral oil and synthetic oil based cutting fluids with more eco-friendly alternatives one. In addition, the investigation will focus on developing functional additives required for cutting fluids which are environmentally benign.

Preparation of an environmentally friendly emulsion-type lubricant based on crude rice bran wax

Abstract In this study, crude rice bran wax oil - in - water emulsion (named CRBWE) was prepared by agent-in-water method. The critical factors influencing the sample preparation process were optimized. For instance, the optimum hydrophile-lipophile balance value of compound emulsifier was 12.33–13.40, the content of compound emulsifier was 10 wt%, the emulsification temperature was 70 °C–80 °C, the agitation speed was 200 rpm, and the emulsification time was 30–45 min. The performances as a lubricant of drilling fluid were also evaluated with respect to lubricity, rheology and filtration loss of CRBWE. The results showed that CRBWE had good lubricity and didn't affect the rheological properties of drilling fluid. For example, when it was added into bentonite dispersion at room temperature with the fraction of 1 wt%, the coefficient of friction of bentonite dispersion dramatically decreased to 0.077, and the coefficient of friction reduced rate was greater than 80%. Overall, these findings indicated that CRBWE would have promising applications as environmental friendly lubricant of drilling fluids to reduce torque and drag in petroleum and natural gas drilling.

Noval tannic acid-based polyether as an effective demulsifier for water-in-aging crude oil emulsions

The water-in-aging crude oil (WACO) emulsions treatment is an urgent problem in the offshore platform because of the low demulsification efficiency of conventional demulsifier. To resolve this problem, a new kind of tannic acid phenol-amine (TAPA) polyether with multiple branches, and aromatic rings is prepared in this article. This synthetic route is expected to avoid the side reactions during the synthesis of commercial phenol-amine resin. Benefit from this structure, the demulsification efficiency reaches 91.7% within 90 min in laboratory test and 97.9% within 45 min on offshore platform measurement toward WACO emulsions. Demulsification mechanism is systematically investigated by the measurements of hydrophile-lipophile balance (HLB) value, relative solubility number (RSN) value, dosage, interfacial activity and stability analysis. To have a direct insight into demulsification, the variation of water droplets in demulsification is observed. The effect of concentration and organic salts on cloud point are discussed. The demulsification effectiveness of TAPA demulsifier is mainly ascribed to the high interfacial activity, hyperbranched structure, multiple aromatic rings and suitable HLB value. These results indicate that TAPA could be an effective demulsifier in WACO emulsions breaking.

Encapsulation of Mangosteen Extract in Virgin Coconut Oil Based Nanoemulsions: Preparation and Characterization for Topical Formulation

Nanoemulsions containing extract of mangosteen (Garcinia mangostana L.) rind has been developed and characterized as a topical formulation. The encapsulation of mangosteen extract in nanoemulsions is considered a promising strategy to utilize the available bioactive compounds, particularly α-mangostin. In this study, a high-speed homogenization method was used to produce nanoemulsions of virgin coconut oil as the oil phase, combined Tween 80 and Span 80 as the oil-in-water surfactant, and distilled water as the aqueous phase. The homogenizer speed, oil and surfactant composition, and, hydrophilic lipophilic balance values of the surfactants were varied in order to get stable nanoemulsions formulation. The most stable nanoemulsion was obtained using a homogenizer speed of 8000 rpm, oil to surfactant volume ratio of 1:1.4, and surfactant hydrophilic lipophilic balance value of 12. Nanoemulsion formulation with average droplet size of 181 nm, zeta potential of -30.9 mV, and 0.01% α-mangostin loading was stable for 28 days without phase separation. Based on the accelerated stability test, the nanoemulsion shelf life is estimated to reach one year. The present study revealed that the virgin coconut oil-based nanoemulsion is a promising carrier of mangosteen extract for topical formulation.

One-Pot Synthesis of Biomass-Derived Surfactants by Reacting Hydroxymethylfurfural, Glycerol, and Fatty Alcohols on Solid Acid Catalysts.

A new type of biomass-derived non-ionic surfactants has been obtained by reacting hydroxymethylfurfural (HMF), glycerol, and fatty alcohols. For instance, 5-(octyloxymethyl)furfural glyceryl acetal can be obtained in a one-pot process by etherification of HMF with fatty alcohols followed by acetalization with glycerol. For a successful solid catalyst, acidity and polarity have to be optimized to improve conversion, selectivity, and catalyst deactivation owing to the different adsorption characteristics of the reactant molecules. Accordingly, Beta zeolite with a high Si/Al ratio and practically free of connectivity defects showed good results when dealing with these biomass derivatives, which include a highly polar reactant such as glycerol. The scope of the reaction is good and a variety of new stable surfactant molecules can be obtained that present hydrophilic-lipophilic balance (HLB ) values in the range 4.9 to 6.6, which are of interest for water in oil emulsions.

Design of biosystems to provide healthy and safe food. Part A: effect of emulsifier and preparation technique on physicochemical, antioxidant and antimicrobial properties

In this study, the effect of emulsifier and preparation technique on physicochemical properties and antioxidant/antimicrobial activity of plant oil (lemongrass and oregano, 1:1)/citrus extracts incorporated in oil-in-water (O/W) microemulsion in comparison to coarse emulsion, was investigated. The optimization of O/W microemulsion was performed by two surfactants with different hydrophilic–lipophilic balance values and two techniques of preparation such as sonication and microfluidization. The stability of microemulsions during storage time regarding to the droplet size, ζ-potential, viscosity, total polyphenolics content, total flavonoids content, antioxidant, antiradical and antimicrobial activity were assessed. Micro-emulsification increased the bioactivity of plant oil/citrus extracts by increasing the surface area of droplets induced by size decrement. Microfluidized and sonicated emulsions showed the same relatively stable profile during storage time. Micro-emulsification improves the functionality of plant oil/citrus extracts, such as antioxidant and antiradical activity. An increment about 16–32 times in antimicrobial activity of plant oil/citrus extracts was also attained. Furthermore, the morphology of microemulsions observed by transmission electron microscopy, confirmed a mono-dispersed nano-sized emulsion.

Mitigation of NOx and smoke emissions in a diesel engine using novel emulsified lemon peel oil biofuel

Lemon peel oil (LPO) is considered to be a viable alternative fuel for diesel engine applications due to its wider availability, renewable nature, easy extraction process, almost equivalent calorific value as neat diesel, and low viscosity. The present work aims to investigate the effect of novel emulsified LPO in a diesel engine in order to reduce the NOx emission without compromising the engine performance. A new ionic surfactant is introduced in the present study, namely methyl-dihydroxy propyl imidazolium chloride due to its higher hydrophilic-lipophilic balance value which helps to prepare stable water in oil emulsion. Also, Span 80 has been selected as another suitable surfactant for water in oil emulsion. Four emulsified fuel samples have been prepared using LPO, water, and different concentrations of surfactants. All the fuel samples are tested for their stability through gravitational technique for 7days. Among the emulsified samples, 92% LPO + 5% water + 2% Span 80 + 1% methyl-dihydroxy propyl imidazolium chloride by volume (LPOE2) and 93.5% LPO + 5% water + 1.5% surfactant Span 80 by volume (LPOE4) have showed better stability when compared to other emulsion fuel samples. It is also revealed that the stability of LPO emulsion is improved by the addition of two emulsions. The experimental results showed that the brake thermal efficiency of LPO emulsion is reduced to 29.87 from 34.58% of pure LPO at full load condition. Oxides of nitrogen emission and smoke emission are reduced by 21-32 and 6-15% for the LPO emulsion samples compared to pure LPO. Moreover, the diesel engine operation with emulsified form of LPO increases the HC emission about 0.1g/kWh for LPOE4 and 0.15g/kWh for LPOE2 fuels from 0.053g/kW for pure LPO at maximum power output condition. The reformulation of LPO into emulsified form increases the CO emission by 25-53% compared to pure LPO. Moreover, the reformulation of LPO into emulsions has resulted in lower cylinder pressure and heat release rate compared to pure LPO and diesel fuels.

The influence of monobutyl itaconate and β-carboxyethyl acrylate on acrylic latex pressure sensitive adhesives

The application of two different kinds of carboxylic monomers, monobutyl itaconate (MBI) and β-carboxyethyl acrylate (β-CEA), in acrylic pressure sensitive adhesive (PSA) latexes is presented in this article. The hydrophilic-lipophilic balance (HLB) values of carboxylic monomers were calculated to determine their water solubility, which was further confirmed by their partition coefficients between organic and water phases. Influences of the functional monomers on particle size and zeta potential of the latexes, as well as on water resistance, thermal stability, gel content, sol molecular weight (Mw, Mn) and adhesive properties of the polymer were investigated in this work. In addition, the application of commonly used methacrylic acid (MAA) was also determined as a benchmark. The results indicated that for equiweight amounts of acid comonomer, latex particle sizes fall in the order: MBI > MAA > β-CEA, depending on water solubility of the corresponding monomer. Besides, the latex film prepared with MBI showed the best water resistance when compared with other two counterparts. Results also indicated that the PSA prepared with β-CEA exhibited the highest gel content among the three acid monomers. Moreover, the thermal stability of the three carboxylated polymers follow the order P(n-BA+MAA) > P(n-BA+β-CEA) > P(n-BA+MBI). Finally, the effects of carboxylic monomers on the adhesive properties of the PSAs were also evaluated.

Formulation of oil-in-water emulsions for pesticide applications: impact of surfactant type and concentration on physical stability.

Oil-in-water (O/W) emulsions can be utilized as effective pesticide delivery systems in the agricultural industry. In this study, the effects of hydrophile-lipophile balance (HLB), concentration, and location of surfactants on the formation and physical stability of O/W emulsions suitable for pesticide applications was investigated using dynamic light scattering and vertical laser profiling. A non-polar pesticide (lambda-cyhalothrin) was used as a model. The pesticide emulsion with the highest stability was obtained using a commercial non-ionic surfactant (polyoxyethylene castor oil ether, EL-20) with a required HLB value of 10.5. Emulsion stability increased as the surfactant concentration was increased from 2 to 6%, which was attributed to the formation of smaller oil droplets during emulsification. Emulsions prepared with the surfactant initially in the oil phase were more stable than those prepared with it initially in the aqueous phase. The optimum formulation of the pesticide emulsion was determined as follows: 5% lambda-cyhalothrin (active ingredient) and 6% EL-20 (surfactant) dissolved in 5% S-200 (aromatic hydrocarbon, as oil phase), then deionized water up to 100%, which met the quality indicators set by the FAO standards. The present study is expected to provide useful information to improve the stability of pesticide emulsions for commercial applications.

Microemulsions as Platforms for Transdermal Delivery of Hydrophilic Drugs - A Review

Background: Delivery rates in cutaneous applications are limited by the skin barrier and also by the physical-chemical properties of the drug in the formulation. A lipophilic drug has more affinity, and can permeate the epidermis more easily than a hydrophilic drug. The potential use of nano-sized dispersions as distribution systems for hydrophilic drugs is being investigated. Objective: To analyze the literature with regard to the development of microemulsions (ME) for transdermal delivery of hydrophilic drugs, with a view to identifying strategies to increase the permeation of these drugs. Results: One hundred and eleven articles were potentially relevant to the combination of search criteria. After excluding duplicated articles, the abstracts of 83 articles were read. Of these, 73 did not meet the inclusion criteria. To complete the review process, the whole text of 10 articles was evaluated. Conclusion: The main factors that positively influenced the permeation of hydrophilic drugs were low hydrophilic-lipophilic balance (HLB) values of the surfactant; concentrations of about 40% of surfactants and 30% of aqueous phase for the water-in-oil (W/O) systems; the addition of permeation promoters to the systems; and the association of physical methods during the application of the ME. The results offered support for the development of new topical microemulsions for hydrophilic drug delivery.