Plasma Permeabilization of Human Excised Full-Thickness Skin by µs- and ns-pulsed DBD.

INTRODUCTION: Cold atmospheric plasma (CAP) is gaining increasing importance as a medical or cosmetic treatment for various indications. The technology is best suited to the treatment of surfaces such as the skin and is already used in wound care and, in exemplary case studies, the reduction of superficial tumors. Several plasma sources have been reported to affect the skin barrier function and potentially enable drug delivery across or into plasma-treated skin. OBJECTIVE: In this study, this effect was quantified for different plasma sources in order to elucidate the influence of voltage rise time, pulse duration, and power density in treatments of full-thickness skin. METHODS: We compared three different dielectric barrier discharges (DBDs) as to their permeabilization efficiency using Franz diffusion cell permeation experiments and measurements of the transepithelial electrical resistance (TEER) with full-thickness human excised skin. RESULTS: We found a significant reduction of the TEER for all three plasma sources. Permeation of the hydrophilic sodium fluorescein molecule was enhanced by a factor of 11.7 (low power) to 41.6 (high power) through µs-pulsed DBD-treated skin. A smaller effect was observed after treatment with the ns-pulsed DBD. CONCLUSIONS: The direct treatment of excised human full-thickness skin with CAP, specifically a DBD, can lead to pore formation and enhances transdermal transport of sodium fluorescein.

The Petroleum Ether Extract from Hypericum perforatum Root Cultures Exhibits Potent Antiproliferative Activity in Human Keratinocytes and Fibroblasts.

The hyperforin content of Hypericum perforatum herb was repeatedly reported to be responsible for a multitude of pharmacological activities. Our recent report about the hyperforin accumulation in in vitro root cultures of H. perforatum provides an alternative perspective to achieve constant product quality and to serve the rapidly growing market. In this study, the antiproliferative effect of a petroleum ether extract from the in vitro root cultures was investigated. When normalized to 1 µM hyperforin content, the extract reduced the viability of human keratinocytes (HaCaT) and human dermal fibroblast monolayers to 33 and 36%, respectively, after 72 h of incubation. A cytotoxicity assay and live-dead cell staining confirmed that the extract lacked a cytotoxic effect and that the reduction in cell viability was mainly due to the antiproliferative activity. Application of the 1 µM hyperforin-normalized extract to a 3D artificial skin construct significantly reduced the proliferation of HaCaT in the presence of fibroblasts. This effect was proved by the reduction in thickness of the epidermal construct from 100 µm (control) to 17 µm (treated). Notably, 1 µM pure hyperforin lacked effectiveness in both monolayer cultures and 3D artificial skin constructs. Nor were fractions of the extract containing colupulone and xanthones active. The combination of these constituents also failed to reassemble the antiproliferative activity, which indicates a synergistic role of yet unidentified components present in the extract. Our findings may introduce H. perforatum root cultures as a novel lead system for the treatment of hypertrophic scars.

Novel Colloidal Microstructures of ß-Escin and the Liposomal Components Cholesterol and DPPC.

The discovery of immunostimulating complex formation by the saponin Quil A from the plant Quillaja saponaria with cholesterol and a phospholipid opened up new avenues for the development of drug delivery systems for vaccine application with additional adjuvant properties. In this study, ß-escin, a monodesmosidic triterpene saponin from horse chestnut, was investigated in terms of its interaction with liposomal components (cholesterol, dipalmitoylphosphatidylcholine) by Langmuir film balance studies and with regard to particle formation visualized by transmission electron microscopy. A strong interaction of ß-escin with cholesterol was observed by Langmuir isotherms due to the intercalation of the saponin into the monolayer, whereas no interaction occurred with dipalmitoylphosphatidylcholine. Transmission electron microscopy studies also confirmed the strong interaction of ß-escin with cholesterol. In aqueous pseudo-ternary systems (ß-escin, dipalmitoylphosphatidylcholine, cholesterol) and in pseudo-binary systems (ß-escin, cholesterol), new colloidal structures built up from ring-like and worm-like subunits were observed with a size of about 100 - 200 nm. These colloidal structures are formed in pseudo-binary systems by aggregation of the subunits, whereas in pseudo-ternary systems, they are formed among others by attacking the liposomal membrane. The rehydration of the liposomal dispersions in NANOpure water or Tris buffer pH 7.4 (140 mM) resulted in the same particle formation. In contrast, the sequence of the dispersions' production process affected the particle formation. Unless adding the saponin to the other components from the beginning, just a liposomal dispersion was formed without any colloidal aggregates of the subunits mentioned above.

The effect of miscellaneous oral dosage forms on the environmental pollution of sulfonamides in pig holdings.

BACKGROUND: Due to antibiotic treatment of humans and animals, the prevalence of bacterial resistances increases worldwide. Especially in livestock farming, large quantities of faeces contaminated with antibiotics pose a risk of the carryover of the active ingredient to the environment. Accordingly, the aim of the present study was the evaluation of the benefit of different oral dosage forms (powder, pellets, granula) in pigs concerning the environmental pollution of sulfadiazine. Two subtherapeutic dosages were evaluated in powder mixtures to gain information about their potential to pollute the pig barn. Furthermore, a new group of pigs was kept in the stable after powder feeding of another pig group to determine the possible absorption of environmentally distributed antibiotics. Pigs were orally treated with three dosage forms. Simultaneously, sedimentation and airborne dust were collected and plasma and urine levels were determined. RESULTS: All formulations result in comparable plasma and urine levels, but massive differences in environmental pollution (powder > pellets, granula). Pigs housing in a contaminated barn exhibit traces of sulfadiazine in plasma and urine. CONCLUSION: Using pharmaceutical formulations like pellets or granula, the environmental pollution of sulfonamides can significantly be diminished due to massive dust reduction during feeding.

Saponin Interactions with Model Membrane Systems - Langmuir Monolayer Studies, Hemolysis and Formation of ISCOMs.

Saponins are used in medicine due to their pharmacological and immunological effects. To better understand interactions of saponins with model membranes and natural membranes of, for example, erythrocytes, Langmuir film balance experiments are well established. For most saponins, a strong interaction with cholesterol was demonstrated in dependence of both the aglycone part and the sugar moieties and is suggested to be correlated with a strong hemolytic activity, high toxicity, and high surface activity, as was demonstrated for the steroid saponin digitonin. In general, changes in the sugar chain or in substituents of the aglycone result in a modification of the saponin properties. A promising saponin with regard to fairly low hemolytic activity and high adjuvant effect is α-tomatine, which still shows a high affinity for cholesterol. An interaction with cholesterol and lipids has also been proven for the Quillaja saponin from the bark of Quillaja saponaria Molina. This triterpene saponin was approved in marketed vaccines as an adjuvant due to the formation of immunostimulating complexes. Immunostimulating complexes consist of a Quillaja saponin, cholesterol, phospholipids, and a corresponding antigen. Recently, another saponin from Quillaja brasiliensis was successfully tested in immunostimulating complexes, too. Based on the results of interaction studies, the formation of drug delivery systems such as immunostimulating complexes or similar self-assembled colloids is postulated for a variety of saponins.

Cytotoxic effect and mechanism inducing cell death of α-mangostin liposomes in various human carcinoma and normal cells.

The aims of this study were to develop α-mangostin liposomes as well as to evaluate their physicochemical properties and cytotoxic activity. α-Mangostin liposomes were prepared using the reverse-phase evaporation method with lipid composition of phosphatidylcholine to cholesterol at 7 : 3 molar ratios; their physicochemical properties and antiproliferative activity were assessed using an MTT assay in four human carcinoma cells [that is, human lung epithelial carcinoma (Calu-3), human colon carcinoma (HT-29), human breast carcinoma (MCF-7), and human colon carcinoma (Caco-2) cells], and two human normal cells [that is, human dermal fibroblasts (HDF) and human adult low-calcium elevated temperature (HaCaT) keratinocytes]. Determinations of morphological changes and oligonucleosomal DNA fragments were also carried out. The liposomal dispersions obtained were unilamellar vesicles as confirmed by cryotransmission and freeze-fracture electron microscopy with a particle size of 114 nm and a ζ potential of -2.56 mV. The P-NMR spectra showed that α-mangostin molecules orientated in the phospholipid bilayer membrane. The α-mangostin could appreciably be entrapped with an efficiency and loading of 81 and 4%, respectively. The antiproliferative activity of α-mangostin liposomes in various cancer and normal cells showed a dose-dependent inhibition in all treated cell lines. The antiproliferative effect of α-mangostin liposomes was found to be associated with apoptosis, with differences in sensitivity among the cell lines treated.

Comparison of the antifungal efficacy of terbinafine hydrochloride and ciclopirox olamine containing formulations against the dermatophyte Trichophyton rubrum in an infected nail plate model.

Onychomycosis is a fungal infection mostly induced by dermatophytes such as Trichophyton rubrum. Due to slow nail growth, the treatment takes 3-9 months depending on the nail size and infected area. Hence, high efficacy of the active ingredient without systemic side effects is of major interest. To test the efficacy of an antifungal formulation, an appropriate in vitro model reflecting the in vivo situation as close as possible is required. In this study, a variety of antifungal formulations, i.e., commercial ones (Ciclopoli and Lamisil cream), those used in compounding pharmacies (Pentravan) as well as poloxamer 407-based systems, have been evaluated in an infected nail plate model. The active pharmaceutical ingredients (APIs) were ciclopirox olamine and terbinafine hydrochloride. The poloxamer 407-based formulations consisted of poloxamer 407, double distilled water, propylene glycol, isopropyl alcohol, medium chain triglycerides and either 1% ciclopirox olamine or 1% terbinafine hydrochloride as API, respectively. Former studies have shown high permeation rates of terbinafine hydrochloride from similar poloxamer 407-based formulations with dimethyl isosorbide instead of propylene glycol. The present contribution shows superior inhibition of T. rubrum growth from poloxamer 407-based formulations in comparison to the commercial Lamisil cream. Moreover, poloxamer 407-based formulations were equally effective as the nail lacquer Ciclopoli even though the poloxamer formulations contained only 1% of the drug instead of 8% in the marketed lacquer. Poloxamer 407-based systems containing ciclopirox olamine proved to be about as effective as similar terbinafine hydrochloride systems.

Development of a prospective isopropyl alcohol-loaded pharmaceutical base using simultaneous in vitro/in vivo characterization methods of skin performance.

CONTEXT: Approaching of pharmaceutical and cosmetic industries in some aspects inevitably influence formulation of topical pharmaceuticals, urging researchers to introduce novel excipients with proven benefits over traditional ones. In that context, alkyl polyglucosides (APG) emerge as prominent natural-origin emulsifiers with numerous favorable features (biodegradability, dermatological acceptability, desirable sensory properties). OBJECTIVE: To evaluate APG-stabilized bases (alone and upon addition of isopropyl alcohol) and their impact on skin performance. A simultaneous in vitro/in vivo skin absorption study was conducted to evaluate whether the tape stripping technique could be recommended as an in vivo tool for skin penetration assessment during formulation optimization process. MATERIALS AND METHODS: After a comprehensive physicochemical characterization, biopharmaceutical properties of APG-bases versus reference ones were assessed through a combined in vitro (release/permeation) and in vivo approach. RESULTS AND DISCUSSION: Physicochemical characterization revealed substantial difference in structural ordering due to the formation of various mesomorphic phases. The enhancer-loaded APG base resulted in significantly higher drug levels at all depths into the stratum corneum, indicating that the selected enhancer along with specific colloidal structure has increased the extent of drug delivery. CONCLUSION: Results recommend the investigated emulsifier for stabilization of topical drug delivery systems, not only for their ability to sustain the addition of isopropyl alcohol which proved to be a valuable enhancer, but also satisfactory skin absorption and tolerability when compared to samples stabilized by conventional emulsifier. Tape stripping proved to be a useful and yet inexpensive tool for in vivo trials, able to discriminate subtle differences in dermal availability.

Nanoparticle-mediated pulmonary drug delivery: a review.

Colloidal drug delivery systems have been extensively investigated as drug carriers for the application of different drugs via different routes of administration. Systems, such as solid lipid nanoparticles, polymeric nanoparticles and liposomes, have been investigated for a long time for the treatment of various lung diseases. The pulmonary route, owing to a noninvasive method of drug administration, for both local and systemic delivery of an active pharmaceutical ingredient (API) forms an ideal environment for APIs acting on pulmonary diseases and disorders. Additionally, this route offers many advantages, such as a high surface area with rapid absorption due to high vascularization and circumvention of the first pass effect. Aerosolization or inhalation of colloidal systems is currently being extensively studied and has huge potential for targeted drug delivery in the treatment of various diseases. Furthermore, the surfactant-associated proteins present at the interface enhance the effect of these formulations by decreasing the surface tension and allowing the maximum effect. The most challenging part of developing a colloidal system for nebulization is to maintain the critical physicochemical parameters for successful inhalation. The following review focuses on the current status of different colloidal systems available for the treatment of various lung disorders along with their characterization. Additionally, different in vitro, ex vivo and in vivo cell models developed for the testing of these systems with studies involving cell culture analysis are also discussed.

Preparation, characterization, and in vitro permeation study of terbinafine HCl in poloxamer 407-based thermogelling formulation for topical application.

Upon topical administration, a high penetration rate of antifungal drug into the infected site is desirable to reduce treatment length and systemic side effects which occur especially after a prolonged peroral administration. Thermogelling formulations composed of poloxamer 407, medium chain triglycerides, isopropyl alcohol, dimethyl isosorbide, and water for topical application were developed, and a lipophilic drug terbinafine HCl (TBF) was incorporated. Previously, a remarkable high permeation rate of a hydrophilic drug 5-aminolevulinic acid from this vehicle was evident compared to different creams from German Pharmacopoeia. By varying the composition of vehicle constituents, a broad range of consistencies and appearances was obtained. Up to 4% TBF could be solubilized in the vehicle. TBF fluxes at steady state across human stratum corneum from these formulations were higher than those from the German Pharmacopoeia Basiscreme Deutscher Arzneimittel Codex and a marketed product at similar concentration of 1%. TBF fluxes increased along with a higher content of TBF in the formulation. The amount of TBF retained in stratum corneum was higher compared to those from both standards of comparison (p < 0.01). The thermodynamic activity of TBF in the thermogelling formulation was lower compared to those in other formulations. Therefore, the nature of the vehicle and its interaction with TBF are suggested to play a significant role in explaining higher fluxes along with higher TBF content. Differential scanning calorimetry measurements revealed comparable T2 and T3 endothermic shifts from all examined formulations suggesting equal influences to the skin lipids.

Development of lipid-based microsuspensions for improved ophthalmic delivery of gentamicin sulphate.

Aim: Anterior eye segment disorders are treated with eye drops and ointments, which have low ocular bioavailability necessitating the need for improved alternatives. Lipid microsuspension of gentamicin sulphate was developed for the treatment of susceptible eye diseases. Materials & methods: Lipid microsuspensions encapsulating gentamicin sulphate were produced by hot homogenization and evaluated. Ex vivo permeation and ocular irritancy tests were also conducted. Results & conclusion: Stable microsuspensions with high entrapment efficiency and satisfactory osmolarities were obtained. Release studies achieved 49-88% in vitro release at 12 h with sustained permeability of gentamicin compared with conventional gentamicin eye drop (Evril®). No irritation was observed following Draize's test. The microsuspensions have great potential as ocular delivery system of gentamicin sulphate.

Phospholipids and lipid-based formulations in oral drug delivery.

Phospholipids become increasingly important as formulation excipients and as active ingredients per se. The present article summarizes particular features of commonly used phospholipids and their application spectrum within oral drug formulation and elucidates current strategies to improve bioavailability and disposition of orally administered drugs. Advantages of phospholipids formulations not only comprise enhanced bioavailability of drugs with low aqueous solubility or low membrane penetration potential, but also improvement or alteration of uptake and release of drugs, protection of sensitive active agents from degradation in the gastrointestinal tract, reduction of gastrointestinal side effects of non-steroidal anti-inflammatory drugs and even masking of bitter taste of orally applied drugs. Technological strategies to achieve these effects are highly diverse and offer various possibilities of liquid, semi-liquid and solid lipid-based formulations for drug delivery optimization.

An update on formulation strategies of benzoyl peroxide in efficient acne therapy with special focus on minimizing undesired effects.

Benzoyl peroxide (BPO) in the form of over the counter monotherapeutics or prescription-only combinations is a key component of topical acne therapy, but its unfavourable side effect profile reduces the therapeutic value of this compound. Various galenic approaches have been pursued to resolve this ambivalence, but only a few have managed to enter the market. This article aims to give a comprehensive overview of the published experimental vehicle systems and to identify the fundamental rationales. With regard to the formulation, an increase in the tolerability of BPO can essentially be achieved by combining BPO with re-fattening and moisturizing substances, by incorporating it and controlling its release, as well as by targeted deposition of the active ingredient at the site of action, i.e. drug targeting. Recently, novel particulate formulations have been proposed that combine several of these design principles and are expected to bring new developments in this dynamic field of research.

Antifungal efficacy of liquid poloxamer 407-based emulsions loaded with sertaconazole nitrate.

Drug delivery into the human nail plate for the treatment of onychomycosis is difficult due to limited permeability of the nail plate. Semisolid poloxamer 407-based formulations have recently shown promising results for drug delivery into and through the nail plate. In this study, liquid poloxamer 407-based emulsions loaded with sertaconazole nitrate have been developed and the permeation behavior was determined in vitro using modified Franz diffusion cells. The antifungal efficacy was evaluated in an infected nail plate model, where the growth inhibition of Trichophyton rubrum was observed. Bovine hoof plates and keratin films made from human hair were used as models for the human nail plate. In both cases, formulations with low viscosity and high water content showed best results despite a lower solubility of sertaconazole nitrate, suggesting that the composition of the vehicle plays a major role in permeation through the membrane. In addition, an API content close to saturation solubility had a positive effect on permeation.

Low cytotoxicity of solid lipid nanoparticles in in vitro and ex vivo lung models.

The aim of this study was to investigate the potential cytotoxicity of solid lipid nanoparticles (SLN) for human lung as a suitable drug delivery system (DDS). Therefore we used a human alveolar epithelial cell line (A549) and murine precision-cut lung slices (PCLS) to estimate the tolerable doses of these particles for lung cells. A549 cells (in vitro) and precision-cut lung slices (ex vivo) were incubated with SLN20 (20% phospholipids in the lipid matrix of the particles) and SLN50 (50% phospholipids in the lipid matrix of the particles) in increasing concentrations. The cytotoxic effects of SLN were evaluated in vitro by lactate dehydrogenase (LDH) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Vitality of lung slices was controlled by staining with calcein AM/ethidium homodimer 1 using confocal laser scanning microscopy and followed by quantitative image analysis with IMARIS software. A549 cell line revealed a middle effective concentration (EC(50)) for MTT assay for SLN20 of 4080 microg/ml and for SLN50 of 1520 microg/ml. The cytotoxicity in terms of LDH release showed comparable EC(50) values of 3431 microg/ml and 1253 microg/ml for SLN20 and SLN50, respectively. However, in PCLS we determined only SLN50 cytotoxic values with a concentration of 1500 microg/ml. The lung slices seem to be a more sensitive test system. SLN20 showed lower toxic values in all test systems. Therefore we conclude that SLN20 could be used as a suitable DDS for the lung, from a toxicological point of view.

Incorporation of benzoyl peroxide nanocrystals into adapalene-loaded solid lipid microparticles: Part II - Solid-in-Oil dispersion of nanoparticulate benzoyl peroxide.

Benzoyl peroxide as a monotherapeutic and in combination with adapalene is a cornerstone of current acne therapy, but its unfavourable side effect profile reduces the therapeutic value of this compound. The incorporation into an adapalene-loaded microparticulate lipid matrix, which - via the principle of targeted erosion - allows the targeted release of active substances in the hair follicles, is a promising approach to reduce side effects such as skin redness, increased scaling and allergic reactions. However, there are challenges to the production of such a vehicle which require a galenic solution. That is in particular the redispersion of nanoparticulate benzoyl peroxide in lipids while maintaining its nanodisperse character. In the present work, the lamellar liquid crystalline phase of a binary water/phospholipid system is used to stabilize a nanosuspension during freeze-drying. Both after redispersing in water and after dispersing in nonpolar fat phases, the initial size of the nanosuspension was recovered with only minor deviations. The found cryoprotective effect of purified phospholipid allows the generation of highly concentrated solid-in-oil systems both in fat phases liquid at room temperature and in lipid melts, which after solidification can serve as starting material for the preparation of lipid microparticles loaded with benzoyl peroxide nanocrystals.

Influence of emulsifier concentration on partition behavior and chemical stability of betamethasone dipropionate in emulsion gels.

The partitioning of active pharmaceutical ingredients (API) in emulsions is influenced by various factors, such as composition of the phases, emulsifier type and concentration, and temperature. Therefore, the chemical stability of the API can be influenced by its partitioning into the aqueous phase as degradation is typically facilitated in water. With increasing emulsifier concentration from 0.15% to 5.0%, more betamethasone dipropionate (BDP) was solubilized in polysorbate 80 micelles leading to a small, but increased fraction of BDP exposed to the aqueous phase along with preferential partitioning of BDP to the aqueous phase and thus increased degradation. Similarly, by enhancing solubility and partitioning to the aqueous phase, the addition of polyethylene glycol 400 also led to increased BDP degradation. Due to pH dependent degradation of BDP, increasing emulsifier concentrations resulted in a more pronounced degradation of BDP at pH 8, which is beyond the stability optimum, whereas at pH 5 the API was sufficiently stable and no differences in concentration were detected within 12 weeks even under accelerated conditions. No significant differences were seen with the varying emulsifier concentrations regarding ex vivo skin penetration.

Influence of pulse characteristics and power density on stratum corneum permeabilization by dielectric barrier discharge.

BACKGROUND: In recent years, the medical use of cold atmospheric plasma has received much attention. Plasma sources can be suited for widely different indications depending on their physical and chemical characteristics. Being interested in the enhancement of drug transport across the skin by plasma treatment, we evaluated three dielectric barrier discharges (DBDs) as to their potential use in permeabilizing human isolated stratum corneum (SC). METHODS: Imaging techniques (electrochemical and redox-chemical imaging, fluorescence microscopy), transepithelial electrical resistance measurements and permeation studies were employed to study the permeabilizing effect of different DBD-treatments on SC. RESULTS: Filamentous µs-pulsed DBDs induced robust pore formation in SC. Increasing the power of the µs-pulsed DBD lead to more pronounced pore formation but might increase the risk of undesired side-effects. Plasma permeabilization was much smaller for the ns-pulsed DBD, which left SC samples largely intact. CONCLUSIONS: The comparison of different DBDs provided insight into the mechanism of DBD-induced SC permeabilization. It also illustrated the need to tailor electrical characteristics of a DBD to optimize it for a particular treatment modality. For future applications in drug delivery it would be beneficial to monitor the permeabilization during a plasma treatment. GENERAL SIGNIFICANCE: Our results provide mechanistic insight into the potential of an emerging interdisciplinary technology - plasma medicine - as a prospective tool or treatment option. While it might become a safe and pain-free method to enhance skin permeation of drug substances, this is also a mechanism to keep in mind when tailoring plasma sources for other uses.

Physicochemical investigations of native nails and synthetic models for a better understanding of surface adhesion of nail lacquers.

The human nail, like any biological material, is not readily available in large amounts and shows some variability from one individual to another. Replacing it by synthetic models is of great interest to perform reproducible and reliable tests in order to assess drug diffusion or nail lacquer adhesion for example. Keratin films, produced at the lab scale from natural hair, and the commercially available Vitro-nail® sheets have been proposed as models of human nails. In this study, we have investigated in detail these two materials. Surface aspect, composition, surface energy and water permeation were determined by SEM-EDS, ATR-FTIR, XPS, DVS and tensiometry and were compared to those of nails clippings. The development of a probe tack test using a rotational rheometer allowed us to measure the adhesion of three different nail lacquers on each substrate and the results were correlated with the surface state. It is shown that except roughness, keratin films exhibit similar composition, water sorption and surface energy as human nails. Vitro-nail® presents a more hydrophilic and permeable behavior than natural nail due to probable higher proportions of amide functions and absence of disulfide bridges. With the aim to improve nail lacquer residence, the importance of adsorption, electrostatic and mechanical adhesions as well as water sorption behavior is highlighted and allowed to show the importance of roughness, a low surface energy, a moderate hydrophobicity and an ability to form hydrogen and electrostatic bonds in order to optimize adhesion.

Development of a design of experiments optimized method for quantification of polysorbate 80 based on oleic acid using UHPLC-MS.

The aim was to develop a straightforward UHPLC-MS quantification method for polysorbate 80 using oleic acid as surrogate marker, which was the commonest substance within the emulsifier. However, hydrolysis of polysorbate 80 and subsequent analysis of fatty acids revealed a co-elution of oleic acid and an isomer while all the other fatty acids were successfully separated by varying retention times and mass-to-charge ratios. For identification and separation of the isomer a derivatization method was evaluated. Oxidation to the corresponding dihydroxystearic acids with potassium permanganate resulted in peak separation of cis/trans and structural isomers of the 18:1 fatty acids. Hydrolyzed and derivatized polysorbate 80 was quantified indirectly in the range of 0.046-5.83 µg/mL (R2 > 0.997) with a limit of detection of 11.4 ng/mL. Quantification of polysorbate 80 using oleic acid as a surrogate marker showed good reproducibility and linearity. As all isomers of the 18:1 fatty acids were successfully separated, the previously co-eluting peak was identified as elaidic acid and was found as a component in the mixture of the emulsifier polysorbate 80. Additionally, cis-vaccenic acid was separated as a second co-eluting isomer. Therefore, derivatization led to successful chromatographical separation of cis/trans and structural 18:1 fatty acid isomers.