Search results for "permeation"
showing 10 items of 274 documents
Design of experiment approach for the optimization of polybrominated diphenyl ethers determination in fine airborne particulate matter by microwave-a…
2015
Abstract A sensitive and selective procedure for the determination of 12 polybrominated diphenyl ethers (BDE-28, BDE-49, BDE-47, BDE-66, BDE-100, BDE-119, BDE-99, BDE-155, BDE-154, BDE-153, BDE-139 and BDE-183) in airbone particulate matter (PM2.5) at trace level has been developed. The proposed method includes extraction PM2.5-bound PBDEs by microwave-assisted extraction (MAE) followed by gel permeation chromatography (GPC) clean-up and determination by GC-MS/MS using a programmed temperature vaporizer (PTV) in large volume injection (LVI) mode to introduce the sample to the chromatographic system. A design of experiment (DoE) approach was used for the optimization of large volume injectio…
Pyrolysis-GC-MS and CuO-oxidation-HPLC in the characterization of HMMs from sediments and surface waters downstream of a pulp mill
1998
Abstract High molecular mass fractions of lignin and humic compounds in sediments and waters downstream of a pulp mill were characterized applying pyrolysis-gas chromatography-mass spectrometry. The results were compared to those obtained using reversed phase HPLC on the cupric oxide oxidation products. The chromatographic data of both pyrolysis and cupric oxide oxidation were also subjected to the principal component analysis (PCA). The sediment samples and fractions obtained by ultrafiltration of river water samples were freeze dried prior to characterization. The sediment samples were also extracted using 2 M sodium hydroxide solution. The extracts were ultrafiltrated, freeze dried and c…
Skin permeation model of phenyl alcohols: comparison of experimental conditions
1998
Abstract This study was conducted primarily to establish the significance of the experimental conditions in the determination of permeability coefficients. In order to do this, standard in vitro skin permeation methods were used to determine the permeability coefficient (kp) of a homologous series of phenyl alcohols, with a wide range of lipophilicity, by two different experimental conditions through rat skin; first, using solutions (at 75% saturation concentration) of the penetrants in the donor compartment and second using saturated solutions added with an excess of the penetrant. The kp values obtained by these techniques were compared. Solubility of the phenyl alcohols in the donor phas…
Evaluation of Galantamine transbuccal absorption by reconstituted human oral epithelium and porcine tissue as buccal mucosa models: Part I
2008
Over the last decade, interest in delivering drugs through buccal mucosa has increased. As a major limitation in buccal drug delivery could be the low permeability of the epithelium, the aim of this study was to evaluate the aptitude of galantamine, useful in Alzheimer's disease, to penetrate the buccal mucosa. The evaluation of the ability of galantamine to permeate through the buccal epithelium was investigated using two permeation models. Firstly, in vitro permeation experiments were carried out using reconstituted human oral non-keratinised epithelium and Transwell diffusion cells system. Results were validated by ex vivo experiments using porcine buccal mucosa as membrane and Franz typ…
Comparative transcutaneous immunization with imiquimod-containing ointments and potential of in vitro methods to predict effects
2012
This work evaluates the transcutaneous in vitro and in vivo immunization efficacy of five commercially available 5% imiquimod containing formulations. The parameters included micro- scopic analysis, rheological properties, drug permeation across synthetic membranes of molecular weight cutoff 10kDa and ablated murine skin with both 0.1 M HCl and a phthalate buffer pH 3.6 Ph.Eur./methanol 3/7 (v/v) as receiver solutions in a Franz-diffusion cell model. For in vivo formu- lation characterization, the cytotoxic T-cell activity and interferon-g production in C57BL/6 mice was determined ex vivo 24h after transcutaneous administration. OVA257264 (SIINFEKL) from chicken al- bumin served as a target…
Influence of molecular weight and polydispersity on phase behaviour of polyesters with laterally fixed or cross-shaped mesogens
1991
Abstract To supplement previous studies of polyesters with laterally attached and cross-shaped mesogens the influence of molecular weight and molecular weight distribution on the phase behaviour has been investigated. For that purpose two polyesters have been fractionated by preparative gel permeation chromatography under high pressure and observed by polarizing microscopy and DSC measurements. A monotropic nematic polyester with laterally attached mesogens shows changing phase transitions up to a molecular weight of 10 000 (Mw); at higher molecular weight only the clearing transition is still slightly influenced. The molecular weight distribution at an average molecular weight of 15 000 (M…
Fouling mechanism elucidation in membrane bioreactors by bespoke physical cleaning
2018
Abstract Cake layer deposition on a membrane surface can determine both external and internal membrane fouling through negatively affecting the total filtration resistance while exerting a positive effect as a pre-filter. Membranes are usually subjected to a periodic cake layer removal through routine physical cleaning, specifically permeate backwashing of hollow fiber membranes, or enhanced cleaning through, for example, chemically-enhanced backwashing. Physical cake layer removal is crucial for sustaining permeability, yet the effect of different physical cleaning modes remains poorly evaluated. The present work attempts to analyze physical cake layer removal through the application of sp…
Nanoencapsulation in Lipid-Core Nanocapsules Controls Mometasone Furoate Skin Permeability Rate and Its Penetration to the Deeper Skin Layers
2013
<b><i>Aims:</i></b> The influence of nanoencapsulation of mometasone furoate (MF) in poly(ε-caprolactone) lipid-core nanocapsules (LNC) on its in vitro human skin permeation and penetration was evaluated. <b><i>Methods:</i></b> Semisolid formulations were prepared by increasing the viscosity of LNC using a carbomer (Carbopol® Ultrez at 0.5% w/v). Two complementary techniques (the static Franz diffusion cell model and the Saarbrücken penetration model) were used to evaluate skin permeation/penetration. <b><i>Results:</i></b> The drug release rate was decreased by nanoencapsulation. The skin permeability of MF was control…
Multistage recovery process of seaweed pigments: Investigation of ultrasound assisted extraction and ultra-filtration performances
2017
International audience; The objectives of this study were first to evaluate the performance of seaweed pigments’ recovery through ultrasound assisted extraction (UAE) and ultra-filtration (UF), and second to investigate the membrane fouling mechanism and evidence the threshold flux during filtration. The pigments’ recovery from the extract was performed using 5 kDa and 10 kDa ultra-filtration membranes. Results showed that increasing the extraction temperature in the range of 40–60 °C was proportional to chlorophyll extraction efficiency, while the maximal carotenoid yield was achieved at 50 °C. Ultrasonic power (from 100 W to 300 W) facilitated the extraction of both chlorophylls and carot…
Mucoadhesive PEGylated inulin-based self-assembling nanoparticles: In vitro and ex vivo transcorneal permeation enhancement of corticosteroids
2019
Abstract As transcorneal drug delivery is still a challenge, the scope of the present study was to prepare useful nanosystems able to enhance transcorneal permeation/penetration of drugs. Moreover, this work aims to evaluate the effectiveness of inulin-based nanosystems in the specific field of ocular drug delivery and the effect of PEG chains to promote mucoadhesion, stability and transcorneal penetration/permeation enhancer effect of self-assembling nanoparticles in vitro (transwell systems and HCE) and ex vivo (Franz cells and bovine cornea). In particular, inulin was chosen as the starting natural polysaccharide polymer to design a novel amphiphilic derivative named INU-EDA-RA-PEG capab…