Search results for "Sodium Dodecyl Sulfate"
showing 10 items of 146 documents
Prediction of peak shape in hydro-organic and micellar-organic liquid chromatography as a function of mobile phase composition
2007
A simple model is proposed that relates the parameters describing the peak width with the retention time, which can be easily predicted as a function of mobile phase composition. This allows the further prediction of peak shape with global errors below 5%, using a modified Gaussian model with a parabolic variance. The model is useful in the optimisation of chromatographic resolution to assess an eventual overlapping of close peaks. The dependence of peak shape with mobile phase composition was studied for mobile phases containing acetonitrile in the presence and absence of micellised surfactant (micellar-organic and hydro-organic reversed-phase liquid chromatography, RPLC). In micellar RPLC…
Peak half-width plots to study the effect of organic solvents on the peak performance of basic drugs in micellar liquid chromatography.
2009
The addition of the anionic surfactant sodium dodecyl sulphate (SDS) to hydro-organic mixtures of methanol, ethanol, propanol or acetonitrile with water yielded enhanced peak shape (i.e. increased efficiencies and symmetrical peaks) for a group of basic drugs (β-blockers) chromatographed with a Kromasil C18 column. The effect can be explained by the thin layer of surfactant associated to the hydrocarbon chain on the stationary phase in the presence of the organic solvents, which covers the free silanols on the siliceous support avoiding their interaction with the cationic basic drugs. These instead interact with the anionic head of the surfactant increasing their retention and allowing a mo…
Analysis of tear proteins by one- and two-dimensional thin-layer iosoelectric focusing, sodium dodecyl sulfate electrophoresis and lectin blotting. D…
1998
· Background: Isoelectric focusing (IEF) of tear proteins has not yet been carried out in a satisfactory way. Two-dimensional (2D) electrophoresis, especially in the combination of IEF with SDS, is able to differentiate between proteins in detail. The purpose of this study was therefore to analyze tear proteins by 1D IEF alone and in combination with a 2D pattern, and by IEF followed by lectin staining. · Methods: Ampholines, covering a broad range from pH 3 to pH 10, were applied. After IEF, semi-dry blotting and incubation with a group II lectin and two group V lectins was performed. · Results: Tear proteins could be separated into 31 single bands. Tear-specific pre-albumin (TSPA), lactof…
Interpretive search of optimal isocratic and gradient separations in micellar liquid chromatography in extended organic solvent domains
2020
Abstract Micellar liquid chromatography (MLC) is a reversed-phase mode with mobile phases containing an organic solvent and a micellised surfactant. Most procedures developed in MLC are implemented in the isocratic mode, since the general elution problem in chromatography is less troublesome. However, gradient elution may be still useful in MLC to analyse mixtures of compounds within a wide range of polarities, in shorter times. MLC using gradients is attractive to determine by direct injection moderate to low polar compounds in physiological samples. In these analyses, the use of initial micellar conditions (isocratic or gradient) with a fixed amount of surfactant above the critical micell…
Micellar Liquid Chromatography: A Worthy Technique for the Determination of β-Antagonists in Urine Samples
1998
Several beta-antagonists (acebutolol, atenolol, celiprolol, labetalol, metoprolol, nadolol, propranolol) were determined in urine samples with fluorometric detection after direct injection, in less than 15 min, with a micellar mobile phase of 0.1 M sodium dodecyl sulfate (SDS), 15% propanol, and 1% triethylamine at pH 3. The limits of detection (38 criterion) were usually between 3 and 30 ng/mL. The addition of propanol and triethylamine and the reduction of the pH of the mobile phase improved the efficiency of the chromatographic peaks that was rather low in pure micellar eluents. The selection of the composition of the mobile phase was easily performed through the use of an interpretive p…
Enhancing effect of alpha-hydroxyacids on "in vitro" permeation across the human skin of compounds with different lipophilicity.
2005
The percutaneous penetration-enhancing effects of glycolic acid, lactic acid and sodium lauryl sulphate through the human epidermis was investigated using 5-fluorouracil as a hydrophilic model permeant and three compounds belonging to the phenylalcohols: 2-phenyl-ethanol, 4-phenyl-butanol and 5-phenyl-pentanol. The lipophilicity values of the compounds ranged from log Poct -0.95 to 2.89. The effect of the enhancer concentration was also studied. Skin pretreatment with aqueous solutions of the three enhancers did not increase the permeability coefficient of the most lipophilic compound (log Poct = 2.89). For the other compounds assayed, the increase in the permeability coefficients depended …
Enzymatic modification of low-density lipoprotein in the arterial wall: a new role for plasmin and matrix metalloproteinases in atherogenesis.
2004
Objective— Functionally interactive proteases of the plasminogen/plasmin and the matrix metalloproteinase (MMP) system degrade and reorganize the extracellular matrix of the vessel wall in atherosclerosis. Here we investigated whether such proteases are able to confer atherogenic properties onto low density lipoprotein by nonoxidative modification. Methods and Results— Similar to the recently described enzymatically-modified low-density lipoprotein (E-LDL), native LDL exposed to plasmin or matrix MMP-2 or MMP-9 and cholesterylester-hydrolase (CEH) showed extensive deesterification, with ratios of free cholesterol to total cholesterol rising to 0.8 compared with 0.2 in native LDL. When the …
Simultaneous sodium lauryl sulphate testing improves the diagnostic validity of allergic patch tests. Results from a prospective multicentre study of…
2005
Summary Background There is evidence that a higher skin susceptibility may induce nonspecific erythematous or weak positive reactions to contact allergens in patch testing. Objectives To evaluate whether simultaneous application of sodium lauryl sulphate (SLS) along with diagnostic patch tests with contact allergens can provide information regarding skin irritability which may help to discriminate allergic from nonspecific irritant reactions to contact allergens. Methods Between July 2001 and June 2003, this prospective study collected patch test data of 5971 patients from 19 centres in Germany and Austria in the Information Network of Departments of Dermatology (IVDK). In addition to co…
The MOAHLFA index of irritant sodium lauryl sulfate reactions: first results of a multicentre study on routine sodium lauryl sulfate patch testing
2004
In a multicentre study of the German Contact Dermatitis Research Group, sodium lauryl sulfate (SLS) 0.25% and 0.5% aq. has been added to routine allergen patch tests to assess its properties as a convenient diagnostic indicator of individual susceptibility to irritation at the time of patch testing. Previous studies indicated that irritant SLS reactivity may be related to individual factors such as age and sex. As these factors are, in turn, among the important predictors of contact allergy to many allergens, e.g. summarized in the 'MOAHLFA index', the impact of the MOAHLFA factors on irritant SLS patch test reactivity, and thus a potential for confounding, was assessed in the 5971 particip…
Sputum metalloproteinase-9/tissue inhibitor of metalloproteinase-1 ratio correlates with airflow obstruction in asthma and chronic bronchitis
1998
Asthma and chronic bronchitis are inflammatory diseases with extracellular matrix (ECM) remodeling and collagen deposition. Collagen homeostasis is controlled by metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). We evaluated MMP and TIMP balance in induced sputum of 10 control, 31 untreated asthmatic, and 16 chronic bronchitic subjects. We first performed zymographic analysis to identify the profile of MMPs. Zymography revealed a similar MMPs profile in all populations studied and that MMP-9 was the major enzyme released. We then measured, using enzyme immunoassay, the concentrations of MMP-9 and of its inhibitor TIMP-1 and evaluated whether airflow limitation m…