Search results for "Sodium dodecyl sulfate"
showing 10 items of 146 documents
Control of propranolol intake by direct chromatographic detection of alpha-naphthoxylactic acid in urine.
2002
A rapid chromatographic procedure with a C18 column, a mobile phase of 0.15 M sodium dodecyl sulfate (SDS)-10% (v/v) 1-propanol at pH 3 (0.01 M phosphate buffer), and fluorimetric detection, is reported for the control of propranolol (PPL) intake in urine samples, which are injected directly without any other treatment than filtration. The peak of PPL was only observed in samples taken a few hours after ingestion of the drug due to its extensive conjugation and metabolisation. The detection of several unconjugated PPL metabolites was therefore considered: desisopropylpropranolol (DIP), propranolol glycol (PPG), alpha-naphthoxylactic acid (NLT) and alpha-naphthoxyacetic acid (NAC). NLT showe…
Analysis of basic drugs by liquid chromatography with environmentally friendly mobile phases in pharmaceutical formulations
2017
Abstract Basic drugs are positively charged in the usual working pH (2–8) in reversed-phase liquid chromatography. This gives rise to a strong association with the residual ionized silanols in conventional silica-based stationary phases, which is translated in poor peak shape and high consumption of organic solvent to get appropriate retention times. Micellar mobile phases containing surfactants give rise to modified stationary phases, where silanols are masked, improving the peak shape. However, mobile phases containing the anionic surfactant sodium dodecyl sulfate (SDS) require a small amount of organic solvent to conveniently decrease the retention of cationic analytes. An alternative is…
Nonlinear response of a batch BZ oscillator to the addition of the anionic surfactant sodium dodecyl sulfate.
2007
The response of the Belousov-Zhabotinsy (BZ) system to the addition of increasing amounts of the anionic surfactant sodium dodecyl sulfate (SDS) was monitored at 25.0 degrees C in stirred batch conditions. The presence of SDS in the reaction mixture influences the oscillatory parameters, i.e., induction period and oscillation period, to an extent that depends on the surfactant concentration. The experimental results have shown that the induction period increases slightly on increasing surfactant concentration and, then, a further increase in the [SDS] leads to an enhancement while the oscillation period increases monotonously on increasing SDS concentration. It has been proposed that the re…
Partitioning of macrocyclic compounds in a cationic and an anionic micellar solution: a small-angle neutron scattering study.
2004
Following a previous investigation on partitioning of some macrocycle compounds in sodium dodecyl sulfate (SDS) and dodecyltrimethylammonium bromide (DTAB) aqueous solutions and their effect on the micellar structure, a small-angle neutron scattering (SANS) study has been performed at fixed surfactant content (0.20 mol/L) and varying macrocycle concentrations from 0.20 up to 1.0 mol/L. Conductivity measurements have been also performed in order to evaluate the effect of the presence of macrocycles on the critical micellar concentration (cmc) of the two surfactants. SANS experimental data were fitted successfully by means of a core-plus-shell monodisperse prolate ellipsoid model. It has been…
Adsorption of the anionic surfactant sodium dodecyl sulfate on a C18column under micellar and high submicellar conditions in reversed-phase liquid ch…
2015
Micellar liquid chromatography makes use of aqueous solutions or aqueous-organic solutions containing a surfactant, at a concentration above its critical micelle concentration. In the mobile phase, the surfactant monomers aggregate to form micelles, whereas on the surface of the nonpolar alkyl-bonded stationary phases they are significantly adsorbed. If the mobile phase contains a high concentration of organic solvent, micelles break down, and the amount of surfactant adsorbed on the stationary phase is reduced, giving rise to another chromatographic mode named high submicellar liquid chromatography. The presence of a thinner coating of surfactant enhances the selectivity and peak shape, es…
Thermodynamics of Solubilization of Pentanol in Sodium Dodecyl Sulfate-Dodecyldimethylamine Oxide Mixed Micelles
1994
Abstract Heat capacity and density measurements of pentanol (PeOH)-sodium dodecyl sulfate (NaDS)-dodecyldimethylamine oxide-water mixtures were carried out at 0.03 m PeOH as a function of the total surfactants concentration (mc) at different ratios (XNaDS). From experimental data, the apparent molar volumes (VΦ,R) and heat capacities (CΦ,R) of PeOH in the surfactants mixture solutions were calculated. As a general feature, at a given mixture composition, VΦ,R increases monotonically with mt as observed in pure surfactants. In the cases of XNaDS = 0.1 and 0.3, VΦ,R drops at about 0.1 and 0.15 mt respectively. The decreasing CΦ,R VS mt curve shows peculiarities which were ascribed to the pres…
Calorimetric and viscosimetric investigation of the interaction between α,β-polyasparthydrazide and sodium dodecyl sulfate micelles
1993
Abstract The interaction between α,β-polyasparthydrazide (PAHy) and sodium dodecyl sulfate (SDS) micelles in aqueous solution was investigated by calorimetry and viscosimetry. The dependence of the enthalpic effect due to this interaction upon the surfactant concentration was rationalized in terms of a progressive binding of SDS micelles to the polymeric backbone. The analysis of the calorimetric data allow evaluation of the binding ability of SDS micelles to the polymeric chain. The viscosimetric behavior of SDS plus PAHy aqueous solutions, discussed in terms of the parameter F [F = ηrel(PAHy) + ηrel(PAHy) − ηrel(SDS+PAHy)], confirms the occurence of the interaction between SDS micelles an…
Reaggregation and binding of cell wall proteins from Candida albicans to structural polysaccharides
1998
Urea or hot sodium dodecyl sulphate extracted a significant amount of the same proteins from the matrix of the cell wall of the yeast form and mycelial cells of Candida albicans. Gel filtration analysis of the urea-extracted proteins revealed that they occurred in the form of large complexes which were unaffected by up to 8 M urea. Among them, proteins en route to becoming covalently associated within the wall scaffold were identified by their reaction with specific antibodies. When urea was removed by dialysis, some of these proteins specifically reassociated into large aggregates which bound strongly with ConA, whereas others remained soluble in smaller associated products. The ability of…
Performance and modelling of retention in microemulsion liquid chromatography
2020
Abstract The capability of liquid chromatography with microemulsions (MEs) as mobile phases was studied for the analysis of four parabens (butylparaben, ethylparaben, methylparaben, and propylparaben) and seven β-adrenoceptor antagonists (acebutolol, atenolol, carteolol, metoprolol, oxprenolol, propranolol, and timolol). MEs were formed by mixing aqueous solutions of the anionic surfactant sodium dodecyl sulphate, the alcohol 1-butanol that played the role of co-surfactant, and octane as oil. In order to guarantee the formation of stable MEs, a preliminary study was carried out to determine the appropriate ranges of concentrations of the three components. For this purpose, mixtures of varia…
Improving Fractionation of Human Milk Proteins through Calcium Phosphate Coprecipitation and Their Rapid Characterization by Capillary Electrophoresis
2018
This work describes a simple sample pretreatment method for the fractionation of human milk proteins (into their two main groups, whey and caseins) prior to their analysis. The protein-extraction protocol is based on the addition of calcium phosphate to nonadjusted pH human milk. The combination of calcium ions with phosphate results in an effective coprecipitation of caseins. To assess the suitability of this fractionation protocol, the protein extracts were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), LC-MS/MS, and capillary electrophoresis (CE) analysis. The results evidence a significant decrease in contamination of casein fraction with whey proteins…