Search results for "Micellar"
showing 10 items of 185 documents
Micellization properties of cardanol as a renewable co-surfactant
2015
With the aim to improve the features of surfactant solutions in terms of sustainability and renewability we propose the use of hydrogenated natural and sustainable plant-derived cardanol as an additive to com- mercial surfactants. In the present study we demonstrated that its addition, in amounts as high as 10%, to commercial surfactants of different charge does not significantly affect surfactant properties. Conversely, the presence of hydrogenated cardanol can strongly affect spectrophotometric determination of CMC if preferential interactions with the dyes used take place. This latter evidence may be profitably exploited in surfactant manufacturing by considering that the concurrent pres…
Micellar electrokinetic chromatography of polyamines and monoacetylpolyamines
2001
A selective procedure for qualitative and quantitative analysis of ten polyamines by micellar electrokinetic chromatography (MEKC) was developed. Benzoylated polyamines and acetylpolyamines in micellar phase of SDS (10 mM) were separated at 25 degrees C by 20 mM borate buffer pH 8.5, containing 8% ethanol, with an applied voltage of 25 kV (5 microA) and then detected at 198 nm. The experimental factors and operational parameters were optimized by performing analysis at different surfactant concentrations, pH, voltage and temperature with and without ethanol. The repeatibility of migration times and peak heights is a peculiarity of the method here described.
Analysis of pharmaceutical preparations containing antihistamine drugs by micellar liquid chromatography
2005
Rapid chromatographic procedures for analytical quality control of pharmaceutical preparations containing antihistamine drugs, alone or together with other kind of compounds are proposed. The method uses C18 stationary phases and micellar mobile phases of cetyltrimethylammonium bromide (CTAB) with either 1-propanol or 1-butanol as organic modifier. The proposed procedures allow the determination of the antihistamines: brompheniramine, chlorcyclizine, chlorpheniramine, diphenhydramine, doxylamine, flunarizine, hydroxyzine, promethazine, terfenadine, tripelennamine and triprolidine, in addition to caffeine, dextromethorphan, guaifenesin, paracetamol and pyridoxine in different pharmaceutical …
The solubilisation behaviour of some dichloroalkanes in aqueous solutions of PEO-PPO-PEO triblock copolymers: a dynamic light scattering, fluorescenc…
2006
The aggregation behaviour of PEO-PPO-PEO triblock copolymers in water and in water + chlorinated additive mixtures was studied by means of fluorescence spectroscopy, dynamic light scattering (DLS), and small-angle neutron scattering (SANS). The copolymers were chosen such as to investigate the effects of molecular architecture (L35 and 10R5) and molecular weight by keeping constant the hydrophilic/hydrophobic balance (F88 and F108). 1,2-Dichloroethane was used as a prototype of water basins contaminants. The hydrodynamic radius of the block copolymer aggregates (R(h,M)) and the intensity ratio of pyrene of the first and the third vibrational band (I(1)/I(3)) were determined as a function of…
Micellar liquid Chromatographic determination of diuretics by diazotization and coupling with the Bratton-Marshall reagent
1997
Abstract A Chromatographic procedure that uses micellar mobile phases of sodium dodecyl sulphate (SDS) and propanol at pH 3 is reported for the determination, in urine samples, of thiazide diuretics (althiazide, bendroflumethiazide, chlorothiazide, hydrochlorothiazide, hydroflumethiazide, and trichloromethiazide), and other diuretics having a sulphonamide substituent in the benzene ring. Precolumn derivatization with sodium nitrite and N -(1-naphthyl)ethylenediamine, to form the coloured azo dyes of the hydrolyzed diuretics, decreased the polarity of the compounds and, consequently, their retention in the micellar eluents, and permitted detection in the visible region, eliminating thus the …
In vitro evaluation of poloxamer in situ forming gels for bedaquiline fumarate salt and pharmacokinetics following intramuscular injection in rats
2019
Graphical abstract
Determination of urea-derived pesticides in fruits and vegetables by solid-phase preconcentration and capillary electrophoresis
2001
A multiresidue analytical method based on solid-phase extraction (SPE) enrichment combined with capillary electrophoresis (CE), using micellar electrokinetic capillary chromatography (MEKC), was developed to determine ten substituted urea pesticides in orange and tomato samples. Several factors such as pH, composition and concentration of the buffer, concentration of surfactant, addition of organic solvent, and working voltage were optimized to obtain the best compound separation in the shortest time. Separation can be achieved in 7 min using a micellar aqueous pH 9 buffer composed of 4 mM borate and 35 mM sodium dodecyl sulfate. After an SPE procedure, which provided a 10-fold enrichment, …
Effect of ionization and the nature of the mobile phase in quantitative structure-retention relationship studies.
2005
Abstract The octanol–water distribution constant, commonly called partition coefficient, Po/w, is a parameter often retained as a measure of the hydrophobicity of a molecule. log Po/w, for a given molecule, can be conveniently evaluated constructing correlation lines between standard retention factor logarithms (log k) in reversed-phase liquid chromatography (RPLC) and standard log Po/w values. Many compounds of pharmaceutical interest can be quite hydrophobic and have, simultaneously, basic nitrogen atoms or acidic sulfur containing groups in their structure. This renders them ionizable. The hydrophobicity of the molecular drug form (Po/w value) is completely different from its ionic form …
Effect of sodium dodecyl sulphate and Brij-35 on the analysis of sulphonamides in physiological samples using direct injection and acetonitrile gradi…
2016
Micellar liquid chromatography (MLC) is a reversed-phase (RP) mode, which often does not require gradient elution, since the peaks of mixtures of compounds within a large range of polarities appear more evenly distributed in the chromatograms of isocratic elution, giving rise to a “gradient effect”. However, the use of a gradient of organic solvent may still be convenient to shorten the total analysis time. This work compares the separation of 15 sulphonamides using conventional hydro-organic RPLC and MLC with the surfactants sodium dodecyl sulphate (SDS) and Brij-35, and both isocratic and gradient elution with acetonitrile. The observed behaviour is rationalized attending to the interacti…
Quality control of pharmaceuticals containing non-steroidal anti-inflammatory drugs by micellar liquid chromatography
2002
A liquid chromatographic procedure is described for the determination of acemetacin, diclofenac, indomethacin, ketoprofen, nabumetone, naproxen, piketoprofen, and tolmentin in pharmaceutical preparations. The compounds were separated on a Kromasil C18 analytical column, with a guard column of similar characteristics; the mobile phase was 0.06 M cetyltrimethylammonium bromide, at pH 7, containing 10% 1-butanol. At a flow rate of 1 mL min−1 the elution time of the most retained compound was 23 min. Limits of detection were between 0.01 μ g mL−1 for diclofenac and 0.2 μ g mL−1 for naproxen. The proposed method enables the determination of non-steroidal anti-inflammatory drugs in pharmaceutical…