Chye Peng Ong

Retention of eleven priority phenols using micellar electrokinetic chromatography

The use of micellar electrokinetic chromatography (MECC) for the separation of eleven substituted phenols listed by the United States Environmental Protection Agency as priority pollutants was investigated. Solutions of potassium and sodium dodecyl sulphate in phosphate-borate buffer of pH 6.6, 7.0 and 7.5 were used as the electrophoretic media. Satisfactory separation of the eleven phenols was obtained using a 180-microns capillary at 10 kV and pH 6.6 with a solution containing both sodium and potassium dodecyl sulphate. Observations on the retention behaviour of the phenols in MECC were related to their physico-chemical properties.

Optimization of mobile phase composition for high-performance liquid chromatographic analysis of eleven priority substituted phenols.

The aim of the optimization scheme is to predict the best mobile phase composition consisting of mixtures of water with various proportions of three common organic modifiers, methanol, acetonitrile and tetrahydrofuran

Separation of polycyclic aromatic hydrocarbons by micellar electrokinetic chromatography with cyclodextrins as modifiers

Abstract The use of α-, β- and γ-cyclodextrins as modifiers to the electrophoretic medium containing sodium dodecyl sulphate and a phosphate-borate buffer in the micellar electrokinetic chromatography of polycyclic aromatic hydrocarbons (PAHS) was investigated. The results showed that the migration behaviour of PAHs could be related to their sizes and the cavity sizes of the cyclodextrins. With the addition of γ-cyclodextrin higher selectivity could be achieved, which consequently resulted in better separation of the seven PAHs investigated.

Determination of antihistamines in pharmaceuticals by capillary electrophoresis.

Capillary electrophoresis with on-column UV detection at 214 nm was used to separate a group of nine antihistamines. All these compounds were satisfactorily separated within ca. 6 min using a mixed carrier system containing sodium dodecyl sulphate with beta-cyclodextrin and tetrabutylammonium hydrogensulphate as modifiers. The application of the method to the determination of the amount of antihistamines present in commercial pharmaceutical samples was demonstrated. In addition, the migration behaviour of the antihistamines in the mixed carrier system was examined.

Separation of Dns-amino acids and vitamins by micellar electrokinetic chromatography

Abstract Fifteen Dns-amino acids were analysed by micellar electrokinetic chromatography (MEKC). All the amino acids were satisfactorily separated within ca . 26 min with 40 m M sodium dodecyl sulphate in phosphate—borate bufrer (pH 7.56). The migration behaviour of the amino acids at different pH values and SDS concentrations was examined. In addition, attempts were made to separate a mixture of amino acids and vitamins simultaneously in a single run by MEKC. Detection for this mixture was carried out with an on-column fluorescence detection system with the capability of performing multi-wavelength programming.

Separation of phthalates by micellar electrokinetic chromatography

Abstract Micellar electrokinetic chromatography (MEKC) of priority phthalate esters was investigated. A commercial photodiode-array ultraviolet—visible detector was modified for on-column detection in an MEKC system. For the separation of phthalate esters, electrophoretic media with sodium dodecyl sulphate in phosphate—borate buffer were used. The retention behaviour of the phthalate esters at different concentrations of micellar solution and at different pH values of the electrophoretic media was investigated. In addition, the effect of different voltages across the capillary tubing was examined. The results successfully demonstrated the application of MEKC for the separation of a group of six phthalate esters, five of which are priority pollutants.

Migration behaviour of catechols and catecholamines in capillary electrophoresis

Abstract The migration behaviour of selected catechols and catecholamines in micellar electrokinetic chromatography (MEKC) was investigated. For the MEKC separation of the compounds, electrophoretic media with sodium dodecyl sulphate in phosphate—borate buffer were used. The migration behaviour of the catechols and catecholamines at different concentrations of micellar solution and at different pH of the electrophoretic media was investigated. The results successfully demonstrated the use of MEKC for the separation of a mixture of two catechols and six catecholamines.

Optimization of mobile phase composition for high-performance liquid chromatographic separation by means of the overlapping resolution mapping scheme

Abstract The use of the overlapping resolution mapping (ORM) scheme to predict the optimum mobile phase composition for isocratic reversed-phase separation was examined. The application of the method to the separation of a mixture of ten polycyclic aromatic hydrocarbons was demonstrated. The ORM scheme was found to be a rapid and versatile method.

Direct coupling of supercritical fluid extraction-supercritical fluid chromatography for the determination of selected polycyclic aromatic hydrocarbons in aqueous environmental samples

A rapid and simple method is described for the quantitative determination of polycyclic aromatic hydrocarbons in aqueous environmental samples. A microscale on-line supercritical fluid extraction-supercritical fluid chromatography system using carbon dioxide is employed. The extract is analysed using capillary supercritical fluid chromatography with UV detection. Detection was carried out at 254 nm. An extraction efficiency of as high as 91% was obtained for the PAHs.

Analysis of Priority Substituted Phenols by Micellar Electrokinetic Chromatography

The use of micellar electrokinetic capillary chromatography (MECC) for the separation of eleven substituted phenols listed by the United States Environmental Protection Agency as priority pollutants was demonstrated. The effects of the pH and ionic strength of the buffer, and the length of the separation column on resolution were investigated. The retention characteristics of the eleven phenols in MECC are discussed.