Biomedical subjects

Mary W Kamande

Publications and source records attributed to Mary W Kamande.

4 recordsLinked to original sources

PubMed2005

Capillary electrochromatography using polyelectrolyte multilayer coatings.

This review covers recent progress in polyelectrolyte multilayer (PEM) coatings applied to analytical separations using open-tubular capillary electrochromatography (OT-CEC). The simple preparation procedure involved in the PEM approach has provided some attractive features over other modes of capillary electrophoresis-based separations including packed column capillary electrochromatography (PC-CEC) and micellar electrokinetic chromatography (MEKC). PEM coatings have been used to alleviate the adsorption of basic analytes, to improve separations, and to improve the stability of the electroosmotic flow. Fundamental aspects of PEM coatings on surfaces and analytical separation platforms are briefly outlined in this review. In addition, applications of PEM coatings to fused-silica capillaries or microchip separation devices for the separation of small achiral or chiral analytes, as well as large biomolecules, are discussed.

Journal Article↗

PubMed2004

Chiral separations using a polypeptide and polymeric dipeptide surfactant polyelectrolyte multilayer coating in open-tubular capillary electrochromatography.

A polyelectrolyte multilayer (PEM) coating consisting of the polypeptide, poly(l-lysine) hydrobromide, poly(l-lysine) and the polymeric dipeptide surfactant, poly(sodium undecanoyl-l-leucyl-alaninate), poly(l-SULA), is investigated as a new medium for the separation of chiral analytes in open-tubular capillary electrochromatography (OT-CEC). In this approach, a stable PEM is constructed in situ by alternative rinses of the cationic polymer poly(l-lysine) and the anionic polymer poly(l-SULA). In previous studies, the PEM coating has been constructed by use of the cationic polyelectrolyte poly (diallydimethylammonium chloride), PDADMAC. In this study, we investigate the use of a biopolymer as the cationic polyelectrolyte. The results reported here indicate an increase in selectivity and resolution when poly(l-lysine) is used as the cationic polymer in place of PDADMAC. To evaluate the chromatographic performance of the PEM coating as a chiral stationary phase, the separation of the beta-blockers, labetalol and sotalol, and the binaphthyl derivatives, 1,1'-bi-2-naphthyl-2,2'-dihydrogen phosphate, 1,1'-bi-2-naphthol, and 1,1-binaphthyl-2,2'-diamine, are investigated. In addition, the effect of varying the amino acid order of the polymeric dipeptide surfactant on resolution is investigated. The number of bilayers also significantly influences the separation efficiency and resolution of enantiomers. The run-to-run and capillary-to-capillary reproducibilities are evaluated by calculating the relative standard deviations (RSDs) of the electroosmotic flow. These RSD values were found to be less than 1%. The coating is also stable and allows more than 290 runs to be performed in the same capillary. In addition, coupling of this chiral OT-CEC column with mass spectrometry is investigated.

Chromatography, Micellar Electrokinetic Capillary↗

PubMed2004

Open-tubular capillary electrochromatography/electrospray ionization-mass spectrometry using polymeric surfactant as a stationary phase coating.

We describe the use of the polymeric surfactant poly(sodium undecylenic sulfate) (poly-SUS) as a stationary phase coating in open-tubular capillary electrochromatography (OT-CEC) coupled with electrospray ionization-mass spectrometry (ESI-MS) for the analysis of beta-blocker and benzodiazepine analytes. The production of a polymeric surfactant coating on the capillary inner wall involves (i) adsorption of the cationic polymer poly(diallyldimethylammonium chloride) (PDADMAC) to the inner surface of capillary, and (ii) adsorption of the negatively charged poly-SUS onto the cationic polymer layer via strong physical interaction of the two polymer layers. As compared with micellar electrokinetic chromatography (MEKC) coupled with ESI-MS, the main advantage of this proposed method is minimization of introduction of the monomeric or polymeric surfactant into the mass spectrometer, thus avoiding the interference of the nonvolatile micelle in ESI-MS. The effects of buffer pH and applied voltage on the separation of the analytes are also discussed. Under optimum conditions, four of the five beta-blockers and four benzodiazepines are separated.

Adrenergic beta-Antagonists↗

PubMed2003

Open-tubular capillary electrochromatography using a polymeric surfactant coating.

A stable polyelectrolyte multilayer (PEM) coating was investigated for use in open-tubular capillary electrochromatography (o-CEC). In this approach, the PEM consisted of the cationic polymer of a quaternary ammonium salt, poly(diallyldimethylammonium chloride) and the anionic polymeric surfactant, poly(sodium undecylenic sulfate). Both the cationic and anionic polymers were physically adsorbed to the surface of a fused-silica capillary by use of a simple coating procedure. This procedure involved an alternate rinse of the positively and negatively charged polymers. The performance of the PEM coating as a dynamic stationary phase was evaluated by use of electrochromatographic experiments and showed good selectivity for both phenols and benzodiazepines. Reproducibility of the PEM coating was also evaluated by calculating the relative standard deviations (RSDs) of the electroosomotic flow (EOF). The run-to-run and capillary-to-capillary RSD values of the EOF were less than 1.5%. The endurance of the coating was more than 100 runs. The importance of the PEM coating was illustrated by comparing separations on a bare uncoated capillary with the coated capillary. In addition, the chromatographic performance using o-CEC and micellar electrokinetic chromatography (MEKC) was compared for the separation of benzodiazepines.

Benzodiazepines↗