PubMed Health⌕ Search

Biomedical subjects

Apryll M Stalcup

Publications and source records attributed to Apryll M Stalcup.

6 recordsLinked to original sources
PubMed2006

Mobile phase effects on retention on a new butylimidazolium-based high-performance liquid chromatographic stationary phase.

A new HPLC stationary phase based on n-butylimidazolium bromide has been characterized by a linear solvation energy relationship (LSER) approach in the binary acetonitrile/water mobile phases. The retention properties of the stationary phase were systematically evaluated in terms of intermolecular interactions between 28 test solutes and the stationary phase. The results and further comparisons with conventional reversed phase system confirm that retention properties are similar to phenyl phases in acetonitrile/water mixtures. The results obtained with acetonitrile/water mixtures are also compared with results obtained using methanol/water mixtures.

Acetonitriles↗
PubMed2006

Analytical performance of polymer-based microfluidic devices fabricated by computer numerical controlled machining.

A study comparing the electrophoretic separation performance attainable from microchips molded by masters fabricated using conventional CNC machining techniques with commercial microchips, wire imprinted microchips, and microchips from LIGA molding devices is presented. An electrophoresis-based detection system using fluorescence microscopy was used to determine the analytical utility of these microchips. The separation performance of CNC microchips was comparable to commercially available microchips as well as those fabricated from LIGA masters. The important feature of the CNC machined masters is that they have rapid design-to-device times using routinely available machining tools. This low-cost prototyping approach provides a new entry point for researchers interested in thermoplastic microchips and can accelerate the development of polymer-based lab-on-a-chip devices.

Computer-Aided Design↗
PubMed2005

An online fiber-optic UV-visible detector for continuous free-flow electrophoresis.

A PC-controlled, scanning online UV detector for continuous free-flow electrophoresis (CFFE) was designed to allow for single UV wavelength monitoring across a 1-D array of 48 longitudinal flow cells interfaced to a CFFE apparatus. In the detection scheme, the UV light is sequentially passed through each of the flow cells. The design integrates online acquisition of absorbance spectra of components separated by CFFE. Benzoic acid standard solutions were used to examine the performance of the detector. Chloroquine diphosphate and 4-nitrophenol were used as test solutes to determine the detector's ability to distinguish analytes separated in the CFFE.

Electrophoresis↗
PubMed2003

Comprehensive strategy for chiral separations using sulfated cyclodextrins in capillary electrophoresis.

This review focuses on the emerging role of sulfated cyclodextrins in the capillary electrophoretic (CE) separation of chiral analytes. Since being introduced as enantioselective agents for CE in 1995, these anionic additives have continued to demonstrate remarkable application universality. The broad spectrum of chiral compounds successfully separated using this approach includes acidic, basic, neutral, and zwitterionic species. This impressive array of analyte structures is derived from a growing diversity of compound classes including pharmaceuticals, plant extracts, biomarkers, herbicides, alkaloids, fungicides, and metal ions. Moreover, literature reports highlight the minimal optimization required to achieve a successful separation. Based on these findings, sulfated cyclodextrins appear to be well suited for the development of a more universal, comprehensive separation strategy for chiral compounds. This review explores this proposition by beginning with the structure and migration properties of sulfated cyclodextrins, using applications to highlight the separating power of this technique and ending with a pragmatic, comprehensive separation strategy.

Animals↗
PubMed2002

Optimization of preparative electrophoretic chiral separation of ritalin enantiomers.

Continuous free flow electrophoresis (CFFE) was applied to the preparative chiral separation of ritalin enantiomers. Sulfated beta-cyclodextrin (sbeta-CD) was used as the chiral additive. Liquid chromatography-mass spectrometry (LC-MS) experiments were applied to study the time averaged concentration of sbeta-CD in the separation chamber. The distribution of sbeta-CD in the separation chamber greatly influenced resolution and the angle of deflection. To optimize the separation, several parameters (methanol, concentration of sbeta-CD in the cathodic wash and in the separation buffer, and the introduction of a low conductivity zone) were investigated. The dependence of the resolution and deflection angles of ritalin enantiomers on the concentration of sbeta-CD in both the separation buffer and in the cathode wash solution appeared to be non-linear. Under close to optimal conditions, resolution of ritalin enantiomers was about 0.8 with an average processing rate of 0.5 mg/h. Overall, the enantiomeric purity of the individual isomers was approximately 83%; however, of the 20 vials containing ritalin, the presence of both enantiomers was only detected in three vials.

Central Nervous System Stimulants↗