Investigation of Perfluoroalkyl Bonded Alumina-based Stationary Phases for Reversed Phase High Performance Liquid Chromatography Applications PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Investigation of Perfluoroalkyl Bonded Alumina-based Stationary Phases for Reversed Phase High Performance Liquid Chromatography Applications PDF full book. Access full book title Investigation of Perfluoroalkyl Bonded Alumina-based Stationary Phases for Reversed Phase High Performance Liquid Chromatography Applications by Tina M. Mannschreck. Download full books in PDF and EPUB format.
Author: Tina M. Mannschreck
Publisher:
ISBN:
Category : Chromatographic analysis
Languages : en
Pages : 136
Get Book Here
Book Description
Author: Tina M. Mannschreck
Publisher:
ISBN:
Category : Chromatographic analysis
Languages : en
Pages : 136
Get Book Here
Book Description
Author: Veronica Ferguson
Publisher:
ISBN:
Category : High performance liquid chromatography
Languages : en
Pages : 120
Get Book Here
Book Description
Author: Omar Abubaker Rbeida
Publisher:
ISBN:
Category :
Languages : en
Pages : 123
Get Book Here
Book Description
The reversed-phase-silica bonded packing materials have been the most regularly used phases for the analysis of drugs and related substances for 3 decades. During that time they have been used in assay procedures and stability indicating assay method in dosage forms and in the biological fluids. However, these phases have continued to display disadvantages which effect their efficient operation which includes the solubility of the silica matrix and the detachment of the bonded layer at high and low pH ranges respectively, the difficulty to reproduce the same bonded stationary phases, and the major detrimental contribution of the silanol groups on the silica surface have affected also retention behaviour and stability of the assay. Therefore in this work the introduction of alternative stationary phases to substituted silica is considered. Alumina-bonded C,18, a Buckyclutcher column and a carbon fiber column have all been examined for their stability under aggressive conditions, and their retention behaviour and their capability to retain and resolve compounds better than silica bonded phases was studied. By using alumina C,18 stationary phase it was possible to resolve the amino alcohol, atenolol from its widely chemically different related substances and assay it in a tablet dosage form with good precision ....
Author: Anil R. Raghani
Publisher:
ISBN:
Category : Proteins
Languages : en
Pages : 166
Get Book Here
Book Description
Author: Michael David Bair
Publisher:
ISBN:
Category : Chemistry
Languages : en
Pages :
Get Book Here
Book Description
ABSTRACT: Central to the advancement of reversed-phase high-performance liquid chromatography (RPLC) is to develop new synthetic strategies for manufacturing stationary phase materials. Methods to improve the efficiency, retention properties, and chemical stability of stationary phases are always being investigated. The work presented focuses on two new synthesis schemes aimed at improving monomeric silica-based stationary phases in these respects. The first study involves "pre-capping" Type-B silica. Previous work showed that monomeric stationary phases made by pre-treating the silica surface with small amounts of trimethylsilane (TMS) reagents prior to C18 silanization showed vast improvements in the chromatographic efficiency, phase loading, and retention with a maximum at approx. 5% pre-capping. It was concluded that this pre-capping step improved efficiency by selectively neutralizing the most reactive highly-acidic silanol sites, so-called silanol "hot spots," producing a more energetically-homogenous surface prior to exhaustive C18 derivatization that subsequently yielded a more evenly-distributed alkyl bonding arrangement. These previous studies were performed on Type-A silica, an older variety of silica gel material containing higher levels of metal impurities than the Type-B silica used today. It has since been argued that metallic impurities are the primary cause of silanol hot-spots, and that pre-capping Type-B silica would have little or no effect, however the experimental evidence has yet to be produced, and there exists the potential for heterogeneous silanol reactivity inherent in the amorphous silica gel regardless of purity. The purpose of the work presented here is to determine the effects of TMS pre-capping on Type-B silica as compared to the previous Type-A results, with the goal of establishing pre-capping protocol for Type-B silica and to form a better understanding of its chemistry. The current work performed on three Type-B silica substrates of various physical and chemical properties demonstrated optimal TMS pre-capping at approximately 2.5%. The results at this level show only a slight improvement in efficiency for non-polar compounds ( 25%) was observed for some drug compounds and bases under buffered conditions, with the magnitude of the improved efficiencies correlating with metal impurity content and physical parameters of the silica substrate. Pre-capping also resulted in a slight decrease in retention and hydrolytic stability due to a decrease in bonded phase density. The results lend supporting evidence that metal impurities are the primary source of highly acidic silanols, but they also suggest a means to improve efficiency of basic analytes on certain Type-B silica substrates. It was concluded that TMS pre-capping Type-B silica is best done at low levels (
Author: Nirmala D. Ramdial
Publisher:
ISBN:
Category : Liquid chromatography
Languages : en
Pages : 0
Get Book Here
Book Description
Author: Eli Grushka
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 256
Get Book Here
Book Description
Author: Brian Charles Trammell
Publisher:
ISBN:
Category :
Languages : en
Pages : 370
Get Book Here
Book Description
Author: Kathleen Talbott
Publisher:
ISBN:
Category : High performance liquid chromatography
Languages : en
Pages : 77
Get Book Here
Book Description
The impact of chromatography across many scientific fields and applications is limitless. It is a vital everyday separation, characterization, and purification tool for many scientists worldwide. Innovations in high performance liquid chromatography (HPLC) stationary phases have led to more diverse separations essential to many fields including the pharmaceutical industry and research. Silica hydride based stationary phases have been shown to display both reverse phase (RP) and aqueous normal phase (ANP) chromatographic behavior. This is a result of both the silica hydride surface and the bonded phase. The goal of this work was to characterize silica hydride based diol stationary phases for HPLC. A wide range of compounds with varying polarities were analyzed. Retention was observed under ANP and RP conditions. Two representative silica hydride based diol stationary phases were compared to demonstrate the effect that the length of the bonded phase has on the separation capabilities of the column. The diol bonded phase with a longer carbon chain retained analytes with more hydrophobic (or non-polar) characteristics longer than analytes with more hydrophilic properties. As part of a larger study the effect of buffer concentration on the ANP retention of model compounds was investigated. Retention dramatically decreased when the concentration of some buffers was increased. This trend is opposite of what has been observed in hydrophilic interaction liquid chromatography (HILLIC), indicating a clear distinction in the retention mecahism for HILLIC and ANP.
Author: David C. Williams
Publisher:
ISBN:
Category : High performance liquid chromatography
Languages : en
Pages : 92
Get Book Here
Book Description
