The Synthesis and Characterization of Reversed Phase Stationery Phases for High Performance Liquid Chromatography PDF Download
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Author: Karen Wink Barnes
Publisher:
ISBN:
Category : High performance liquid chromatography
Languages : en
Pages : 0
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Book Description
Author: Karen Wink Barnes
Publisher:
ISBN:
Category : High performance liquid chromatography
Languages : en
Pages : 0
Get Book Here
Book Description
Author: Karen Wink Barnes
Publisher:
ISBN:
Category : High performance liquid chromatography
Languages : en
Pages : 324
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Book Description
Reversed phase liquid chromatography (RPLC) is a widely used separation technique today. The stationary phase, composed of hydrocarbon moieties chemically bound to a silica support, is commonly prepared by refluxing the silica with a reactive silane in an appropriate solvent. Siloxane bonds, Si-O-Si, are formed. There are limitations to RPLC in that nonhomogeneous surface coverages, detrimental to efficient separations, result from the bonding process, and because the reaction is never complete due to steric restrictions. Also, silica is soluble at high pH values, and the Si-C bond binding the hydrocarbon to the silica is labile at low pH ranges. Thus, the usable pH range for silica stationary phases is 2.5 to 7.5, and often this range is too narrow to allow the separation of a mixture. The use of ultrasonic cavitation to catalyze silane bonding was investigated to dtermine whether the vigorous ultrasonic process would drive reagents into the surface pores and better distribute the hydrocar bonaceous reagent, thereby producing a more efficient stationary phase. Tandem reactions proved that ultrasonic bonding procedures are as effective as the refluxed, and that the chromatographic efficiency of the ultrasonic phases was comparable, if not superior, to the refluxed. Chromatographic tests also indicated the ultrasonic phases were comparable to commercially available phases. The reproducibility of the reactions and the effect of acoustic power and heat were also investigated. A second set of experiments investigated substitution of alumina for silica because the alumina crystalline structure remains intact over a pH range of 2 to 12. A trifunctional modification scheme generating a thick cross-linked hydrocarbon matte was used because the Al-0 bond is susceptible to hydrolysis, which strips the bound hydrocarbons, by polar RP solvents. Five aluminas were bonded and tested for chromatographic utility. Reaction conditions were optimized, and ultrasonic bonding was investigated. It was found that alumina with a sufficiently active surface is modifiable, and that the modified surface is remarkably stable for use with acidic and basic buffers and in neutral, polar solvent mixtures. The chromatographic utility of alumina phases was demonstrated and compared with the silica results.
Author: Dale Allen Shoemaker
Publisher:
ISBN:
Category :
Languages : en
Pages : 210
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Author: Niloofar Salehi
Publisher:
ISBN:
Category : High performance liquid chromatography
Languages : en
Pages : 129
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Book Description
High pressure liquid chromatography is one of the most frequently used methods for the separation of mixtures. Chemically modified silica hydride stationary phases, due to their unique selectivity and versatility, have been the focus of an increasing number of studies in the past several years. The objective of fabricating stationary phases with dual properties is to achieve separation of both polar and non-polar components in a single analysis. Due to an increasing demand in the fields of drug discovery, proteomics, and metabolomics to analyze numerous samples with a wide range of polarities, there is a need for more versatile stationary phases for a wide range of applications. In order to meet the above objective, in this research four novel silica hydride-based columns were synthesized using a hydrosilation procedure. The characterization of each column was done using a series of polar and nonpolar compounds by studying their aqueous normal phase and reversed-phase chromatographic behavior. Under these conditions, it turned out that two columns showed both RP and ANP behaviors. Of the remaining columns, one exhibited ANP behavior only and the other performed only in the reversed-phase mode.
Author: Steven Douglas Fazio
Publisher:
ISBN:
Category : Chromatographic analysis
Languages : en
Pages : 392
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Author: Zhuxu Wang
Publisher:
ISBN:
Category : Chemical bonds
Languages : en
Pages : 124
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Author: Louis W. Yu
Publisher:
ISBN:
Category : Aldehydes
Languages : en
Pages : 450
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Author: David S. Van Meter (III.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 179
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Book Description
Author: Hendrikus Antonius Claessens
Publisher:
ISBN: 9789038606583
Category : Art, Modern
Languages : en
Pages : 283
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Book Description
Author: Stavros Kromidas
Publisher: John Wiley & Sons
ISBN: 3527336818
Category : Science
Languages : en
Pages : 378
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Book Description
The rapid development of HPLC instrumentation and technology opens numerous possibilities - and entails new questions. Which column should I choose to obtain best results, which gradient fits to my analytical problem, what are recent and promising trends in detection techniques, what is state of the art regarding LC-MS coupling? All these questions are answered by experts in ten self-contained chapters. Besides these more hardware-related and technical chapters, further related areas of interest are covered: Comparison of recent chromatographic data systems and integration strategies, smart documentation, efficient information search in internet, and tips for a successful FDA inspection. This practical approach offers in a condensed manner recent trends and hints, and will also display the advanced reader mistakes and errors he was not aware of so far.
