Author: Louis W. Yu
Publisher:
ISBN:
Category : Aldehydes
Languages : en
Pages : 450
Book Description
The Synthesis and Characterization of Bonded Zwitterionic Stationary Phases for High Performance Liquid Chromatography
Author: Louis W. Yu
Publisher:
ISBN:
Category : Aldehydes
Languages : en
Pages : 450
Book Description
Publisher:
ISBN:
Category : Aldehydes
Languages : en
Pages : 450
Book Description
The Synthesis and Characterization of Bonded Stationary Phases in High Performance Liquid Chromatography
Author: Steven Douglas Fazio
Publisher:
ISBN:
Category : Chromatographic analysis
Languages : en
Pages : 392
Book Description
Publisher:
ISBN:
Category : Chromatographic analysis
Languages : en
Pages : 392
Book Description
The Synthesis and Characterization of Reversed Phase Stationary Phases for High Performance Liquid Chromatography
Author: Karen Wink Barnes
Publisher:
ISBN:
Category : High performance liquid chromatography
Languages : en
Pages : 324
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.
Publisher:
ISBN:
Category : High performance liquid chromatography
Languages : en
Pages : 324
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.
The Synthesis and Characterization of Homopolypeptide Bonded Stationary Phases for Liquid Chromatography
Author: Barbara Ann Siles
Publisher:
ISBN:
Category :
Languages : en
Pages : 490
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 490
Book Description
Synthesis and Characterization of Liquid Crystal-like Stationary Phases for High Performance Liquid Chromatography
Author: Zhuxu Wang
Publisher:
ISBN:
Category : Chemical bonds
Languages : en
Pages : 124
Book Description
Publisher:
ISBN:
Category : Chemical bonds
Languages : en
Pages : 124
Book Description
Synthesis and Characterization of Surface-confined Ionic Liquid Stationary Phases for High Performance Liquid Chromatography
Author: David S. Van Meter (III.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 179
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 179
Book Description
Synthesis and Characterization of New Bonded Stationary Phases for HPLC
Author: Deepika Janga
Publisher:
ISBN:
Category : High performance liquid chromatography
Languages : en
Pages : 154
Book Description
Publisher:
ISBN:
Category : High performance liquid chromatography
Languages : en
Pages : 154
Book Description
Synthesis and Characterization of C8 Bonded Stationary Phases for HPLC
Author: Xiaofang Pan
Publisher:
ISBN:
Category : High performance liquid chromatography
Languages : en
Pages : 170
Book Description
Publisher:
ISBN:
Category : High performance liquid chromatography
Languages : en
Pages : 170
Book Description
The Synthesis and Characterization of Reversed Phase Stationery Phases for High Performance Liquid Chromatography
Author: Karen Wink Barnes
Publisher:
ISBN:
Category : High performance liquid chromatography
Languages : en
Pages : 0
Book Description
Publisher:
ISBN:
Category : High performance liquid chromatography
Languages : en
Pages : 0
Book Description
Synthesis and Characterization of Stationary Phases for Reversed-phase Liquid Chromatography
Author: Dale Allen Shoemaker
Publisher:
ISBN:
Category :
Languages : en
Pages : 210
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 210
Book Description