Factors affecting the selectivity and efficiency of solid phase extraction of ionizable compounds

Persistent Link:
http://hdl.handle.net/10150/282287
Title:
Factors affecting the selectivity and efficiency of solid phase extraction of ionizable compounds
Author:
Mann, Thierry Dominic
Issue Date:
1996
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Solid phase extraction (SPE) is an extension of conventional liquid chromatographic methods. In the case of SPE the desired separation is digital in nature. Under one solvent condition total retention occurs while under a second solvent condition total elution occurs. The role of SPE as a sample preparation tool is becoming more dominant in the field of analytical chemistry. The need for high throughput, decreased solvent usage, and automation makes SPE the method of choice over other extraction methods. Ionic interactions at modified silica sorbents are studied with respect to the impact on the isolation and purification of analytes. The interactions are characterized by quantitating absolute recoveries for a variety of analytes under different conditions, and qualitative analysis of analytical interferences. Extractions of ionizable compounds were found to be dependent on a myriad of factors. These factors include sample pH, buffer composition, solution concentration, and elution solvent composition. Selectivities for ionizable analytes can be increased by utilizing ionic interactions, particularly in a mixed-mode operation. The extraction of basic compound compounds is generally robust, while methods for the acidic analytes are more highly dependent on the type of counter-ion. Ion selectivities observed were different than those recorded for polymer-based ion-exchange sorbents. The organization of water in the near surface region of the silica-based sorbents is the reason for the disparity between the two types of materials. The utility of a polymeric polystyrene divinylbenzene sorbent for the analysis of analytes from biological matrices is demonstrated. It was shown that these sorbents can withstand harsh chemical environments that would preclude using a silica-based material. Analysis times were shortened and extraction efficiencies were comparable to the silica materials. The extractions were not as selective as those performed on mixed-mode sorbents however.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Chemistry, Analytical.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Chemistry
Degree Grantor:
University of Arizona
Advisor:
Burke, Michael F.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleFactors affecting the selectivity and efficiency of solid phase extraction of ionizable compoundsen_US
dc.creatorMann, Thierry Dominicen_US
dc.contributor.authorMann, Thierry Dominicen_US
dc.date.issued1996en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractSolid phase extraction (SPE) is an extension of conventional liquid chromatographic methods. In the case of SPE the desired separation is digital in nature. Under one solvent condition total retention occurs while under a second solvent condition total elution occurs. The role of SPE as a sample preparation tool is becoming more dominant in the field of analytical chemistry. The need for high throughput, decreased solvent usage, and automation makes SPE the method of choice over other extraction methods. Ionic interactions at modified silica sorbents are studied with respect to the impact on the isolation and purification of analytes. The interactions are characterized by quantitating absolute recoveries for a variety of analytes under different conditions, and qualitative analysis of analytical interferences. Extractions of ionizable compounds were found to be dependent on a myriad of factors. These factors include sample pH, buffer composition, solution concentration, and elution solvent composition. Selectivities for ionizable analytes can be increased by utilizing ionic interactions, particularly in a mixed-mode operation. The extraction of basic compound compounds is generally robust, while methods for the acidic analytes are more highly dependent on the type of counter-ion. Ion selectivities observed were different than those recorded for polymer-based ion-exchange sorbents. The organization of water in the near surface region of the silica-based sorbents is the reason for the disparity between the two types of materials. The utility of a polymeric polystyrene divinylbenzene sorbent for the analysis of analytes from biological matrices is demonstrated. It was shown that these sorbents can withstand harsh chemical environments that would preclude using a silica-based material. Analysis times were shortened and extraction efficiencies were comparable to the silica materials. The extractions were not as selective as those performed on mixed-mode sorbents however.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectChemistry, Analytical.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorBurke, Michael F.en_US
dc.identifier.proquest9906524en_US
dc.identifier.bibrecord.b34563027en_US
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