Although microdialysis (MD) and solid-phase microextraction (SPME) are widely used sampling techniques, a comparison study has not been performed to date. The goal of the research presented was not only to address this issue but also to develop new analytical methods that were more suitable for in vivo study using MD and SPME. A new calibration method called kinetic microdialysis was developed for in vivo sampling. Two MD probes with different flow rates were simultaneously inserted into the symmetric parts of sampling system. A simple empirical equation was proposed to calculate the analyte concentrations in the sample matrix using two different dialysate concentrations. Several factors that influenced the correction factor in this equation were discussed. An excellent correlation was observed between the calculated and theoretical value. This method was subsequently applied for in vivo sampling, for the measurement of pesticide allocation in the different leaves of a jade plant (Crassula ovata). Compared to the other reported MD calibration methods, this novel approach offers several advantages including simplicity, speed, robustness, and increased accuracy. The on-fiber standardization technique for solid-coated SPME was studied and a theoretical model is proposed for the isotropic behavior of adsorption and desorption, based on Fick’s law of diffusion and the Langmuir model. The isotropy of the adsorption and desorption of analytes onto and from the surface of porous solid SPME fiber was validated with the use of a commercially available fiber, a 50 um carbowax/templated resin (CW/TPR) for carbamate pesticide analysis in various in vitro sample matrices. Time constants were comparable for the adsorption and desorption processes. Equilibrium constants and fiber capacities were calculated with the Langmuir Isotherm Model. A kinetic method was developed to calibrate adsorption using desorption. This calibration corrected for the sample matrix effects and minimized displacement effects as a pre-equilibrium extraction. The technique was successfully applied to the analysis of pesticides in river water and white wine. This developed method could be potentially applied for in vivo study. A new kinetic calibration was developed using dominant pre-equilibrium desorption by SPME. The calibration was based on isotropism between absorption and desorption, which was proved theoretically and experimentally in an aqueous solution and semi-solid matrix. This approach allows for the calibration of absorption using desorption to compensate for matrix effects. Moreover, concentration profiles are initially proposed to verify isotropism between the absorption and desorption, while providing a linear approach to obtain time constants for the purpose of quantitative analysis. This linear approach is more convenient, robust and accurate than the non-linear version with the previously used time profiles. Furthermore, the target analytes are used as the internal standards, thus radioactive or deuterated internal standards are not necessary. In addition, dominant pre-equilibrium desorption utilizes the pre-equilibrium approach and offers a shorter sample preparation time, which is typically suitable for in vivo sampling. This kinetic calibration method was successfully applied to prepare samples of polycyclic aromatic hydrocarbons (PAHs) in a flow-through system and in vivo pesticide sampling in a jade plant (Crassula ovata). Previous field studies utilizing SPME predominantly focused on volatile compounds in air or water. Earlier in vivo sampling studies utilizing SPME were limited to liquid matrices, namely blood. In this study, SPME was developed for in vivo laboratory and field sampling of pharmaceuticals in fish muscle. Pre-equilibrium extraction was used to shorten in vivo sampling time. The use of pre-equilibrium desorption rates are proposed as a means to calibrate pre-equilibrium extractions. Excellent linearity was found between the free concentrations determined by SPME from the muscle of living fish and the waterborne concentrations of several pharmaceuticals. It is also firstly proposed a simple SPME method to determine free and total concentrations simultaneously in a living tissue using the known protein binding value. The utility of in vivo SPME sampling under field conditions was evaluated in wild fish collected from a number of different river locations under varying degrees of influence from municipal wastewater effluents. Diphenhydramine and diltiazem were detected in the muscle of fish downstream of a local wastewater treatment plant. Based on this study, SPME technique has demonstrated several important advantages for laboratory and field in vivo sampling. The development of a rapid, robust, easy to deploy technique which combines sampling, extraction and concentration into one step is a potentially important tool for use in vivo field-based sampling. MD and SPME methods have been developed and compared through in vitro and in vivo study. For in vitro study (juice, milk and orange jelly), both methods offered accurate and precise results (recovery: 88-105% with RSD < 15%) for complex sample matrices by standard addition method. The limits of quantification (LOQs) of the two methods developed were below the tolerance levels in milk set by the United Nations Food and Agriculture Organization (FAO). Compared to MD, the fully automated SPME procedure offered several advantages including high-throughput and more efficient sampling, less labor intensity, and capability for batch analysis. For in vivo study, kinetic calibrations were performed using retrodialysis and in-fiber standardization techniques for MD and SPME, respectively. Quantitative analysis was performed to measure pesticide concentrations in living tissue, i.e., the leaves of a living jade plant (Crassula ovata). Although both techniques provided sampling with minimal perturbation to the system under study, SPME was more sensitive, precise and accurate, suitable for field sampling and had a wider application than MD. It demonstrated that SPME has the potential to replace MD for in vivo study.

This thesis presents enhanced analytical methods developed for complex aqueous sample analysis based on solid phase microextraction (SPME). First, the laboratory evaluation of the kinetic calibration approach in aqueous sample analysis using SPME is discussed. A modified SPME device, Polydimethylsiloxane (PDMS) rod passive sampler, was developed and the kinetic calibration method based on the standard preloaded in the extraction phase was applied to determine the time-weighted average (TWA) concentration of organic pollutants in water. Later, the SPME technique was used to investigate the complex interactions between the organic pollutants and humic organic matter (HOM) present in the aqueous samples. The kinetics of the SPME approach in complex aqueous samples was studied. The concentration of freely dissolved analytes and the total concentration of the target analytes in the sample matrix were determined by SPME sampling. The usefulness of the SPME approach for binding studies was further demonstrated by determining the sorption coefficient, a useful parameter for studying the bioavailability of the organic pollutants in the environment. In addition, the commercial Computational Fluid Dynamics (CFD) software COMSOL Multiphysics was used to predict the kinetics of analyte extraction and flow pattern under different experimental conditions using the SPME technique. A good agreement between the prediction and the experimental data confirms the advantages of the CFD application for experimental optimization thus minimizing the need of extensive experiments.

Solid phase microextraction (SPME) has gained much popularity for in vivo applications recently. Thus far, there are two types of pre-equilibrium kinetic calibration that have been applied to in vivo SPME: on-fibre standardization and dominant pre-equilibrium desorption. Both of these techniques have their own advantages and disadvantages. To address the limitations presented by these two techniques, a third pre-equilibrium kinetic calibration method, the diffusion-based interface model, was investigated. The diffusion-based interface model had been successfully applied to air and water samples but was never utilized for in vivo SPME studies. For the first part of the research, on-fibre standardization, dominant pre-equilibrium desorption, and diffusion-based interface model were compared in terms of accuracy, precision, and experimental procedures, by using a flow-through system. These three kinetic calibrations were further validated by equilibrium SPME extraction and protein-plasma precipitation, a current state-of-the-art sampling method. The potential of diffusion-based interface model was yet again demonstrated in the second part of the research project. This calibration method was applied to comparative pharmacokinetic studies of two drugs, fenoterol and methoxyfenoterol, on 5 rats. To provide a constant sampling rate as required for diffusion-based interface model, a SPME animal sampling autosampler, AccuSampler®, was utilized. It custom-written program allowed the entire SPME sampling procedure excluding insertion and removal of SPME probes to be automated. Furthermore, to validate the results obtained by SPME, the AccuSampler® was programmed to withdraw blood after each SPME sampling time point for conventional method analysis using protein-plasma precipitation. The well correlated data obtained by SPME sampling and the conventional method illustrated the potential of diffusion-based interface model as an excellent choice for future in vivo SPME applications.

Although microdialysis (MD) and solid-phase microextraction (SPME) are widely used sampling techniques, a comparison study has not been performed to date. The goal of the research presented was not only to address this issue but also to develop new analytical methods that were more suitable for in vivo study using MD and SPME. A new calibration method called kinetic microdialysis was developed for in vivo sampling. Two MD probes with different flow rates were simultaneously inserted into the symmetric parts of sampling system. A simple empirical equation was proposed to calculate the analyte concentrations in the sample matrix using two different dialysate concentrations. Several factors that influenced the correction factor in this equation were discussed. An excellent correlation was observed between the calculated and theoretical value. This method was subsequently applied for in vivo sampling, for the measurement of pesticide allocation in the different leaves of a jade plant (Crassula ovata). Compared to the other reported MD calibration methods, this novel approach offers several advantages including simplicity, speed, robustness, and increased accuracy. The on-fiber standardization technique for solid-coated SPME was studied and a theoretical model is proposed for the isotropic behavior of adsorption and desorption, based on Fick’s law of diffusion and the Langmuir model. The isotropy of the adsorption and desorption of analytes onto and from the surface of porous solid SPME fiber was validated with the use of a commercially available fiber, a 50 um carbowax/templated resin (CW/TPR) for carbamate pesticide analysis in various in vitro sample matrices. Time constants were comparable for the adsorption and desorption processes. Equilibrium constants and fiber capacities were calculated with the Langmuir Isotherm Model. A kinetic method was developed to calibrate adsorption using desorption. This calibration corrected for the sample matrix effects and minimized displacement effects as a pre-equilibrium extraction. The technique was successfully applied to the analysis of pesticides in river water and white wine. This developed method could be potentially applied for in vivo study. A new kinetic calibration was developed using dominant pre-equilibrium desorption by SPME. The calibration was based on isotropism between absorption and desorption, which was proved theoretically and experimentally in an aqueous solution and semi-solid matrix. This approach allows for the calibration of absorption using desorption to compensate for matrix effects. Moreover, concentration profiles are initially proposed to verify isotropism between the absorption and desorption, while providing a linear approach to obtain time constants for the purpose of quantitative analysis. This linear approach is more convenient, robust and accurate than the non-linear version with the previously used time profiles. Furthermore, the target analytes are used as the internal standards, thus radioactive or deuterated internal standards are not necessary. In addition, dominant pre-equilibrium desorption utilizes the pre-equilibrium approach and offers a shorter sample preparation time, which is typically suitable for in vivo sampling. This kinetic calibration method was successfully applied to prepare samples of polycyclic aromatic hydrocarbons (PAHs) in a flow-through system and in vivo pesticide sampling in a jade plant (Crassula ovata). Previous field studies utilizing SPME predominantly focused on volatile compounds in air or water. Earlier in vivo sampling studies utilizing SPME were limited to liquid matrices, namely blood. In this study, SPME was developed for in vivo laboratory and field sampling of pharmaceuticals in fish muscle. Pre-equilibrium extraction was used to shorten in vivo sampling time. The use of pre-equilibrium desorption rates are proposed as a means to calibrate pre-equilibrium extractions. Excellent linearity was found between the free concentrations determined by SPME from the muscle of living fish and the waterborne concentrations of several pharmaceuticals. It is also firstly proposed a simple SPME method to determine free and total concentrations simultaneously in a living tissue using the known protein binding value. The utility of in vivo SPME sampling under field conditions was evaluated in wild fish collected from a number of different river locations under varying degrees of influence from municipal wastewater effluents. Diphenhydramine and diltiazem were detected in the muscle of fish downstream of a local wastewater treatment plant. Based on this study, SPME technique has demonstrated several important advantages for laboratory and field in vivo sampling. The development of a rapid, robust, easy to deploy technique which combines sampling, extraction and concentration into one step is a potentially important tool for use in vivo field-based sampling. MD and SPME methods have been developed and compared through in vitro and in vivo study. For in vitro study (juice, milk and orange jelly), both methods offered accurate and precise results (recovery: 88-105% with RSD < 15%) for complex sample matrices by standard addition method. The limits of quantification (LOQs) of the two methods developed were below the tolerance levels in milk set by the United Nations Food and Agriculture Organization (FAO). Compared to MD, the fully automated SPME procedure offered several advantages including high-throughput and more efficient sampling, less labor intensity, and capability for batch analysis. For in vivo study, kinetic calibrations were performed using retrodialysis and in-fiber standardization techniques for MD and SPME, respectively. Quantitative analysis was performed to measure pesticide concentrations in living tissue, i.e., the leaves of a living jade plant (Crassula ovata). Although both techniques provided sampling with minimal perturbation to the system under study, SPME was more sensitive, precise and accurate, suitable for field sampling and had a wider application than MD. It demonstrated that SPME has the potential to replace MD for in vivo study.

This thesis presents enhanced analytical methods developed for complex aqueous sample analysis based on solid phase microextraction (SPME). First, the laboratory evaluation of the kinetic calibration approach in aqueous sample analysis using SPME is discussed. A modified SPME device, Polydimethylsiloxane (PDMS) rod passive sampler, was developed and the kinetic calibration method based on the standard preloaded in the extraction phase was applied to determine the time-weighted average (TWA) concentration of organic pollutants in water. Later, the SPME technique was used to investigate the complex interactions between the organic pollutants and humic organic matter (HOM) present in the aqueous samples. The kinetics of the SPME approach in complex aqueous samples was studied. The concentration of freely dissolved analytes and the total concentration of the target analytes in the sample matrix were determined by SPME sampling. The usefulness of the SPME approach for binding studies was further demonstrated by determining the sorption coefficient, a useful parameter for studying the bioavailability of the organic pollutants in the environment. In addition, the commercial Computational Fluid Dynamics (CFD) software COMSOL Multiphysics was used to predict the kinetics of analyte extraction and flow pattern under different experimental conditions using the SPME technique. A good agreement between the prediction and the experimental data confirms the advantages of the CFD application for experimental optimization thus minimizing the need of extensive experiments.

Solid phase microextraction (SPME) has gained much popularity for in vivo applications recently. Thus far, there are two types of pre-equilibrium kinetic calibration that have been applied to in vivo SPME: on-fibre standardization and dominant pre-equilibrium desorption. Both of these techniques have their own advantages and disadvantages. To address the limitations presented by these two techniques, a third pre-equilibrium kinetic calibration method, the diffusion-based interface model, was investigated. The diffusion-based interface model had been successfully applied to air and water samples but was never utilized for in vivo SPME studies. For the first part of the research, on-fibre standardization, dominant pre-equilibrium desorption, and diffusion-based interface model were compared in terms of accuracy, precision, and experimental procedures, by using a flow-through system. These three kinetic calibrations were further validated by equilibrium SPME extraction and protein-plasma precipitation, a current state-of-the-art sampling method. The potential of diffusion-based interface model was yet again demonstrated in the second part of the research project. This calibration method was applied to comparative pharmacokinetic studies of two drugs, fenoterol and methoxyfenoterol, on 5 rats. To provide a constant sampling rate as required for diffusion-based interface model, a SPME animal sampling autosampler, AccuSampler®, was utilized. It custom-written program allowed the entire SPME sampling procedure excluding insertion and removal of SPME probes to be automated. Furthermore, to validate the results obtained by SPME, the AccuSampler® was programmed to withdraw blood after each SPME sampling time point for conventional method analysis using protein-plasma precipitation. The well correlated data obtained by SPME sampling and the conventional method illustrated the potential of diffusion-based interface model as an excellent choice for future in vivo SPME applications.

By means of molecular simulation, we propose possible packing models for £\ and £\¡¬ phases in poly(9,9-di-n-hexyl-2,7-fluorene) (PFH). Simulated multi-chain unit cell structures are compared with experimental diffraction patterns of PFH where the unit cell structure (and the space group) of the high-temperature £\ crystals was identified as monoclinic (C2) and that of £\¡¬ phase (kinetically favored upon programmed cooling) triclinic (P1). Results show that £\ phase prefers to adopt bi-radial side-chain conformation whereas the £\¡¬ phase prefers tetra-radial one. Both models exhibit embracing behavior between adjacent chains in spite of differences in inter-chain distance. A group of embracing chains aligned along b-axis in £\ phase and the comparatively greater inter-chain distance in £\¡¬ phase are consistent with the observed faceting along (100) planes and the tensile cracking along the a-axis. A qualitative analysis of co-existing £\ and £\¡¬ phases reproduce the [001] SAED pattern quite well. In addition, we also show that arbitrary alternation of 40o and 140o in dihedral angle between neighboring monomers generates equally stable single-chain conformations in this case of linear alkyl side-chains.

Thesis (Ph. D.)--Miami University, Dept. of Chemistry and Biochemistry, 2003. / Title from first page of PDF document. Document formatted into pages; contains xvi, 254 p. : ill. Includes bibliographical references.

Solid phase organic synthesis is a powerful technique to facilitate rapid synthesis and easy purification of organic compounds. The advancement of linkers and cleavage strategies is of paramount importance for the success of this approach. This thesis is concerned with the development of a robust safety catch linker system aimed to allow a broad range of commonly used reagents to be employed in a synthetic sequence carried out on a solid support. Chapter 1 outlines the principles of solid phase organic synthesis, the terminology associated with this approach and the advantages and disadvantages compared to conventional solution phase methods. Common attachment and release strategies for various functional groups are described and the safety catch principle is introduced. Chapter 2 discusses the design features of the linker system. Proof of principle is demonstrated for the attachment and release strategies with a simple solution phase model system. Chapter 3 describes the adaptation of the linker system to the solid phase. Key transformations are modelled with solution phase experiments and subsequently applied to solid phase. The loading determination of the solid phase system is also described. Chapter 4 reports an assessment of the reactivity of the linker system in the coupling transformation of aliphatic alcohols and amines. The chemoselectivity and efficiency of the CAN debenzylation/cyclorelease protocol is also evaluated. Chapter 5 demonstrates the utility of the linker system with the optimisation of a simple synthetic sequence in solution followed by adaptation to the solid phase. The synthesis of a pilot library of aryl alcohols utilizing a Suzuki coupling on solid support is described. The attachment and release of amines is also demonstrated with solid phase examples. Chapter 6 examines the potential of the linker system as an analytical tool to assess the outcome of stereoselective transformations. A chiral auxiliary is attached to the solid phase by aid of the safety catch linker and released into solution. A solution phase model system is developed to aid preliminary investigations in solution prior to adaptation to the solid phase.

Thesis (Ph. D.)--Ohio State University, 2007. / Full text release at OhioLINK's ETD Center delayed at author's request