Cette thèse s’est inscrite dans le cadre du projet ACACIA (Amélioration du CAptage du CO2 Industriel et Anthropique) soutenue par le pôle de compétitivité AXELERA et financé par « FUI » et « LE GRAND LYON ». Notre objectif était d’immobiliser l’anhydrase carbonique dans des gels inorganiques, en particulier la silice afin de préserver la structure de l’enzyme, sa fonctionnalité et de la protéger de l’environnement physico-chimique environnant. Pour cela, des essais préliminaires simples nous ont permis d’élaborer et de construire une cellule, comprenant membrane polymérique poreuse imprégnée de solution enzymatique aqueuse, ou de gel de silice lui-même imprégné de solution aqueuse d’enzyme. A partir de ce montage, nous avons étudié des paramètres importants de la membrane, comprenant un tampon, sa nature, molarité et son pH, ainsi que la taille des pores de la membrane et la concentration en enzyme. Il a été trouvé qu’un tampon à base de bicarbonate permet de déplacer l’équilibre de déprotonation du CO2(aq) vers un pH plus élevé, par l’apport des ions HCO3- équilibrés par des cations comme Na+, et favorise une contribution plus importante à la diffusion du CO2 à travers la membrane. Nous avons également observé que quelque soit le gaz de captage (100 % et / ou 10 % de CO2), le tampon et le type de membrane, une perméance maximum a été observée pour une concentration en enzyme de 0.2 mg mL-1. / This thesis was part of the ACACIA project on the Improvement of CO2 capture from industrial and anthropogenic fumes, supported by the AXELERA and funded by « FUI » et « THE GRAND LYON ». Our goal was to immobilize the carbonic anhydrase in inorganic gels, particularly silica, in order to preserve the structure of the enzyme, its functionality and protection of the physico-chemical environment. For this, simple preliminary tests have allowed us to develop a cell comprising a porous polymeric membrane impregnated with the aqueous enzyme solution or a silica gel itself impregnated with the enzyme solution. Important parameters were then studied on this cell, comprising the buffer: its nature, molarity and pH, the membrane pore size, and the enzyme concentration. It was found that a bicarbonate-based buffer displaced the deprotonation equilibrium of CO2(aq) to a higher pH, due the contribution of HCO3- balanced by cations such as Na+, and promotes a greater contribution to the CO2 diffusion across the membrane. We also observed that whatever the gas (100 % and / or 10 % CO2), the buffer and the type of membrane, a maximum permeance was observed for an enzyme concentration of 0.2 mg mL-1.

El glifosat, N-(fosfonometil) glicina, és un dels herbicides més utilitzats arreu del món a causa de la seva baixa toxicitat i al seu ampli espectre d'aplicació. A conseqüència del gran ús que se'n fa, és necessari monitoritzar aquest compost i el seu principal metabòlit, l'àcid aminometilfosfònic (AMPA), en el medi ambient. S'han descrit diversos mètodes instrumentals basats en cromatografia de gasos (GC) i de líquids (HPLC), sent aquesta darrera l'opció més favorable a causa del caràcter polar dels anàlits. Per assolir nivells de concentració baixos cal, però, la preconcentració dels anàlits.En aquest treball s'estudien diferents alternatives amb aquest objectiu. S'ha avaluat la tècnica de membrana líquida suportada (SLM) on la membrana consisteix en una dissolució orgànica, que conté un transportador (en el nostre cas, un bescanviador d'anions comercial, Aliquat 336), que impregna un suport polimèric microporós que se situa entre dues solucions aquoses: la de càrrega, que conté els anàlits inicialment, i la receptora, on es retenen els anàlits després del seu transport a través de la membrana. Les condicions d'extracció més adequades s'obtenen treballant en medi bàsic amb NaOH on els anàlits estan en forma aniònica i les majors recuperacions s'obtenen amb HCl 0,1 M o NaCl 0,5 M, la qual cosa indica que l'ió clorur és la força impulsora del transport.Un cop dissenyat el sistema, es duen a terme experiments de preconcentració amb dues geometries diferents: un sistema de membrana laminar (LSLM) on recircula la fase receptora i un sistema de fibra buida (HFSLM). Els millors resultats s'obtenen amb el mòdul de fibra buida, amb factors de concentració de 25 i 3 per a glifosat i AMPA, respectivament, fent recircular durant 24 hores 100 ml de solució de càrrega i 4 ml de solució receptora. També s'aplica una tècnica més selectiva, la cromatografia d'afinitat amb ió metàl·lic immobilitzat (IMAC), basada en la interacció entre els anàlits i un metall immobilitzat en una resina a través d'un grup funcional d'aquesta. En aquest estudi s'immobilitza pal·ladi al grup funcional 8-hidroxiquinoleïna de la resina amb matriu acrílica Spheron Oxine 1000 i s'avalua per a l'extracció i preconcentració de glifosat i AMPA. Per a ambdós anàlits l'adsorció és del 100 % i les recuperacions són superiors al 80 % i al 60 % per a glifosat i AMPA, respectivament, utilitzant HCl 0,1 M + NaCl 1 M com a eluent. Aquests resultats es comparen amb els obtinguts amb dues resines més, també carregades amb pal·ladi: Iontosorb Oxin 100, que té el mateix grup funcional però matriu de cel·lulosa, i Spheron Thiol 1000, on el grup funcional és un tiol i la matriu també és acrílica. Per al glifosat els resultats són similars amb totes les resines, però per a l'AMPA la resina Spheron Thiol és la única que proporciona recuperacions superiors al 93 %.Finalment, una altra opció estudiada és l'acoblament de dues columnes de cromatografia líquida (LC-LC). En l'estudi l'objectiu és millorar el mètode existent per a glifosat i AMPA en aigües naturals on el LOD era de 0,25 ug/l. El mètode consisteix en la derivatització precolumna amb el reactiu fluorescent FMOC i l'anàlisi amb l'acoblament LC-LC-fluorescència. Variant lleugerament les condicions de derivatització s'aconsegueix quantificar 0,1 ug/l de glifosat i AMPA. Es fortifiquen aigües naturals amb 0,1, 1 i 10 ug/l dels anàlits per validar el mètode. S'obtenen recuperacions d'entre el 85 % i el 100 %, amb desviacions estàndard relatives inferiors al 8 %. Aplicant una tècnica de preconcentració prèvia a la derivatització i anàlisi utilitzant una resina de bescanvi aniònic, Amberlite IRA-900, es millora la sensibilitat del mètode i s'assoleix un LOD per al glifosat de 0,02 ug/l. / Glyphosate, N-(phosphonomethyl)glycine, is one of the most widely used herbicides in the world due to its low mammal toxicity. Therefore, there is a great interest in the monitoring of this compound and its major metabolite aminomethylphosphonic acid (AMPA), in environmental matrices. A great variety of methods based on gas chromatography (GC) and liquid chromatography (HPLC) have been applied for their determination. HPLC is the most popular option due to the polar nature of both compounds. However, the analysis of these compounds at residue levels requires the use of preconcentration techniques.In this work we have studied different alternatives to this aim. We have evaluated the supported liquid membrane (SLM) technique where the membrane consists of an organic solution, which contains the carrier (in this case a commercial anion exchanger extractant, Aliquat 336), that impregnates a microporous polymeric support placed between two aqueous solutions: the feed solution, which initially contains the analytes, and the stripping solution, where the analytes are retained after their transport through the membrane. The best conditions were achieved with NaOH as feed solution, where the analytes are present in their anionic form and 0.1 M HCl or 0.5 M NaCl as stripping solutions indicating that the chloride ion is the responsible for the transport.Under these chemical conditions some preconcentration experiments were run using two different geometries of the membrane: a laminar membrane system (LSLM) where the stripping solution can be recirculated and a hollow fiber liquid membrane (HFSLM). The best results were obtained for the liquid membrane system in HF configuration, with concentration factors of 25 and 3 for glyphosate and AMPA, respectively, after recirculation during 24 hours of 100 ml of feed solution and 4 ml of stripping solution.A more selective technique is also studied, immobilised metal ion affinity chromatography (IMAC), which is based on the interaction between the analytes and a metal immobilised in a resin through a functional group. In this work we have immobilised palladium through the chelating group 8-hydroxyquinoline of the acrylic resin Spheron Oxine and it has been evaluated for the preconcentration of glyphosate and AMPA. 100 % adsorption has been obtained for both analytes and the recoveries are higher than 80 % and 60 % for glyphosate and AMPA, respectively, using 0.1 M HCl + 1 M NaCl as eluent. These results are compared with the results obtained working with two different resins also charged with palladium: Iontosorb Oxin, which has the same functional group but cellulose matrix, and Spheron Thiol, which a thiol functional group and acrylic matrix. The results for glyphosate are similar with all the resins tested, but for AMPA the best results are obtained with Spheron Thiol with recoveries higher than 93 %.Finally, another option studied is the coupling of two liquid chromatographic columns (LC-LC). In this work the objective is to improve the existing method for the analysis of glyphosate and AMPA in natural waters which had a LOD of 0.25 mg/l. The method consists of the pre-column derivatization with the fluorescent reagent FMOC and the analysis by LC-LC-fluorescence detection. The derivatization step has been slightly modified with the aim of decreasing the limits of quantification of glyphosate and AMPA down to 0.1 mg/l. Different water samples spiked at three concentration levels (0.1, 1, 10 mg/l) were analysed by the improved method yielding recoveries between 85-100 % with relative standard deviations lower than 8 %.Additionally, the potential of an anion-exchange resin, Amberlite IRA-900, for preconcentration of glyphosate, previously to the derivatization step, has been investigated. In this way the LOD of the parent compound has been lowered to 0.02 mg/l.

Bioanalytical chemistry is a challenging field, often involving complex samples, such as blood, plasma, serum or urine. In many applications, sample cleanup is the most demanding and time-consuming step. In the work underlying this thesis a novel dynamic miniature extractor, known as a hollow-fibre liquid-phase microextractor (HF-LPME), was designed, evaluated and studied closely when used to clean plasma samples. Aqueous-organic-aqueous liquid extraction, in which the organic liquid is immobilised in a porous polypropylene membrane, was the principle upon which the extractor was based, and this is discussed in all the papers associated with this thesis. This type of extraction is known as supported-liquid membrane extraction (SLM). The aim of this work was the development of a dynamic system for SLM. It was essential that the system could handle small sample volumes and had the potential for hyphenations and on-line connections to, for instance, LC/electrospray-MS. The design of a miniaturised HF-LPME device is presented in Paper I. The extraction method was developed for some weakly acidic pesticides and these were also used for evaluation. In the work described in Paper II, the method was optimised on the basis of an experimental design using spiked human plasma samples. Paper III presents a detailed study of the mass-transfer over the liquid membrane. The diffusion through the membrane pores was illustrated by a computer-simulation. Not surprisingly, the more lipophilic, the greater the retention of the compounds, as a result of dispersive forces. The main focus of the work described in Paper IV was to make the HF/LPME system more versatile and user-friendly; therefore, the extractor was automated by hyphenation to a SIA system. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript.

Ce travail se situe dans le cadre des recherches du laboratoire sur un procédé d’extraction et desextraction, qui implique trois phases liquides, deux phases aqueuses et une phase organique. La faisabilité d’un tel procédé passe par le choix de la phase organique et par l’étude des équilibres mis en jeu lors du processus d’extraction.Le principal objectif concerne : la récupération et la concentration de phénol contenu dans une solution aqueuse, en utilisant un pertracteur à disques tournants alternatifs en régime batch, semi-batch et continu. Par un mécanisme du transfert de matière entre les phases, le phénol passe de la phase aqueuse d’alimentation vers la phase organique puis de la phase organique vers la phase aqueuse réceptrice.La faisabilité de la méthode est testée en mode fermé. Nous étudions l’influence de certains paramètres : tels que la concentration du phénol, la variation de pH de la phase d’alimentation, la vitesse de rotation des disques et le volume de la phase organique, sur l’évolution du transfert du phénol entre les phases. Une solution aqueuse à pH 2, ayant une concentration en phénol égale à 50, 100 ou 300 mg.L-1, est mise en contact avec de l’huile de colza, qui est elle-même en contact avec une solution aqueuse à pH 13. Les résultats montrent qu’au bout de six heures de fonctionnement, 70% à 99% du phénol contenu initialement dans la solution aqueuse à pH 2, se trouve dans la phase aqueuse à pH 13.Afin de récupérer et de concentrer le phénol dans la phase réceptrice, nous avons réalisé des expériences dans le pertracteur fonctionnant en mode semi-ouvert et en mode ouvert.En système semi-ouvert, l’influence de trois paramètres est étudiée : la concentration initiale de phénol, la vitesse de rotation des disques et le débit de la phase d’alimentation. En système ouvert, seul l’influence du débit à la phase aqueuse est analysée. Enfin, grâce à la modélisation basée sur la théorie du double film, nous avons estimé l’ordre de grandeur des coefficients de transferts de matière partiels pour différentes vitesses de rotation en système fermé. / This work is focused on a pertraction process, coupling extraction and stripping steps in the same apparatus and involving three liquid phases, two aqueous phases and one organic phase. The process feasibility requires the choice of a appropriate organic phase (membrane) and a phase equilibria studies.The main objective was recovery and concentration of phenol contained in dilute aqueous solutions using a rotating discs pertractor in batch, semi-batch and continuous mode. The phenol is transferred from the feed phase (aqueous phase) through the membrane (organic phase) in the receiving phase (aqueous phase).The feasibility of the method is tested in a batch system. We studied the influence of some parameters such as the phenol concentration, the feed pH, the discs rotational speed and the volume of the organic phase. An aqueous solution at pH 2 (feed) with a phenol concentration equal to 50, 100 and 300 mg.L-1, is placed in contact with rapeseed oil (liquid membrane), that is itself in contact with an aqueous solution at pH 13 (receiving phase). The obtained results show that after 6 hours, 70% to 99% of phenol initially contained in the aqueous solution at pH 2, is transferred in the aqueous phase at pH 13.To concentrate phenol in the receiving phase, we performed experiments in semi-batch and continuous mode.In semi-batch system, the influence of three parameters is studied: the feed concentration, the discs rotation speed and the feed flowrate. In open system, (continuous mode), only the influence of the aqueous phases flowrates is analyzed.Finally, using mass transfer model based on a double film theory, we estimate the partial mass transfer coefficients for three phases at different rotation speeds in batch system.

In dieser Arbeit werden verschiedene Verfahren vorgestellt, um Saturnpartikel herzustellen. Es wird die Selbstanordnung von erfolgreich hergestellten Saturnpartikeln untersucht. Im ersten Teil werden durch ein äquatoriales Ätzverfahren Saturnpartikel mit hydrophoben Kappen sowie einem hydrophilen Gürtel aus hydrophob beschichteten sphärischen Partikeln hergestellt. Mit einer Monolage dieser Saturnpartikel können Membranen aus Wasser (sogenannte Pickering-Membranen) stabilisiert werden. Die Pickering-Membranen sind über einen Zeitraum von mehreren Tagen stabil und lassen Permeabilitätsuntersuchungen zu. Diese Pickering-Membranen können als ein Spezialfall einer Supported Liquid Membrane angesehen werden. Es werden die Permeabilitätsunterschiede von Kohlenstoffdioxid gegen Luft sowie Luft gegen Schwefelhexafluorid betrachtet. Die resultierenden Werte stimmen in zufriedenstellender Weise mit theoretisch – nach dem für Supported Liquid Membranes gängigen Löslichkeits-Diffusionsmodell – berechneten Werten überein. Im zweiten Teil werden Partikel über Float-casting in Membranen eingebettet und dadurch rundherum – nicht jedoch an den Polkappen – äquatorial maskiert. Anschließend wird Gold aufgedampft und die maskierende Membran entfernt, sodass Saturnpartikel zurück bleiben. Die Saturnpartikel weisen hydrophile Kappen sowie einen hydrophoben Gürtel auf. An einer Öl-Wasser-Grenzfläche kommt es zu einer Selbstanordnung dieser Saturnpartikel durch Verknüpfung ihrer Gürtel in Form von zweidimensionalen Netzwerken. In diesen Netzwerken können einfache geometrische Formen gefunden werden. Es ist dabei nicht möglich, die Partikel durch einen Krafteintrag in einem flächendeckenden Muster zu organisieren. Die Untersuchung erfolgt durch konfokale Fluoreszenzspektroskopie. Die Goldkappen der Saturnpartikel zeigen ein Fluoreszenzsignal.:Bibliographische Beschreibung und Referat Danksagung Inhaltsverzeichnis Abkürzungsverzeichnis 1 Einleitung 2 Theoretischer Teil 2.1 Januspartikel 2.1.1 Herstellungsmöglichkeiten 2.1.1.1 Herstellung durch Oberflächenmodifizierung 2.1.1.2 Phasenseparation zweier nicht mischbarer Flüssigkeiten 2.1.1.3 Herstellung aus Bausteinen über Selbstanordnung 2.1.2 Anwendung 2.2 Saturnpartikel 2.2.1 Herstellung durch Oberflächenmodifizierung 2.2.2 Herstellung durch Phasenseparation von nicht mischbaren Flüssigkeiten 2.2.3 Herstellung aus Bausteinen über Selbstanordnung 2.3 Partikelstabilisierte Membranen 2.4 Aktuelle Fortschritte in der Gastrennung Mittels Gestützter Flüssigmembranen 2.4.1 Gestützte Flüssigmembranen (Supported Liquid Membranes) 2.4.2 Flüssigkeiten 2.4.2.1 Nicht-Ionische Flüssigkeiten 2.4.2.2 Ionische Flüssigkeiten 2.4.2.3 Stark Eutektische Lösemittel 2.4.3 Matrixmaterialien 2.4.4 Träger 2.4.5 Trennaufgaben 2.4.5.1 CO2/N2 2.4.5.2 CO2/CH4 2.4.5.3 Alken/Alkan 2.4.5.4 Andere Trennaufgaben 2.4.6 Einfluss von Temperatur und Druck 2.4.7 Stabilität 2.4.8 Simulationen 2.4.9 Zusammenfassung und Ausblick des Kapitels 2.5 Grenzflächen 2.5.1 Grenzflächenspannung 2.5.2 Kontaktwinkel und Benetzung 2.5.3 Partikelassistierte Benetzung 2.5.3.1 Float-casting 2.6 Modifizierung von Oberflächen durch Selbstorganisierende Monoschichten 2.6.1 Silanisierung von Oberflächen 2.6.2 Thiolisierung von Oberflächen 2.7 Fluoreszenz 2.8 Netzwerkanalyse 3 Ergebnisse und Diskussion 3.1 Herstellung von Saturnpartikeln durch schrittweises Einsinken in ein Polymer 3.2 Herstellung von Saturnpartikeln mit geätztem Ring mit Ätzzelle 3.2.1 Beschreibung der Ätzzelle 3.2.2 Optimierung des Verfahrens 3.2.2.1 Einlegen der Thermoplastischen Folien in Ethanol 3.2.2.2 Einführung eines Luer-Lock-Systems 3.2.2.3 Erhöhung der Pumpgeschwindigkeit bei der Reinigung 3.2.3 Beschreibung der erhaltenen Saturnpartikel 3.3 Pickering-Membranen stabilisiert durch Saturnpartikel mit geätztem Ring 3.3.1 Permeabilitätsuntersuchungen von Pickering-Membranen 3.3.1.1 Theoretische Permeanzen 3.3.1.2 Experimentelle Permeanzen 3.4 Herstellung von Saturnpartikeln durch Beschichtung mit Gold und graduelles Ätzen 3.5 Herstellung von Saturnpartikeln über Float-casting 3.5.1 Herstellung von Saturnpartikeln über Float-casting: Glaspartikel 3.5.2 Herstellung von Saturnpartikeln über Float-casting: Siliziumdioxidpartikel 3.5.3 Herstellung von Saturnpartikeln über Float-casting: Silsesquioxanpartikel 3.5.3.1 Bestimmung der Schichtdicke des Goldes 3.5.3.2 Membranherstellung mit Silsesquioxanpartikel über Floatcasting 3.5.3.3 Oberflächenmodifizierung der Goldkappen 3.6 Selbstanordnung von Saturnpartikeln unter dem Konfokalmikroskop 3.6.1 Erste Anordnungen 3.6.2 Einsatz von Zinkbromidlösungen 3.6.3 Fluoreszenz von Saturnpartikeln bei verschiedenen Flüssigkeitsgemischen 3.6.4 Fluoreszenz der Goldkappen 3.6.5 Flüssigkeitsmeniskus in den Probengefäßen 3.6.6 Messung an der Flüssig-Flüssig-Grenzfläche 3.6.7 Schallunterstützte Anordnung 3.6.8 Mathematische Beschreibung der Saturnpartikelnetzwerke 4 Zusammenfassung und Ausblick 5 Experimenteller Teil 5.1 Eingesetzte Chemikalien 5.2 Verwendete Geräte 5.3 Partikelsynthese und -oberflächenmodifikation 5.3.1 Herstellung von Siliziumdioxidpartikeln im Submikrometermaßstab 5.3.2 Herstellung von Polystyrolpartikeln im Mikrometermaßstab 5.3.3 Oberflächenmodifizierung von Glaspartikeln mit Silanen 5.4 Saturnpartikel durch schrittweises Einsinken in ein Polymer 5.5 Saturnpartikel durch Beschichtung mit Gold und graduelles Ätzen 5.6 Saturnpartikel mit geätztem Ring mit Ätzzelle 5.6.1 Pickering-Membranen in einem Rollrandgläschen 5.6.2 Pickering-Membranen in der Permeationsapparatur und Permeationsuntersuchungen 5.7 Saturnpartikeln über Float-Casting 5.7.1 Glaspartikel, Supelco Glass Beads 5.7.2 Siliziumdioxidpartikel, Stöberpartikel 5.7.3 Silsesquioxanpartikel, Tospearls 5.8 Kontaktwinkelmessungen 5.8.1 Kontaktwinkel von Partikeln 5.8.2 Kontaktwinkel von planaren Substraten 5.9 Konfokalmikroskopieaufnahmen 5.9.1 Fluoreszenzlösungen 5.9.2 Konfokalmikroskopieprobengefäße 5.9.3 Subwoofer 5.9.4 Messungen am Konfokalmikroskop 5.10 Rasterelektronenmikroskopieaufnahmen 5.11 Plasmaätzen Literaturverzeichnis Selbstständigkeitserklärung Lebenslauf Veröffentlichungen und Tagungsbeiträge

This thesis focuses on low-cost microextraction techniques and their application for purification and preconcentration of biological samples, specifically on the experimental study of supported liquid membrane (SLM) extraction. The described microextraction technique uses commercially available filtration plates as the extraction units and allows the extraction of basic drugs from biological samples of urine and blood (in the form of dried blood spots). The experimental part includes the optimization of microextraction conditions of basic drugs from real samples through a SLM coupled in-line to lab-made capillary electrophoresis. The basic optimization of microextraction conditions involved selecting the appropriate organic phase for membrane impregnation (1:1 mixture of ENB and DHE), appropriate agitation speed for sample convection during extraction (1000 rpm), and optimal ratio of donor to acceptor volumes for high preconcentration of the analytes (400:15 µL). After basic optimization, the effect of donor alkalization with NaOH on extraction recovery (ER) was investigated. For all matrices used (saline solution, undiluted human urine samples, human capillary blood eluted from dry blood spots with deionized water), the highest ER values were achieved using a neutral donor and an acidic acceptor. The extraction time (60 minutes) was optimized based on the time profile of the microextraction for 120 minutes. This optimized microextraction method is suitable for the determination of basic drugs in real matrices with sufficient sample clean-up, preconcentration and ER values.

Membrane transport processes underlie many purification technologies. The efficiency of a membrane separation process depends upon material throughput (flux), and the degree to which the membrane discriminates amongst species in the feed stock (selectivity). In a supported liquid membrane, flux may be enhanced by carrier molecules, which act as catalysts of translocation. Carrier molecules also confer selectivity, via differential molecular recognition of the substances in the feed stock. The effect of electrical potential on the flux and selectivity of carrier-containing supported liquid membranes is not well documented. We elected to study the effect of electrical potential on supported liquid membranes containing valinomycin, a potassium ionophore, and a calixarene ester, a sodium ionophore. In these systems, the open circuit membrane potential could be made positive or negative by the choice of anion. With both of these carriers, we observed that selectivity for potassium or sodium salts was dependent on the open circuit membrane potential. To confirm that electrical potential was responsible for the observed selectivity variance, we applied a potential across the membrane using a potentiostat. The applied potential created conditions for carrier-mediated electrodialysis, where oxidation and reduction reactions on either side of the membrane act as the driving force for transmembrane flux of charged species. In chronoamperometry experiments, we found that selectivity for potassium or sodium ion was dependent on the applied electrical potential. Subject to some constraints, selectivity and flux could be controlled by the application of positive or negative electrical potentials. Linear sweep voltammetry experiments allowed for the rapid prediction of the potential that must be applied to achieve optimal selectivity. We also found that membrane potential measurements, as well as the magnitude of current that flows in chronoamperometry experiments, could be interpreted to predict Eisenman and Hofmeister sequences. These results are novel, and await a convincing theoretical justification. The results also suggest that a separation technology could be developed around the idea of modulating selectivity with electrical potential. In this regard, carrier-mediated electrodialysis may be suitable for the sequestration of toxic or radioactive heavy metals, and a large number of carrier molecules for metal ions are currently known. The technique may also be suitable for separating organic molecules, such as high-value chiral pharmaceuticals. Supported liquid membranes are a useful research tool, but industrial applications may require a more stable membrane architecture. / Graduate

The presented thesis investigates the transfer of drug molecules across interfaces that mimic biological membrane barriers. The permeability of drug molecules across biological membrane mimics has been investigated in a novel artificial membrane permeation assay configuration using an in situ time-dependent approach and reproducible rotation of the membrane. A method to determine the membrane permeability from the knowledge of measured permeability and the applied stirring rate is presented. The initial transient of the permeation response, previously not observed in situ, is investigated and its importance in data evaluation is discussed. The permeability coefficients of 31 drugs are optimised for the conditions found in vivo and a correlation with the fraction absorbed in humans is presented. The evidence for ionic and/or ion-pair flux across the artificial membrane obtained from measurement of permeability at different pH is supported by the investigation of the permeation assay with external membrane polarisation. The permeability coefficient of the solute's anionic form is determined. Liquid/liquid electrochemistry has been used to study the transfer of ionized species across the interface between water and 1,2-dichloroethane. An alternative method to study the transfer of partially ionised drug molecules employing a rotating liquid/liquid interface is presented. In addition, a bipolar electrochemical cell with a rotating-disc electrode is developed and its properties investigated in order to verify the hydrodynamics of the rotating artificial membrane configuration. Finally, in support of the electrochemical techniques used is this thesis, a detailed preparation and evaluation of the silver/silver sulphate reference electrode is presented.

The thesis presents experimental study on application of various polypropylene membranes (with different thicknesses, porosity and pore size) for direct coupling of membrane microextractions with capillary electrophoresis. No comprehensive study, which describes effect of these membrane parameters on extraction recoveries, was published in the past. Previous scientific works prefer application of 100 µm polypropylene membranes for their easy handling and satisfactory extraction efficiencies. Experimental part includes examination of selected polypropylene membranes as supported liquid membranes in-line coupled to capillary electrophoresis for analysis of basic drugs from complex samples. Membranes with three thicknesses (25, 100 and 170 µm) were tested. The highest extraction recoveries were achieved for the 25µm thick polypropylene membrane. Various pH conditions of donor and acceptor operational solutions were examined for extractions from real complex matrices (urine, plasma). The optimal extraction conditions were 10 mM NaOH as donor phase and 10 mM HCl as acceptor phase. 25µm membranes offer higher extraction recoveries, reduced consumption of organic solvents for membrane impregnation, similar mechanical stability and similar clean-up ability compared to thicker polypropylene membranes.