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In this study, the extraction efficiency of natural deep eutectic solvents (NADES) based on choline chloride as a hydrogen bond acceptor (HBA) and five different hydrogen bond donors (HBD lactic acid, 1,4-butanediol, 1,2-propanediol, fructose and urea) was evaluated for the first time for the isolation of valuable bioactive compounds from Achillea millefolium L. The phytochemical profiles of NADES extracts obtained after ultrasound-assisted extraction were evaluated both spectrophotometrically (total phenolic content (TPC) and antioxidant assays) and chromatographically (UHPLC-MS and HPLC-UV). The results were compared with those obtained with 80% ethanol, 80% methanol, and water. The highest TPC value was found in the lactic acid-based NADES (ChCl-LA), which correlated with the highest antioxidant activity determined by the FRAP analysis. On the other hand, the highest antiradical potential against ABTS$^{+•}$ was determined for urea-based NADES. Phenolic acids (chlorogenic acid and dicaffeoylquinic acid isomers), flavones (luteolin and apigenin), and their corresponding glucosides were determined as the dominant individual phenolic compounds in all extracts. The antibacterial and antifungal properties of the extracts obtained against four bacterial cultures and two yeasts were evaluated using two methods: the agar dilution method to obtain the minimum inhibitory concentration (MIC) and the minimum bactericidal or fungicidal concentration (MBC or MFC), and the disc diffusion method. ChCl-LA had the lowest MIC and MBC/MFC with respect to all microorganisms, with an MIC ranging from 0.05 mg mL$^{−1}$ to 0.8 mg mL$^{−1}$, while the water extract had the weakest inhibitory activity with MIC and MBC/MFC higher than 3.2 mg mL$^{−1}$.

Electrical conductivity measurements on aqueous solutions of the lithium of fullerenehexamalonic acid, ?$T_h-C_{66}(COOLi)_{12}$?, were carried out at four temperatures: 5, 15, 25 and 35 C. The limiting equivalent conductivities of the fullerenehexamalonate anion were estimated at the temperatures of our measurements. Temperature dependence of the molar conductivity of ?$T_h-C_{66}(COOLi)_{12}$? can be satisfactorily explained by changed viscosity of solvent Izmerili smo molske prevodnosti vodnih raztopin litijeve soli fulerenheksamalonske kisline, ?$T_h-C_{66}(COOLi)_{12}$?, pri temperaturah 5, 15, 25 in 35 stopinj C ter v območju koncentracij med približno 0,2 in 0,00014 mol(COO^-)/dm^3. Ocenili smo molske prevodnosti pri neskončnem razredčenju pri vseh štirih temperaturah. Temperaturno odvisnost molske prevodnosti LiFHM je mogoče zadovoljivo pojasniti z vplivom temmperature na viskoznost raztopine. Molske prevodnosti litijevega fulerenheksamalonata smo primerjali z molskimi prevodnostmi natrijevega in kalcijevega fulerenheksamalonata, di smo jih določili že pri prejšnjih raziskavah.

V diplomskem delu sem raziskoval, če okolje in človeška dejavnost kakorkoli vplivata na površinsko napetost naravnih vodotokov. Kot primer, na katerem sem skušal to tematiko preučiti, sem izbral potok Želimeljščico. Vzdolž tega vodotoka sem izbral štiri vzorčevalna mesta, na katerih sem vzorčil vodo iz tega vodotoka ter tem vzorcem določil vrednost površinske napetosti. Za merjenje površinske napetosti sem uporabil tenziometrično metodo z uporabo Wilhelmyjeve ploščice. Dodatno sem izmeril še električno prevodnost teh vzorcev, da bi ugotovil, če v tem primeru obstaja kakšna povezava med obema izmerjenima lastnostima vzorcev. Rezultati na primeru vodotoka Želimeljščica so pokazali, da okolje in človeška dejavnost vplivata na vrednost površinske napetosti naravnih voda. Površinska napetost vode omenjenega vodotoka je bila najvišja pri izviru (73,7 mN/m), hkrati pa je bila tam najvišja tudi specifična prevodnost vode (627 μS/cm). Za opazovani vodotok so meritve pokazale, da površinska napetost pada od izvira proti izlivu, nisem pa uspel nedvoumno odkriti vzroka za ta pojav. In my thesis, I studied whether the environment and human activity have any effect on the surface tension of natural watercourses. As an example, on which I tried to examine this topic, I chose the Želimeljščica stream. Along this watercourse, I selected four sampling points where I sampled water from this watercourse and determined the surface tension value for these samples. I used a tensiometric method using the Wilhelmy plate to measure surface tension. I also measured the electrical conductivity of these samples to see if there was any correlation between the two measured properties. The results of the case of the watercourse Želimeljščica showed that the environment and human activity influence the value of the surface tension of natural waters. The surface tension of the said watercourse was the highest at its source (73,7 mN/m) and this was valid also for the specific conductivity of the water (627 μS/cm). For the observed watercourse, measurements showed that the surface tension was falling from the spring, but I was unable to unequivocally identify the cause of this phenomenon.

V diplomskem delu opisujem sestavne dele iono-selektivnih elektrod in napake, ki se lahko pojavijo pri merjenjih z ionoselektivnimi elektrodami. S pomočjo znanstvenih člankov in literature s področja ionoselektivnih elektrod sem proučeval, kako lahko na neželen odziv instrumenta vplivajo vzorci, ki vsebujejo interferenčne ione ali imajo ekstremne pH-vrednosti. Prikazano je, kakšnim merilom mora ustrezati elektrolitski ključ in kakšen pomen ima le-ta pri odkrivanju merskih napak. Dodatno sem raziskal na kaj moramo biti pozorni pri delu z biološkimi vzorci, zakaj se pojavlja lezenje elektrodnega signala in kako pravilno shranjevati elektrode ter jim na ta način podaljševati življenjsko dobo. Poudarjen je bil tudi pomen previdnosti pri pripravi standardnih raztopin in pozornosti pri uporabi primernega merilnika napetosti. Za vsako izmed opisanih interferenc so bile raziskane in predlagane primerne rešitve. In this work, potential sources of errors when analyzing samples with Ion-Selective Electrodes have been studied. With the help of scientific articles and literature on Ion-Selective Electrodes, it was shown how samples containing interfering ions and/or having extreme pH values can affect the measured values. It was also shown how important is the adequate choice of a salt bridge and how crucial this choice is when systematic errors in measurements need to be identified. It was investigated what should be considered when dealing with biological samples, what is the source of electrode drift and how a proper electrode storage can ensure a long shelf life. Carefulness is emphasized when preparing standard solutions as well as when an adequate measuring instrument has to be chosen. For chosen interferences the procedures helping minimize measurement errors have been investigated and proposed.

Z ionsko izmenjevalno kromatografijo sem v raztopini poli(alilamin hidroklorida) kloridne ione zamenjal s hidroksidnimi in tako pripravil rahlo bazično raztopino polialilamina. Vzorce merjenih raztopin polialilaminskih soli sem pripravil z dodajanjem izbrane količine raztopin različnih kislin v založno raztopino polialilamina. Tako pripravljenim raztopinam izbranih soli (F-, Cl-, Br-, I-, ClO4-, NO3-, AcO-, CF3COO-, C6H13COO- in PhSO-) polialilamina z različnimi stopnjami nevtralizacije (od 0 % do 120 %) sem pri 20 °C oziroma 25 °C izmeril viskoznost, viskozni in elastični modul ter določil zeta potencial in hidrodinamski radij. Preučeval sem odvisnost teh lastnosti od vrste protiionov, koncentracije polielektrolita, molekulske mase polielektrolita in stopnje nevtralizacije. V delu skušam pojasniti vpliv ionov na izmerjene lastnosti raztopin. With ion exchange chromatography I substituted the chloride ions in a solution of poly(allylamine hydrochloride) with hydroxide ions, obtaining a mildly basic solution of polyallylamine. I prepared measuring solutions of polyallylamine salts by adding different acid solutions to the batch solution of polyallylamine. The aqueous solutions of chosen polyallylamine salts (F-, Cl-, Br-, I-, ClO4-, NO3-, AcO-, CF3COO-, C6H13COO- in PhSO3-) with different degree of neutralization (from 0 % to 120 %) were characterized by measuring viscosity, elastic and viscous modulus as well as zeta potential together with hydrodinamic radious. I studied the effect of counterion type, polyelectrolyte concentration, polyelectrolyte molecular mass and the degree of neutralization on solution properties. In my thesis I explain the impact different ions have on the solution.

Cilj diplomskega dela je pripraviti poskus s področja seznanjanja s sistemi dinamike prvega in drugega reda, ki bi ga pri laboratorijskih vajah študenti lahko izvedli samostojno. Poskus bi moral biti ponovljiv ter izbran tako, da bi si študenti lahko čim lažje predstavljali vplive parametrov na odziv eksperimentalnega sistema. Zaželeno je, da bi bilo ujemanje med teoretično napovedjo, ki sledi iz nastavitev parametrov pri poskusu, čim boljše. Izidi poskusa bi se tako morali čimbolj ujemati z napovedmi teorije dinamike sistemov prvega in drugega reda. Za dosego tega cilja je bilo potrebno najti primerne pogoje in določiti najbolj ustrezne parametre, ki dobro ponazarjajo razliko med dinamiko sistemov prvega in drugega reda. Kot nazoren eksperimentalen sistem, ki ustreza tem zahtevam, smo identificirali sistem dveh zaporedno povezanih čaš (posod), v katerih je zagotovljeno dobro mešanje tekočine v čašah, skozi čaši pa se pretaka raztopina elektrolita. Spreminjanje koncentracije elektrolita pri spremembi sestave tekočine, ki vteka v sistem, smo spremljali konduktometrično. Ujemanje med eksperimentalnimi rezultati ter teoretičnimi napovedmi smo pri poskusih prikazali grafično. The objective of this diploma work is setting up an experiment that would demonstrate the dynamic response of the first and of the second order in continuous-flow systems. Additionally, such an experiment should be simple enough to be independently carried out by students. The experiment should give predictable responses which can be predicted in advance by strong relation between the values of physically meaningful parameters and the influence of this parameters on the outcome of the experiment. It is preferred that the experimental results quantitatively match to the theoretical predictions calculated upon the values of the crucial parameters measured at the beginning of the experiment. As a suitable experimental system meeting the given criteria we have identified a system consisted of two consecutively connected beakers whose content is efficiently stirred during the constant flow of the electrolyte solution through the system and exposed to a step change of the concentration of electrolyte solution flowing through the system. Time depended electrolyte concentration in each of two beakers is monitored by measuring conductivity of electrolyte solution. The agreement of experimental results and theoretical prediction is shown on graphs.

V diplomski nalogi je predstavljen didaktični modul PCT56 za umerjanje merilnikov tlaka in njegovo delovanje. Opisan je način, kako si je podjetje Armfield, ki proizvaja ta didaktični modul, zamislilo pedagoško rabo tega učnega pripomočka. Opisal sem princip delovanja merilnikov, ki so vključeni v modul PCT56 in predstavil svoje videnje, kako bi lahko nadgradili rabo opisanega modula ter ga vključili v nabor obstoječih laboratorijskih vaj pri predmetu Meritve in osnove regulacije procesov na Fakulteti za kemijo in kemijsko tehnologijo v Ljubljani. Zaradi omejitve študentskega dela v laboratorijih kot posledice epidemije koronavirusne bolezni svoje zamisli nisem mogel praktično preizkusiti v laboratoriju. The didactic module PCT56 for calibration of pressure gauges and its functioning are presented in diploma thesis. It is described how the company Armfield, which manufactures this didactic module, conceived the pedagogical use of this teaching aid. I described the operating principle of pressure sensors, which are included in the PCT56 module and presented my idea how to upgrade the use of this module and incorporate it into the set of existing laboratory exercises within the course “Measurements and fundamentals of process control“ at the Faculty of Chemistry in Chemical Technology in Ljubljana. Due to the ban of student work in laboratories as a consequence the coronavirus disease pandemic, I was unable to practically test my idea in the laboratory.

Kapilarna elektroforeza (angl. capillary electrophoresis) je analizna separacijska tehnika, katere prednost pred drugimi separacijskimi tehnikami je, da za analizo zahteva manjšo količino vzorcev in topil kot nekatere druge separacijske tehnike. Separacija poteka v električnem polju znotraj kapilare, napolnjene s pufrsko raztopino. Osnovni princip ločbe temelji na klasični elektroforezi in elektroosmotskem toku. S pojmom elektroforeza označujemo migracijo ionov pod vplivom električnega polja, medtem ko z izrazom elektroosmotski tok poimenujemo gibanje celotne raztopine elektrolita v kapilari proti katodi zaradi delno deprotoniranih silanolnih skupin na steni kapilare in prebitka kationov v pufru. Z elektroforezo ločimo delce z različnimi naboji, saj slednji znatno vplivajo na elektroforetske mobilnosti delcev, kot tudi delce z enakimi naboji, če so različnih velikosti ali oblik. V svojem delu sem želela z metodo kapilarne elektroforeze določiti elektroforetsko mobilnost fulerenheksamalonatnega iona, ki nastane pri ionizaciji fulerenheksamalonske kisline Th-C66(COOH)12. Elektroforetsko mobilnost sem izračunala iz izmerjenih migracijskih časov vzorca in acetona, električne napetosti na kapilari in dolžine kapilare. Ker je fulerenheksamalonska kislina občutljiva na delno dekarboksilacijo, smo na posnetih elektroferogramih opazili dva vrhova: prvi izvira iz nedegradirane kisline Th-C66(COOH)12, drugi pa je najverjetneje posledica prisotnosti enkrat dekarboksilirane fulerenheksamalonske kisline, C66H(COOH)11. Spreminjala sem pogoje ločbe, raztopino vzorca nakisala in jo segrevala pri višji temperaturi ter s tem pospešila delno dekarboksilacijo. Namerna degradacija vzorca se je odrazila tudi na elektroferogramih: pojavilo se je več novih vrhov, ki so bili posledica degradacije spojine, ko je iz molekule izstopila več kot le ena molekula CO2. V svoji diplomski nalogi sem med drugim tudi želela ugotoviti, kolikšna je ponovljivost izvedenih meritev elektroforetskih mobilnosti, kako na elektroforetsko mobilnost vplivata koncentracija pufra in napetost na kapilari, kakšna je učinkovitost ločbe, resolucija ter hidrodinamski polmer fulerenheksamalonatnega iona. Capillary electrophoresis is an analytic separation technique, of which advantage over other separation techniques is that it requires smaller quantities of samples and solvents, when compared with some other separation techniques. Separation occurs under the influence of an electric field inside the capillary, filled with a buffer solution. The basic separation principle is based on classical electrophoresis and the electroosmotic flow. With the phrase electrophoresis we define the migration of ions under the influence of the electric field, meanwhile the term electroosmotic flow defines the movement of an entire electrolyte solution towards the cathode due to partially deprotonated silanol groups on the capillary wall and the consequent excess of cations in the buffer solution. Using electrophoresis, we can separate particles carrying different charges, as they significantly affect electrophoretic mobilities of them, and we can also separate particles of the same charge if they differ in size or shape. In this work, I wanted to determine the electrophoretic mobility of the fullerenehexamalonate ion with the use of capillary electrophoresis, which can be accomplished through complete ionization of fullerenehexamalonic acid Th-C66(COOH)12. I have calculated its electrophoretic mobility from the measured migration times for the analysed ion and acetone, applied voltage on the capillary, and the length of the capillary. Because fullerenehexamalonic acid is sensitive to partial decarboxylation, two peaks were observed in recorded electropherograms: the first peak belonged to non-degraded acid Th-C66(COOH)12, and the second one probably occurred due to the presence of once decarboxylated fullerenehexamalonic acid, C66H(COOH)11. I varied the conditions of separation, I acidified the sample and heated it to higher temperatures, in order to provoke its accelerated partial decarboxylation. This purposeful decarboxylation also reflected in the electropherograms: several new peaks were observed due to degradation of the compound when more than one CO2 molecule was released from the original molecule. I also wanted to determine the repeatability of our measurements of electrophoretic mobilities, how electrophoretic mobility is affected by the buffer concentration and voltage on the capillary, the separation efficiency, resolution and the hydrodynamic radius of the fullerenehexamalonate ion.

Vodikova vez je privlačna interakcija med vodikovim atomom molekule ali molekulskega fragmenta X-H, kjer je X bolj elektronegativen kot vodik, in atomom ali skupino atomov iste ali različne molekule, kjer obstaja dokaz za tvorbo take vezi.Jakost vodikovih vezi je odvisna od lokalnega okolja. Vodikove vezi narekujejo lastnosti marsikateri snovi.Najbolj znan sistem z vodikovimi vezmi je voda. Anomalije se v vodi pojavijo ravno zaradi vodikovih vezi. Voda je odlično topilo za ionske in polarne spojine. Prisotnost ionov v vodni raztopini vpliva tudi na jakost vodikove vezi med molekulami vode. Vodikova vez je pomembna interakcija tudi v bioloških sistemih. Poleg hidrofobnih interakcij ima ključno vlogo pri zvijanju proteinov in ohranjanju nativne strukture. Z vodikovimi vezmi so med sabo povezane dušikove baze v molekuli DNA, zaradi česarse molekula zvije v obliko dvojne vijačnice.V zadnjem času so predmet mnogih raziskav hidrogeli, kjer je vodikova vez ena izmed pomembnejših interakcij. Razvili so tudi nekaj močnih hidrogelov, kjerso ključne interakcije prav vodikove vezi. The hydrogen bond is an attractive interaction between a hydrogen atom from a molecule or a molecular fragment X-H in which X is more electronegative than H, and an atom or a group of atoms in the same or a different molecule, in which there is evidence ofbond formation. Strengthof hydrogen bonds depends on local environment.Hydrogen bonds have a significant impactonthe properties of many substances. The most famoussystem with hydrogen bonds is water. Anomalies occur in the water due to occurrenceof hydrogen bonds. Water is an excellent solvent for ionic and polar compounds. The presence of ions in the aqueous solution also affects the strength of the hydrogen bond between the water molecules.Hydrogen bonding is also an important interaction in biological systems. In addition to hydrophobic interactions, it plays a key role in protein folding and maintaining native structure. In DNA molecule, the nitrogenous bases are linked to each other with hydrogen bonds, which causes the moleculeto twist into double helix.Recently, the hydrogels have been the subject of many researches, where the hydrogen bond is one of the most important interactions. Some strong hydrogels were developed, where the key interactions are hydrogen bonds.

V diplomski nalogi smo merili gostote vodnih raztopin različnih alkalijskih halidov in njihovih binarnih mešanic z namenom, da preučimo volumske spremembe pri mešanju teh raztopin. Merili smo mešanice dveh raztopin različnih soli enakih koncentracij, pri tem pa smo spreminjali tako koncentracijo teh elektrolitov kakor tudi medsebojna volumska razmerja, v katerih smo mešali ti raztopini. S temi meritvami smo želeli preveriti, ali je z natančnim merjenjem gostot možno potrditi teorijo o ujemanju afinitet ionov do vode. Predpriprava merjenih raztopin je zajemala natančno pripravljanje raztopin s tehtanjem in preverjanje koncentracij s potenciometrično titracijo. Gostote vseh raztopin in njihovih mešanic smo merili pri 25 °C s pomočjo gostotomera na nihajočo U-cevko. Dobljene meritve so nihajni časi, iz katerih smo na podlagi predhodno umerjenega gostotomera izračunali gostote. Iz gostot smo izračunali realne volumne raztopin in jih primerjali z volumni, ki bi jih imele te raztopine, če bi se vedle idealno. Odstopanja od idealnega obnašanja raztopin smo predstavili v grafih kot funkcijo volumskega razmerja mešanja in koncentracije. Pri mešanju raztopin dveh elektrolitov, ki sta vsebovala skupni ion, so bile volumske spremembe tako majhne, da so bile te spremembe velikostnega reda eksperimentalnih napak. Največje volumske spremembe smo opazili pri mešanju raztopin NaBr in KF višjih koncentracij (največjo volumsko spremembo ravno pri najvišji, to je 4 M raztopini). Zaradi precej podobnih ionskih radijev natrijevega in kalijevega iona je pri tem mešanju opažene volumske spremembe težko pripisati veljavnosti teorije o ujemanju afinitet ionov do vode. So pa te volumske razlike lahko tudi posledica eksperimentalnih napak zaradi interakcije fluoridnih ionov s stekleno oscilirajočo cevko. In this diploma thesis we measured the density of solutions of different alkali halides and their binary mixturesto examine the volume changes that occur when the solutions are mixed. The mixing of chosen two solutions of diferent salts was carried out with solutions of the same concentration as a function both of the concentration and of the volume ratios between the both solutions. Using accurately measured densities of these volume changes we wanted to verify if the law of matching water affinities can be confirmed with accurate density measurements. Preparation of the measured solutions consisted of weighing and precise determination of solution concentrations with the use of potentiometric titration. The densities of the solutions were determined with the help of an oscillating U-tube density meter at 25 °C. From the measured oscillating times we calculated the densities of solutions the density meter was calibrated beforehand. Using these densities we calculated the real volumes of the solutions and compared them to the volumes if the solutions were ideal. Deviations from the ideal behavior of the solutions are presented in graphs as a function of the volume ratio of mixing and concentration. When mixing solutions of two electrolytes containing a common ion, the volume changes were so small that these changes were of the order of magnitude of the experimental errors. The largest volumetric changes were observed in mixing of NaBr and KF solutions of higher concentrations (the largest volumetric change was exactly at the highest, i.e., 4 M solution). Due to the rather similar ionic radii of sodium and potassium ions it is difficult to attribute the validity of the law of matching water affinities from the observed volume change during mixing. Morever, these observed differences may also be due to experimental errors as a result of the interaction of fluoride ions with a glass oscillating tube.

Svetloba je elektromagnetno valovanje, ki ga določajo svetlobni tok, njegova gostota in frekvenčni spekter. Skozi prostor potuje v obliki valov, ki imajo svojo valovno dolžino. Najpogosteje merimo ultravijolično, vidno in infrardečo svetlobo. Osvetljenost lahko definiramo kot skupni vpadajoči svetlobni tok na enoto površine. Poznamo in merimo vertikalno, horizontalno in cilindrično osvetljenost. S pomočjo merilnikov osvetljenosti ugotavljamo primernost razsvetljave za opravljanje posameznih opravil. Glede na njihovo kakovost jih ločimo v več kakovostnih razredov. Light is an electromagnetic radiation determined by the light flux, its density and the frequency spectrum. It travels through the environment in the form of waves that have their own wavelength. Most common are ultraviolent, visible and infrared light. Illumination can be defined as the total incident luminous flux per unit area. We know and measure vertical, horizontal and cylindrical illumination. With the help of light meters, we determine the suitability of lights for individual tasks. Depending on their quality, we separate them into several quality classes.

Zakon o ujemanju afinitet ionov do vode, ki ga je intuitivno postavil K. D. Collins, predpostavlja, da nasprotno nabiti ioni z enakimi ali z zelo podobnimi afinitetami do vode med seboj tvorijo kontaktne ionske pare (CIP), ioni z dovolj različnimi afinitetami do vode pa ionskih parov ne tvorijo. V magistrskem delu sem sledeč Collinsovem zakonu proučevala mešanje različnih raztopin alkalijskih halidov. Osredotočila sem se predvsem na analizo toplotnih efektov nastalih pri izotermnem mešanju vodnih raztopin različnih parov alkalijskih halidov enakih koncentracij, izvedenem na izotermnem titracijskem kalorimetru (ITC). Z namenom, da bi potrdila rezultate meritev z ITC kalorimetrom, sem izmerila še električne prevodnosti ob mešanju vodnih raztopin različnih parov soli in za dva para soli tudi gostote takšnih mešanic raztopin soli. Primarni cilj raziskovanja je bil, da ugotovim, ali pri določenih parih soli (glede na Collinsovo pravilo) prihaja do tvorbe kontaktnih ionskih parov (CIP). Rezultati entalpij mešanja so pokazali, da pri po velikosti enakih (zelo podobnih) ionih ne prihaja do obsežne tvorbe CIP (kar smo potrdili tudi z meritvami električne prevodnosti). Iz izmerjenih toplot mešanja (linearno naraščanje toplot s spreminjanjem sestave mešanice soli in majhni toplotni efekti) sem ugotovila, da pri mešanju večine parov soli med seboj ne prihaja do kakršnih koli drugih nepričakovanih procesov. Izjeme so bile pri dodajanju raztopine CsF (in tudi LiF) v raztopino druge soli, kjer na grafu odvisnosti integralne toplote mešanja ΔHint. od deleža dane soli v mešanici raztopin dveh soli (X(MX)) vidimo, da se vrednost ΔHint. na dveh ali treh delih vsake krivulje ustali. Razlog za dano sosledje endotermnih toplotnih efektov je vsaj delno posledica hidrolize fluoridnega iona in interakcije fluoridih ionov s steno titracijske celice. Meritve entalpij mešanja so tudi pokazale, da so entalpije mešanja danega para soli tem večje, čim višja je začetna koncentracija obeh raztopin soli. Law of matching water affinities is intuitive law postulated by K. D. Collins. This law assumes that pairs of ions of the opposite charge with identical or very similar water affinity form contact ion pairs (CIPs) while no ion pairs are formed between ions with different water affinity. In the present master thesis, due to the Collins law, mixing of aqueous alkali halides solutions has been examined. The main focus was on analyses of heat effects, which arise by the isothermal mixing of different pairs of aqueous alkali halides solutions of the same concentration, determined by isothermal titration calorimetry (ITC). In order to validate the results measured on ITC, we also measured the electrical conductivity and density of such aqueous alkali halide mixtures. Primary objective of the research was to discover, if formation of contact ion pairs occur when certain pairs of salts (according to Collins’ law) are mixed. The measured values of the enthalpy of mixing ions of the same (very similar) sizes do not indicate extensive formation of CIPs. This was confirmed by electrical conductivity measurements. From the measured heats of mixing, I have found due to low thermal effects and linear increase (decrease) of heat by changing the composition of the salt mixture that when mixing most of the salt pairs there are no other unexpected processes. Exceptions were made when adding a solution of CsF (and also LiF) to the solutions of second salt, where is in the graph ΔHint. (X(MX)) the value of ΔHint. on two or three parts of each curve settle down. The reason for the given function of thermal effects is at least in part due to the hydrolysis of the fluoride ion and possibly also due to the interaction of fluoride ions with the wall of titration cell. Measurements of the enthalpy of mixing has also showed that the enthalpy of mixing for a given salt pair is increasing with initial concentration of involved aqueous salt solutions.

Zakaj nekateri ioni Hofmeistrove vrste bolje stabilizirajo strukture proteinov kot drugi? Zakaj so nekateri bolj učinkoviti pri izsoljevanju, drugi pa pri vsoljevanju? Kako sploh deluje interakcija ionov s proteini in kakšna je vloga vode pri celotnem mehanizmu delovanja ionov v elektrolitskih raztopinah? To so samo nekatera od vprašanj, ki raziskovalke in raziskovalce z različnih področij kemije združujejo že skoraj 130 let. Z razvojem novih tehnologij inštrumentov, analize in računalniškega modeliranja, je bilo v zadnjih desetletjih doseženih kar nekaj bistvenih napredkov pri razumevanju Hofmeistrovega efekta, smo pa vseeno še nekje pri začetku. Ravno ti napredki so ustvarili rodovitna tla za številna nova polja raziskav tako na področju fizikalne kemije, kot tudi na področju biokemije. V svoji diplomski nalogi poskušam obrazložiti nekaj osnovnih dejstev o proteinih v elektrolitskih raztopinah, vlogi vode pri mehanizmih delovanja ionov Hofmeistrove vrste in predstaviti nekaj bistvenih raziskav na to temo. Why are some ions from the Hofmeister series better at stabilizing the structure of proteins than others? Why are some ions better at salting-out, while others are better at salting-in? How does the interaction mechanism between ions and proteins function and what role does water play during the ionic mechanism in electrolyte solutions? These are just some of the questions that have brought researchers from different fields of chemistry together for almost 130 years now. With the development of new technologies for instruments, analysis and computer simulations, the last couple of decades have been marked by significant advances in the understanding of the Hofmeister effect. And yet, we are still at the beginning. It is these advances that created a fertile ground for a vast number of new fields of research within the field of physical chemistry, as well as the field of biochemistry. In my bachelor thesis I try to explain some basic facts about proteins and electrolyte solutions, the role of water in the working mechanism of Hofmeister ions, and to illustrate some essential researches on this topic.

V okviru magistrskega dela smo po znanem postopku sintetizirali natrijevo sol fulerenheksamalonske kisline (FHMA), ki smo jo nato z ionsko izmenjavo pretvorili v njeno kislinsko obliko. Z nevtralizacijo kisline FHMA z raztopinami alkalijskih hidroksidov smo pripravili litijevo, natrijevo in cezijevo sol FHMA (LiFHM, NaFHM in CsFHM). Raztopino LiFHM s koncentracijo 0,005 mol COO-skupin / dm3smo pri treh različnih temperaturah (5,0 ºC 25,0 ºC 45,0 ºC) titrirali z 0,15 molarnimi raztopinami izbranih 1:1 alkalijskih (LiCl, NaCl, CsCl) in tetraalkilamonijevih (tetrametil-, tetraetil-, tetrapropil-, in tetrabutilamonijevih) kloridov, pri tem pa smo merili izmenjano toploto (z uporabo izotermnega titracijskega kalorimetra) in (samo pri 25,0 °C) električno prevodne (konduktometer) spremembe v titriranih raztopinah. As part of our master’s thesis a well-known procedure was used to synthesise sodium salt of fullerenehexamalonic acid (FHMA), which was then transformed into its acidicform by means of ion exchange. Lithium, sodium and caesium salts of FHMA were prepared by neutralising FHMA with solutionsof alkali hydroxides. Solution of LiFHM with concentration of 0.005mole COO-groups / dm3was titrated at three different temperatures (5.0 ºC 25.0 ºC 45.0 ºC) with selected alkali (LiCl, NaCl, CsCl) and tetraalkylammonium (tetramethyl-, tetraethyl-, tetrapropyl-, and tetrabutylammonium) chlorides, during which exchanged heat (by means of isothermal titration calorimeter) and (only at 25.0 ºC) electroconductivity (conductometer) changes were being measured.