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Determination of anionic surfactants with different number of C atoms using sensors based on quaternary ammonium salts
No full textTenzidi kao površinski aktivne tvari sadrže hidrofilnu glavu i hidrofoban rep te kao takvi smanjuju površinsku napetost. Ovisno o naboju glave, dijele se na anionske, kationske, amfoterne te neionske tenzide. Jedna od najčešće korištenih analitičkih metoda kojom se određuju tenzidi jest potenciometrijska titracija koja se temelji na mjerenju razlike potencijala između indikatorske i referentne elektrode. Cilj ovog rada bio je ispitati točnost određivanja anionskih tenzida s različitim brojem ugljikovih atoma u hidrofobnom dijelu molekule (C10, C12, C14), koristeći tenzidne senzore na bazi kvaternih amonijevih soli. Testirano je pet tenzidnih senzora: KA1-TPB, KA2-TPB, KA3-TPB, KA4-TPB te KA5-TPB pri čemu su svi pokazali zadovoljavajuću točnost što ukazuje na činjenicu da točnost određivanja anionskih tenzida ovim senzorima ne ovisi o vrsti anionskog tenzida.Surfactants in their structure contain hydrophilic head and hydrophobic tale and they reduce surface tension. Depending on the charge of the head, surfactants are classified as anionic, cationic, amphoteric and nonionic surfactants. One of the most commonly used analytical methods for surfactants determination is potentiometric titration based on measuring the potential difference between the indicator and reference electrode. The aim of this paper was to examine the accuracy of the determination of anionic surfactants with different number of carbon atoms in the hydrophobic part of the molecule (C10, C12, C14), using surfactant sensors based on quaternary ammonium salts. Five surfactant sensors were tested: KA1-TPB, KA2-TPB, KA3-TPB, KA4-TPB and KA5-TPB. All of them showed satisfactory accuracy, which indicates the fact that the accuracy of anionic surfactants determination using these sensors does not depend on the type of anionic surfactant
Application of inorganic oxides in photocatalysis
No full textU današnjici, anorganski oksidi su pronašli različite primjene u industriji i zaštiti okoliša. Jedna od najzanimljivijih klasa anorganskih oksida su prijelazni metalni oksidi, zbog zanimljivih električnih i optičkih svojstava, kao i pogodnog energijskog procjepa. Kao takvi, našli su i primjenu u fotokatalizi i razgradnji organskih zagađivača u otpadnim vodama. U ovom diplomskom radu je sintetizirano sedam serija nanočestica bakrovog(II) oksida i niklova(II) oksida ultrazvučnom sintezom u ultrazvučnoj kupelji iz bakrovog(II) acetata monohidrata i niklova(II) acetata tetrahidrata - CuH, CuH1, CuH3, CuH5, CuE, NiH i NiE. Od karakterizacijskih metoda su korišteni PXRD, FT-IR, TGA, UV/VIS, UV/VIS NIR, TEM, SEM i XPS. Sličnost u veličini kristalita unutar serija uzoraka određena Sherrer-ovom i Williamson - Hall metodom je pokazala da vrijeme ultrazvučne sinteze nema utjecaj na veličinu kristalita, a time ni na veličinu energijskog procjepa kao ni na fotokatalitičku aktivnost sintetiziranih uzoraka. Najmanji optički energijski procjep ima CuH uzorak te on iznosi 1,5 eV, dok najveći energijski procjep ima CuE uzorak i on iznosi 4,025 eV. Testirana je fotokatalitička aktivnost uzoraka na razgradnju metilen plavog. Utvrđeno je da s povećanjem energijskog procjepa dolazi do smanjenja konstante brzine fotokatalitičke reakcije. Iz ovisnosti promjene apsorbancije o vremenu izračunata je učinkovitost fotokatalizatora prema kojoj najveću učinkovitost i fotokatalitičku aktivnost ima uzorak CuH s konstantom brzine reakcije od 8,1 · 10-3 min-1. S druge strane, najmanju učinkovitost i fotokatalitičku aktivnost ima uzorak CuE s konstantom brzine reakcije od 3,73 · 10-3 min-1.Nowadays, inorganic oxides have found various applications in industry and environmental protection. One of the most interesting classes of inorganic oxides is transition metal oxides. High interest is due to their interesting electrical and optical properties, as well as a suitable bandgap. As such, they have been found and applied in photocatalysis and decomposition of organic pollutants in wastewater. In this master's thesis, seven series of nanoparticles of copper(II) oxide and nickel(II) oxide were synthesized by the ultrasonic synthesis in an ultrasonic bath from copper(II) acetate monohydrate and nickel(II) acetate tetrahydrate - CuH, CuH1, CuH3, CuH5, CuE, NiH i NiE. Of the characterization methods, PXRD, FT-IR, TGA, UV/VIS, UV/VIS NIR, TEM, SEM, and XPS are used. The similarity in crystal size within the series of samples, determined by the Sherrer and Williamson - Hall method, showed that the time of ultrasonic synthesis does not affect the size of the crystallite, bandgap, and photocatalytic activity as well. The smallest optical bandgap value of 1.5 eV has the CuH sample, while the largest bandgap value of 4.025 eV has the CuE sample. The photocatalytic activity of the samples was tested on the degradation of methylene blue. It was found that with an increase in the bandgap there is a decrease in the rate constant of the photocatalytic reaction. Depending on the changes in absorbances over time, the efficiency of the photocatalyst was calculated according to which the CuH sample with the reaction rate constant of 8.1 · 10-3 min-1 has the highest efficiency and photocatalytic activity. On the other hand, the CuE sample with a reaction rate constant of 3.73 · 10-3 min-1 has the lowest efficiency and photocatalytic activity
Preparation and Application of thin hydrogel film in optical sensors
No full textOtapanjem kitozana u otopini octene kiseline te umrežavanjem pomoću 2,2'-bipiridin-4,4'-dikarboksilne kiseline dobiva se hidrogel koji na svakom mjestu umreženja posjeduje bidentantni N-donorni ligand koji ima sposobnost kompleksiranja Fe iona. Dodatkom Fe(II) soli u vodenoj otopini dolazi do kompleksiranja željeza unutar hidrogela. Dodatkom pomoćnog liganda, kao što je TPTZ (2,4,6-tri(2-pyridyl)-1,3,5-triazine), hidrogelu koji unutar svoje mreže posjeduje kompleksirano željezo dolazi do nastajanja plavo obojenog hidrogel-(2,2'-bipiridin-Fe(II)-TPTZ) kompleksa. Djelovanjem oksidansa, kao što je H2O2, na takav hidrogel dolazi do njegovog obezbojenja, a redukcijskim djelovanjem antioksidanasa ponovno nastaje plavo obojenje. Ova reakcija oksidacije-redukcije unutar dobivenog hidrogela je reverzibilna.By dissolving chitosan within acetic acid solution followed by crosslinking via 2,2'-bipyridine-4,4'-dicarboxylic acid a hydrogel containing a bidentate nitrogen ligand at each crosslink site is formed which has the ability to bind Fe ions. Addition of Fe(II) salts in aqueous solution creates an iron complex within the hydrogel. An additional ligand such as TPTZ (2,4,6-tri(2-pyridyl)-1,3,5-triazine) has the ability to bind to iron which is already bound within the hydrogel forming a blue colored hydrogel-(2,2'-bipyridine-Fe(II)-TPTZ) complex. Oxidation said complex via oxidizing agent such as hydrogen peroxide induces loss of color after which it is possible to again reduce the colorless Fe(III)-TPTZ complex via an antioxidative agent that results in return of the blue color. The Aforementioned oxidation-reduction reaction has been proven to be reversible
Determination of intermolecular interactions by Hirschfeld surface analysis
No full textRazvojem kristalnog inženjerstva i sve većom potrebom za dizajniranjem materijala specifične uporabe, znanstvenici su shvatili potrebu boljeg razumijevanja međumolekulskih interakcije u kristalima. Međumolekulske interakcije određuju brojna fizikalna i kemijska svojstva. Kristalno inženjerstvo posebnu prednost daje makrocikličkim supramolekulskim spojevima zbog lake pripreme i široke potencijalne uporabe. Iako je rendgenska strukturna analiza i dalje osnovni način određivanja strukture kristala, ona sama ne daje dovoljan uvid u međumolekulske interakcije koje povezuju molekule. Uvođenjem novog načina opisivanja elektronske gustoće molekule pomoću Hirshfeldove površine, omogućen je vizualni prikaz i mapiranje područja koja sudjeluju u međumolekulskim interakcijama. Detaljnim proučavanjem podataka dobivenih iz Hirshfeldove površine moguće je pretpostaviti dominantne međumolekulske interakcije, područje molekule koje sudjeluje u interakciji, energiju vezanja te način pakiranja molekula u kristale. U radu je provedena analiza Hirshfeldovih površina 9 makrocikličkih spojeva od kojih je 8 analiza bilo uspješno. Dobiveni rezultati potom su uspoređeni s rendgenskom strukturnom analizom odabranih spojeva te su za neke od molekula predloženi dodatni načini povezivanja u kristalnoj strukturi.With the development of crystal engineering and the growing need to design materials of specific use, scientists have realized the necessity for a better understanding of intermolecular interactions in crystals. Intermolecular interactions determine a vast number of physical and chemical properties. Crystal engineering gives special preference to macrocyclic supramolecular compounds due to their easy preparation and wide potential use. Although X-ray structural analysis is still the basic way to determine crystal structure, it alone does not provide sufficient insight into the intermolecular interactions that link molecules into crystals. By introducing a new way of describing the electron density of a molecule using the Hirschfeld surface, it is possible to visually display and map the areas involved in intermolecular interactions. With a detail study of the data obtained from the Hirschfeld surface, it is possible to predict the dominant intermolecular interactions, the region of the molecule participating in the interaction, the binding energy, and the way the molecules are packaged into crystals. In this paper, Hirschfeld surface analysis was performed for 9 macrocyclic compounds, of which 8 analyses were successful. The obtained results were then compared with X-ray structural analysis of selected compounds, and some additional intermolecular binding methods in the crystal structure were proposed for some of the molecules
Degradation of pharmaceutical residues by gamma radiation
No full textCilj ovog rada bio je ispitati utjecaj gama-zračenja na degradaciju vodene otopine doksazosina, lijeka koji je poznati antihipertenziv i jedan od često korištenih farmaceutika. Istraživanje se provodilo u Laboratoriju za radijacijsku kemiju i dozimetriju, Zavoda za kemiju materija, Instituta Ruđer Bošković. Učinkovitost degradacije proučavana je pri različitim dozama zračenja, brzinama doza, pH vrijednostima otopine, u prisustvu hvatača radikala i u prisustvu anorganskih soli. Ozračeni uzorci analizirani su spektrofotometrijski i tekućinskom kromatografijom visoke djelotvornosti s DAD detektorom. Pokazano je da su •OH glavne reaktivne vrste odgovorne za razgradnju doksazosina, a efikasnost razgradnje polaznog spoja raste s porastom doze gama-zračenja. Prisutnost nitrata je imala značajniji utjecaj na razgradnju doksazosina u usporedbi s karbonatima i fosfatima. Optimalna pH vrijednost za razgradnju vodene otopine doksazosina je u neutralnom, blago kiselom području (pH = 6,5), dok je pri izrazito kiselim i baznim uvjetima razgradnja bila slabija. Utvrđeno je da je razgradnja doksazosina u bunarskoj vodi sporija u usporedbi s ultračistom vodom što ukazuje da organske i anorganske komponente otopljene u vodama utječu na efikasnost radiolitičke degradacije doksazosina.The aim of this study was to investigate the effect of gamma-radiation on the degradation of doxazosin (a widely used antihypertensive drug) in aqueous solution. The research was conducted at the Radiation Chemistry and Dosimetry Laboratory, Division of Materials Chemistry, Ruđer Bošković Institute. The efficiency of degradation was studied under different absorbed doses, dose rates, pH values and in the presence of radical scavengers and inorganic ions. The irradiated samples were analyzed by UV/VIS spectrophotometry and high performance liquid chromatography with diode array detector. It was found that •OH are the main reactive species responsible for the degradation of doxazosin, the efficiency of degradation being higher with increasing dose of gamma radiation. The presence of nitrates had a stronger effect on doxazosin degradation compared to carbonates and phosphates. An optimal pH for doxazosin degradation was in the neutral, slightly acidic range (pH = 6.5), while degradation was slower under extremely acidic or alkaline conditions. It was found that the degradation of doxazosin in well water was much slower compared to ultrapure water, suggesting that organic and inorganic components dissolved in natural waters influence the efficiency of radiolitic degradation of doxazosin
Determination of vitamin E content in laying hens feed
No full textVitamin E je organska tvar topiva u mastima. Vrlo je važan za zdravlje ljudi, a budući da ga ljudsko tijelo ne može samostalno proizvoditi, potrebno ga je unositi hranom ili dodacima prehrani. Također je važan dodatak prehrani u hrani za kokoši nesilice zbog održavanja fizioloških funkcija i proizvodnje jaja te se na taj način povećava unos vitamina E i u ljudsko tijelo. Cilj istraživanja bio je utvrditi sadržaj vitamina E u hrani za kokoši nesilice i hrani za kokoši obogaćenu vitaminom E i raznim uljima. Korištene su tri različite metode: izravna ekstrakcija metanolom, izravna ekstrakcija ultrazvukom i ekstrakcija s prethodnom saponifikacijom. Nakon ekstrakcije uzorci su analizirani pomoću tekućinske kromatografije visoke djelotvornosti. Koncentracija vitamina E određena je u uzorcima hrane za kokoši dostupne na tržištu, u uzorcima s dodanim uljima, s dodatkom drugih nutricina (selena i luteina) i u hrani s dodatkom vitamina E i drugih nutricina. Najveća koncentracija vitamina E pronađena je u uzorcima s dodatkom vitamina E i drugih nutricina (725,940 mg/kg hrane), a najniža koncentracija vitamina E u uzorcima s dodatkom drugih nuticina (selen) 193,242 mg /kg hrane.Vitamin E is an organic substance soluble in fats. It is very important for human health and since the human body cannot produce it on its own, it is necessary to intake it through food or dietary supplements. It is also an important food supplement in laying hens feed due to the maintenance of physiological functions and egg production and in this way the intake of vitamin E in the human body increases. The aim of the study was to determine the content of vitamin E in laying hens feed and hens feed enriched with vitamin E and various oils. Three different methods were used: direct extraction with methanol, direct ultrasound extraction and extraction with prior saponification. After extraction, samples were analyzed by means of high-performance liquid chromatography. Concentration of vitamin E was determined in samples of hens feed available on the market, samples with added oils, with the addition of other nutricines (selenium and lutein) and food with the addition of vitamin E and other nutricines. The highest concentration of vitamin E was found in samples with the addition of vitamin E and other nutricines (725.940 mg/kg of hens feed) and the lowest concentration of vitamin E was found in samples with the addition of other nutricines (selenium) 193.242 mg/kg of hens feed
Review and comparison of methods for calculating the Hildebrand and Hansen solubility parameters
No full textParametar topljivosti svojstvo je koje se veže uz otapala i koristi za predviđanje svojstava otapala ili smjesa otapala te omogućuje da se izabere što pogodnije otapalo koje će se koristiti u npr. industriji premaza. U ovome radu opisana su dva parametra topljivosti. Hildebrandov parametar topljivosti koji se više primjenjuje kod spojeva koji ne sadrže specifične interakcije poput vodikovih veza. Drugi tip je Hansenov parametar koji je Hildebrandov parametar topljivosti podijelio na tri dijela uzimajući u obzir tri tipa interakcija. Hansenov se parametar sastoji od disperzijskog parametra, polarnog parametra i parametra topljivosti vodikovih veza. Zajedničko svojstvo kod oba tipa parametra je da podržavaju inačicu "slično se u sličnom otapa" te određuju koje otapalo se slaže sa određenim polimerom, a koje ne. Izračuni se vrše preko niza jednadžbi te mora postojati uvjet da je slobodna Gibbsova energija negativna. Moderna tehnologija nam omogućuje da se pomoću računalnih programa brže dođe do rezultata, te se na taj način izbjegnu tradicionalne eksperimentalne metode određivanja parametra topljivosti. Često se uz računanje parametra topljivosti veže i metoda grupnih doprinosa koja služi za određivanje svojstava otapala što pomaže pri izboru otapala za miješanje sa odgovarajućim polimerom.The solubility parameter is a solvent-binding property. It is used to predict the properties of solvents or solvent mixtures and makes it possible to select the most suitable solvent to be used in, for example, the coating industry. Two solubility parameters are described in this paper. First, the Hildebrand solubility parameter is more applicable to compounds with no specific interactions, such as hydrogen bonds. The second type is the Hansen parameter which divided the Hildebrand solubility parameter into three parts considering three types of interactions. The Hansen parameter consists of the dispersion parameter, the polar parameter, and the hydrogen-bonding parameter. A common feature of both parameters is that they support the "like dissolves like" principles and determine which solvent agrees with a particular polymer and which does not. The calculations are performed over a series of equations assuming that the free Gibbs energy is negative. Modern technology allows us to get results faster with the help of computer programs, thus avoiding traditional experimental methods for determining the solubility parameter. The group contribution method is often used to calculate the solubility parameter and some of the solvent properties and helps the choice of solvent for mixing with the appropriate polymer
Interdisciplinary investigation of the human dipeptidyl peptidase III mutants E480Q and T481M
No full textLjudska dipeptidil-peptidaza III (hDPP III) je metalopeptidaza koja cijepa dipeptide sa N-kraja oligopeptida, te posjeduje ETGE vezni motiv kao i transkripcijski faktor Nrf2. Nrf2 je odgovoran za aktivaciju ekspresije gena vezanih za antioksidativnu obranu stanice. Kada nema oksidativnog stresa, Nrf2 je vezan na protein Keap1 čime se omogućuje njegova ubikvitinacija. Pojavom oksidativnog stresa, Nrf2 se oslobađa iz kompleksa i translocira u jezgru gdje aktivira ekspresiju gena. Kompetativnim vezanjem proteina hDPP III na Keap1 onemogućava se ubikvitinacija Nrf2 čime se povećava njegova akumulacija u stanici. U ovom radu, u bakterijama su proizvedeni i pročišćeni mutanti proteina hDPPP III s mutacijama dviju aminokiselina (T481M i E480Q) čije su genomske sekvence pronađene na cBio portalu za genomiku raka. Biokemijskom karakterizacijom i usporedbom afiniteta vezanja divljeg tipa i mutiranih proteina ispitana je interakcija hDPP III s domenom Kelch proteina Keap1. Na temelju rezultata ovog ispitivanja mogu se donijeti pretpostavke o doprinosu mutacija na otpornost stanica raka na oksidativni stres.Human dipeptidyl-peptidase III (hDPP III) is a metallopeptidase that cleaves dipeptides from the N-terminus of the oligopeptide and has an ETGE binding motif as well as the transcription factor Nrf2. Nrf2 is responsible for activating the expression of genes associated with antioxidant cell defense. When there is no oxidative stress, Nrf2 is bound to Keap1 protein and thus allowing the ubiquitination of Nrf2. With the appearance of oxidative stress, Nrf2 is released from the complex and translocated into the nucleus where it triggers gene expression. Competitive binding of the hDPP III protein to Keap1 prevents the ubiquitination of Nrf2, which in turn increases the accumulation of Nrf2 in the cell. In this thesis, mutants of the hDPPP III protein with mutations of two amino acids (T481M and E480Q), whose genomic sequences were found on the cBio portal for cancer genomics, were produced in bacteria and purified. The interaction of hDPP III with the Keap1 protein was examined by biochemical characterization and by comparison of the binding affinity of wild-type and mutated proteins. Based on the results of this study, assumptions can be made about the contribution of the mutations to cancer cell resistance to oxidative stress
Potentiometric detection of thiabendazole
No full textTiabendazol (TBZ) je antifungalno sredstvo koje se najčešće koristi kao fungicid u voću i povrću. Budući da je potencijalno toksičan kada se unosi putem hrane, vrlo je bitno razviti nove metode za njegovo određivanje. Cilj ovog rada je bio razviti potenciometrijski senzor za određivanje TBZ-a koristeći ionski par TBZ-a i 5-sulfosalicilatnog aniona kao senzorski materijal. Metode koje su korištene za njegovo određivanje su bile direktna potenciometrija i Granova metoda. Senzorski materijal je inkorporiran u tekuću membranu ionsko selektivne elektrode (ISE). Prilikom optimizacije membrane, variran je postotak senzorskog materijala i vrsta plastifikatora. Najboljom se pokazala kombinacija 1 % senzorskog materijala i dibutil sebakata (DS-a) kao plastifikatora. Senzor je pokazao super Nernstovski nagib, široko mjerno područje i nisku granicu detekcije. Vrijeme odziva je bilo nekoliko sekundi, a mjerno pH područje od 2 do 4. Pokazao je dobru selektivnost prema TBZ-u. Svi parametri su doveli do brzog i točnog određivanja TBZ-a u realnim uzorcima.Thiabendazole (TBZ) is an antifungal agent that is mostly used as a fungicide in fruits and vegetables. Since it is potentially toxic and harmful when obtained through food, it is important to develop new methods for TBZ determination. The aim of this study was to develop potentiometric sensor for determination of TBZ using an ionic pair of TBZ and 5-sulfosalicylate anion as a sensor material. The methods that were used for sensor characterization and TBZ determination were direct potentiometry and the Gran method. The sensor material was incorporated in a liquid membrane of an ion-selective electrode. During the optimization of the membrane, the percentage of the sensor material and different plasticizers were varied. The chosen sensor with dibutyl sebacate as plasticizer and 1% of sensor material in the membrane showed the best results. The sensor showed a super-Nernstian slope, a wide measuring range, and a low limit of detection. The response time of the sensor was only a few seconds, and pH working range was between 2 and 4. It had a good selectivity towards TBZ. All these parameters led to fast and accurate determination of TBZ in real samples
Study of application of selected plants from Rosaceae family as alternative pH indicators
No full textPorodica Rosaceae, ružovke, je vrlo rasprostranjena porodica reda ružolike, Rosales. Predstavnici ove porodice lako se mogu pronaći, bilo kao divlje vrste u prirodi ili kao uzgojene ukrasne biljke, te imaju obojane listove, cvjetove i/ili plodove, za čiju su boju odgovorni različiti polifenolni spojevi. Ovi biljni pigmenti ovisno o pH vrijednosti otopine mijenjaju boju od crvene, ljubičaste, plave, zelene do žute, zbog čega bi pripadnici ove porodice mogli imati primjenu u pripremi alternativnih pH indikatora. Cilj rada bio je ispitati potencijal primjene odabranog biljnog materijala iz porodice Rosaceae kao alternativnih pH indikatora. U radu je korišten svježi, suhi i prerađeni biljni materijal (džem, sok, vino, čaj). Odabrane su prerađevine s najvišim sadržajem ciljanog biljnog materijala, bez dodatka drugog bilja, umjetnih bojila i drugih potencijalnih indikatora koji bi utjecali na dobivene rezultate. Rezultati istraživanja pokazuju na izuzetno veliki potencijal primjene biljnog materijala zbog svoje pristupačnosti, niske cijene, mogućnosti jednostavnog skladištenja te jednostavne pripreme. Od ispitanog biljnog materijala, među vizualno najdojmljivijima istakli su se trešnja, divlja kupina, ruže i određene sorte jabuke, dok se marelica, glog i mušmulica nisu istaknuli kao alternativni pH indikatori.The family Rosaceae, the rose family, is a very widespread family of the order Rosales. Representatives of this family can easily be found, either as wild species in the nature or as cultivated ornamental plants, and have colored leaves, flowers, and/or fruits, the color of which is a result of various polyphenolic compounds. Depending on the pH value of the solution, these plant pigments change color from red, purple, blue, green to yellow, which is why members of this family could be used in the preparation of alternative pH indicators. The aim of this study was to examine the potential application of selected plant material from the Rosaceae family as alternative pH indicators. Fresh, dry, and processed plant material (jam, juice, wine, tea) was used in this work. Products with the highest content of targeted plant material were selected, without the addition of other plants, artificial colors, and other potential indicators that would affect the obtained results. The results of this research show extremely high potential of used plant material due to its accessibility,low cost, easy storage and easy preparation. Of the examined plant material, cherries, wild blackberries, roses, and certain apple varieties stood out among the most visually impressive, while apricots, hawthorn, and hawthorn did not stand out as alternative pH indicators