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Synthesis of Schiff bases derived from 2-aminobenzoic acid
No full textSchiffove baze su spojevi koji se intenzivno istražuju od sedamdesetih godina prošlog stoljeća. Jedan od razloga je jednostavnost pripreme baza te njihova primjena u kemijskim i biološkim procesima. Načini sinteze, kao npr. klasična otopinska sinteza, koja podrazumijeva upotrebu organskih otapala i velik unos energije, polako se zamjenjuju novim alternativnim načinima, a jedan od njih je mehanosinteza. Jedan od najznačajnijih razloga zbog kojeg se istražuju nove metode sinteze je negativni utjecaj otapala na okoliš i količina otapala u reakcijama. Mehanokemija se pokazala kao dobra alternativa jer omogućava metode priprave Schiffovih baza bez upotrebe opasnih otapala te je energetski učinkovitija od klasičnih otopinskih sinteza. Ipak, mehanosinteze su slabo istražene i malo je podataka o utjecaju vlage ili para otapala na reaktivnost aromatskih amina i aldehida u čvrstom stanju. U ovome su radu mehanokemijskom sintezom pripravljene Schiffove baze izvedene iz aldehida i diamina ručnim usitnjavanjem u tarioniku te klasičnom otopinskom sintezom. Analiza spojeva dobivenih mehanosintezom vršila se FTIR spektroskopijom i termičkom analizom (TGA-DSC) pri čemu je ustanovljeno da smo mehanosintezom uspjeli dobiti željene produkte.Schiff base compounds have been intensely researched since 1970's. These compounds are popular research area because of the simplicity of their syntheses and a wide number of applications in chemical and biological processes. Different ways of syntheses, e.g. classic solution synthesis which use organic solutes and require high energy uptake, are slowly being replaced with new alternative procedures such as mechanosynthesis. The main drive for investigation and applications of these new methods is avoidance of negative effects that toxic solvents have on our environment, and also reduction of the amount of solvents used. Thus, mechanochemistry has shown to be a good method for Schiff base syntheses; it gives good yields without the need for hazardous solvents and is also more energy efficient than classic methods are. Nevertheless, mechanosyntheses are still not fully researched and there is a lack of data on the influence of humidity or vapour pressure on the reactivity of aromatic imines and aldehydes in solid state. In this paper Schiff bases derived from aldehydes and amines were synthesized by mechanochemical synthesis by hand grinding with pestle and mortar, and compared to the classic solution synthesis. The synthesized compounds were analysed with FTIR spectroscopy and thermal analysis (TGA- DSC). The results showed that wanted products were adequately synthesized in the process of mechanosynthesis
Lambert-Beer"s Law
No full textUV/VIS spektroskopija je eksperimentalna metoda određivanja koncentracije materijala u uzorku mjerenjem količine svjetla koju je uzorak apsorbirao. Metoda se temelji na Lambert- Beerovom zakonu koji daje funkcijski odnos između eksperimentalno određene fizikalne veličine, apsorbancije (A) i fizikalne veličine koja se određuje računski, koncentracije (c). Koncentraciju je moguće odrediti i grafički iz baždarnog dijagrama ovisnosti apsorbancije o koncentraciji. Posljedica međudjelovanja fotona i čestica koje apsorbiraju elektromagnetsko zračenje jest smanjenje intenziteta snopa s na . Zakon se može prikazati kao: gdje je A apsorbancija na danoj valnoj duljini svjetlosti, je molarni apsorpcijski (ekstinkcijski) koeficijent izražen u L , svojstven svakoj molekulskoj vrsti i ovisan o valnoj duljini svjetlosti, b je duljina puta svjetlosti kroz uzorak izražena u cm, a c je koncentracija tvari u otopini izražena u mol . Ovo je granični zakon pošto vrijedi samo za otopine s niskim koncentracijama i za izvore monokromatske svjetlosti. Lambert - Beerov zakon i UV/VIS spektroskopija su vrlo korisni jer omogućavaju kvantifikaciju i određivanje čistoće DNA iz bioloških uzoraka, praćenje kemijskih reakcija, identifikaciju tvari, određivanja različitih tvari i slično.UV/VIS spectroscopy is the experimental method used for determination of the concentration of a material in the sample by measuring the amount of light absorbed by a sample. The method is based on the Lambert-Beer's law that provides the function ratio between experimentally determined physical quantity, absorbance (A) and the physical quantity determined by calculation, concentration (c). Concentration can be determined graphically from the calibration curve of dependence of absorbance on concentration. The interaction between photons and particles that absorb electromagnetic radiation is the reduction of beam intensity from to . The law can be represented as: where A is the absorbance at a given wavelength of light, is the molar absorption (extinction) coefficient expressed in L , that is characteristic for each molecule and dependent on the wavelength of light, b is the length of the light path through the sample expressed in cm and c the concentration of the substance in the solution expressed in mol . This is the limiting law because it is only valid for low concentrations and for monochromatic light sources. Lambert-Beer's law and UV/Vis spectrophotometry are very useful because they provide quantification and determination of DNA purity of biological samples, chemical reaction monitoring, substance identification, determination of different substances and the like
Fluorescence detection of selenium in organic samples
No full textCilj ovog diplomskog rada je mjerenje koncentracije selenija u organskim uzorcima fluorescentnom spektrometrijom. Budući da selenij ne fluorescira, potrebno ga je označiti odgovarajućim markerom koji može fluorescirati. Kao takav marker koristi se 2,3- diaminonaftalen (DAN). Reakcijom DAN-a i selenija nastaje kompleks Se-DAN koji može fluorescirati te se na taj način mjeri selenij u uzorku. Za uzorke su uzeti suplementi u obliku tableta koji u sebi sadrže znatnu količinu selenija. Osim što je bilo potrebno pronaći najbolji način digestije takve tablete, težilo se tome da se odabere otapalo u kojemu će se kompleks Se- DAN najbolje ekstrahirati te samim time što točnije odredi količinu selenija u uzorku. Uzorak se razarao uz pomoć koncentriranih kiselina: dušične, sulfatne, perklorne i klorovodične, a kao najbolje otapalo za ekstrakciju Se-DAN kompleksa pokazao se cikloheksan.Aim of this thesis is fluorimetric detection of selenium and determination of its concentration in organic samples. Selenium dosent show fluorescence in any oxidation state, but when bound to specific marker the obtained compound shows fluorescence. 2,3-diaminonaphtalene (DAN) was used as a selenium marker. Reaction of selenium and DAN gives Se-DAN complex, a fluorescent compound. With this method selenium concentration can be determinated. Samples that were analysed were suplement pills containing significant amount of selenium. Beside of finding the best way of digestion, it was important to choose suitable solvent in which Se-DAN complex will be completly extracted. Acuraccy of selenium determination in samples depends on the solvent. In this thesis, different digestion methods (with concentric nitric, sulfate, perchloric and hydrochloric acid) and different extraction solvents were tested. Cyclohexane showed best extraction characteristics
Synthesis and evaluation of fluorescent probe for H2S sensing
No full textSumporovodik () je prvenstveno poznat kao toksin i njegova biološka uloga često nije prepoznata, međutim se javlja u organizmima, od bakterija do sisavaca, kao redoks aktivna signalna molekula, odnosno biološki glasnik. Njegova koncentracija u organizmima iznosi 10-100 μmol/ i povezana je s različitim patološkim procesima. Zbog tako male koncentracije potrebne su novije i osjetljivije metode detekcije. Problem s određivanjem u živim organizmima je brz katabolizam zbog kojeg dolazi do stalne promjene njegove koncentracije i posljedica toga su netočni rezultati. Kao jedno od rješenja tih problema, predlažu se metode bazirane na fluorescenciji. Cilj ovog rada bio je sintetizirati reverzibilno fluorescentno osjetilo za te okarakterizirati dobiveni spoj. Pripravljena su tri konačna produkta: , i , a njihova karakterizacija provedena je FT-IR spektroskopijom i fluorescentnom spektroskopijom. Navedenim metodama utvrđeno je kako je sintezom dobiveno reverzibilno fluorescentno osjetilo za , sinteza se pokazala neuspješnom, a sintezom dobiveno je reverzibilno pH osjetilo, ali ne i osjetilo za .Hydrogen sulfide () is commonly known as a toxin and its biological role is often neglected. is a redox active signal molecule and can be found in different organisms, from bacteria to mammals, where it has a role of a biological messenger. Its concentration in live organisms is 10-100 μmol/ and can be connected with different pathological processes. Hence, the new and more sensitive detection methods are necessary. The main problem when it comes to detection is its fast catabolism, which means that the concentration is constantly changing, giving us the incorrect results. As one of the possible solutions, fluorescence based methods are suggested. The aim of this paper was to synthesize a reversible fluorescent probe for sensing and characterize the compound. Three final products were made: , i , and were characterized using FT-IR spectroscopy and fluorescence spectroscopy. These methods showed that a reversible fluorescent probe for sensing was indeed synthesized (). synthesis wasn't successful and it was shown that the works as a reversible pH probe, but not an probe
Determination of omega - 3 fatty acides
No full textOmega - 3 masne kiseline posebna su skupina nezasićenih masnih kiselina. Često se opisuju kao dragocjene masnoće zato što su jako važne za zdravlje. Ključne su za zdravlje srca i krvnih žila, mozga i zglobova te pozitivno utječu na raspoloženje i pospješuju djelovanje antidepresiva. Omega - 3 masne kiseline su esencijalne, što znači da ih organizam ne može proizvesti i zato se moraju unositi hranom. Najbolji izvori ovih kiselina su masna riba, lanene sjemenke, kanola, soja i orasi. Postoji veliki broj znanstvenih publikacija koje opisuju metode određivanja i analize omega -3 masnih kiselina iz različitih namirnica. To je donijelo veliki napredak u ljudskoj prehrani i očuvanju zdravlja. U eksperimentalnim istraživanjima za izolaciju omega - 3 masnih kiselina iz biljaka ili životinja, uglavnom se koristi ekstrakcija, a najčešće korištene su metode zelene ekstrakcije, tj. ekstrakcija superkritičnim CO2 i druge. Najpopularnije metode analize i detekcije omega - 3 masnih kiselina su kromatografske metode. Najčešće korištena kromatografska metoda je GC - MS metoda koja ujedinjuje plinsku kromatografiju i masenu spektrometriju. Važno je spomenuti da su sve metode određivanja omega - 3 masnih kiselina u daljnjem razvoju i svakim novim istraživanjem znanstvenici žele ostvariti što bolje rezultate.Omega - 3 fatty acids are special group of unsaturated fatty acids. They are oft described as valuable fat because of their importance for human health. They are crucial for heart, blood vessels, brain and joints health. They also positively affect the mood and enhance the antidepressants action. Omega - 3 fatty acids are essential, which means that the organism can´t produce it by itself, and therefore we have to eat more often food that contains omega - 3 fatty acids. The best sources of omega - 3 fatty acids are fish, flax seeds, soya bean, canola and walnuts. There is a large number of scientific publications that describe methods for determination and analysis of omega - 3 fatty acids in different type of groceries. That is a huge step forward in human nutrition and health care. In experimental research extraction is most commonly used for isolation of omega - 3 fatty acids from plants and animals and the most commonly used are green extraction methods, i.e. extraction with supercritical CO2 and others. Most popular methods of analysis and detection of omega - 3 fatty acids are chromatography methods. Mostly used chromatography method is GC - MS method which unites gas chromatography and mass spectrometry. It is important to say that all methods for omega - 3 fatty acids determination are in further development and with each new research scientists want to achieve better results
Determination of selenium concentrations in eggs by inductively coupled plasma atomic emission spectroscopy
No full textU ovom radu bavili smo se mikroelementom selenom. U prirodi ga nalazimo u tragovima. Pravomjernom edukacijom o biogeokemijskom ciklusu kruženja selena kroz elemente i tvari ekosustava pružili smo bolji uvid u njegovu rasprostranjenost, ali i biodostupnost. Nadalje, upoznavanjem fizikalnih i kemijskih svojstava selena i širokog spektra formi u kojima se u prirodi može pojaviti upoznali smo se i s kemizmom selena. Analitička kemija nam pruža uvid u metode analize elemenata. Sofisticiranije metode i uređaji su korišteni kako bismo odredili koncentraciju selena u jajima. Koristili smo metodu induktivno spregnute plazma atomske emisijske spektroskopije zajedno s hidridnom tehnikom kako bismo sa što većom preciznošću došli do rezultata. Rezultati su pokazali da je metoda pogodna za određivanje sadržaja selena u jajima.This paper deals with the microelement of selenium. In nature we find it in traces. By providing proper education about the biogeochemical cycle of circulating selenium through the elements and substances of the ecosystem, we gained a better insight into its distribution and bioavailability. Furthermore, by getting acquainted with the physical and chemical properties of selenium and the wide spectrum of shapes in which nature may appear, we have also become familiar with the chemistry of selenium. Analytical chemistry provides insight into element analysis methods. More sophisticated methods and devices were used to determine the concentration of selenium in eggs. We used the inductively coupled plasma atomic emission spectroscopy method together with the hydride technique in order to achieve as much precision as possible. The results have shown that the method is suitable for determining the content of selenium in eggs
Caspases as target molecules in antitumor drug developoment
No full textKaspaze su proteaze koje u svom aktivnom mjestu sazdrže cistein te cijepaju proteinski supstrat nakon aspartata. Imaju ulogu u raznim staničnim procesima, uključujući apoptozu, diferencijaciju, upalne odgovore i dr.. Kod ljudi je prisutno 12 kaspaza, a dijele se na kaspaze koje sudjeluju u procesu apoptoze i kaspaze uključene u upalnom odgovoru. Kaspaze koje sudjeluju u apoptozi se dijele na kaspaze inicijatore i kaspaze izvršitelje. Iako sudjeluju u mnogim staničnim procesima, u tumorsikim se stanicama kaspaze najčešće povezuju s apoptozom, pri čemu imaju ključnu ulogu u izvršenju stanične smrti. Tumori nastaju nekontroliranom proliferacijom stanica, koja je, među ostalim, uzrokovana upravo gubitkom kontrole stanične smrti. Time dolazi do preživljavanja tumorskih stanica te u konačnici metastaziranja tumora. Novija se istraživanja se usmjeravaju na kaspaze kao ciljne molekule u liječenju tumora, odnosno regulaciju njihova djelovanja kojom bi se pospješila apoptoza u tumorskim stanicama. Upotrebom inhibitora ili aktivatora kaspaza može se utjecati na sudbinu stanice, odnosno na njeno preživljavanje ili smrt. Cilj je pronaći lijek sa što manje nuspojava, bez utjecaja na zdrave stanice.Caspases are a proteases with a conserved cysteine residue at their active site. There enzymes cleave their substrates after an aspartate residue. They have role in various cellular processes, including apoptosis, differentiation and inflammatory responses. Twelve caspases have been identified in humans and are divided into two groups, caspases involved in the process of apoptosis and caspases involved in inflammatory response. Caspases participating in apoptosis are divided into caspases initiators and caspases effectors. Even though, caspases have an effect on many cellular processes, when it comes to tumors, caspases are most commonly associated with apoptosis, having the crucial role inthe execution of cell death. Tumors are caused by uncontrollable cell proliferation, which is usually a result of the loss of cell death control. This results in the survival of tumor cells and, ultimately, tumor metastasis. Current research is directed to caspases as target molecules in cancer treatment or to the regulation of their activity in order to increase apoptosis in tumor cells. Caspase inhibitor or activator can affect the cell fate, survival or its death. The goal is to find a drug with as little side effects as possible and without affecting the healthy cells
Conductors, semiconductors and insulators
No full textU ovom radu bit će riječi o vodičima, poluvodičima te izolatorima odnosno tvarima koje se razlikuju prema sposobnosti provođenja električne struje. Zbog same strukture tvari, vodiči će izuzetno dobro provoditi električnu struju, poluvodiči ovisno o eksperimentalnim uvjetima mogu, a i ne moraju provoditi električnu struju, dok će izolatori pružati izuzetno visok otpor prolasku električne struje. U samom radu će biti i nešto više riječi o primjeni ovih skupina materijala.In this thesis conductors, semiconductors and insulators will be discussed. These materials differ in electrical conductivity. Because of the structure of the materials, the conductors will show very high electrical conductivity, semiconductors, depending on the experimental conditions, may or may not conduct electric current, while the insulators provide exceptionally high resistance to the conductivity of electric current. In this thesis, there will be more words about the application of these groups of materials
Synthesis and indentification of complex compounds of zinc, cobalt and chromium with mixed ligands
No full textCilj završnog rada je sintetizirati i opisati kompleksne spojeve kobalta, kroma i cinka sa miješanim ligandima, derivatom dipikolinske kiseline (6-(2-benzoil hidrazinkarbonil) pikolinska kiselina) i 1,6-diaminoheksanom. Sinteze su rađene u digestoru na magnetskoj mješalici, pri temperaturi oko 40 °C. Metalne soli korištene u sintezi kompleksa su kobaltov(II) klorid heksahidrat, kromov(III) klorid heksahidrat i cinkov(II) nitrat heksahidrat. Svi reaktanti otopljeni su u metanolu, uz dodatak otopine amonijaka i dimetilformamida za poboljšanje topljivosti. Dobiveni produkti analizirani su IR spektroskopijom, termogravimetrijskom analizom i cikličkom voltametrijom, u svrhu dobivanja uvida u njihov sastav i strukturu. Rezultat analiza je pretpostavljena struktura kromovog(III) kompleksa, .The goal of this thesis was to synthesise and describe complex compounds of cobalt, chromium and zinc with mixed ligands, a derivative of dipicolinic acid (6-(2-benzoyl hidrazine carbonyl) picolinic acid) and 1,6-diaminohexane. Syntheses were carried out in a fume hood on a magnetic stirrer, at temperature of approximately 40 °C. Metallic salts which were used in syntheses are cobalt(II) chloride hexahydrate, chromium(III) chloride hexahydrate and zinc(II) nitrate hexahydrate. All reactants were dissolved in methanol, with addition of aqueous ammonia and dimethylformamide to enhance solubility. Analysis of prepared products was conducted by means of IR spectroscopy, thermogravimetric analysis and cyclic voltammetry, so that an insight into their composition and structure could be obtained. As a result, a structure of chromium(III) complex, has been presumed
Determination of cationic surfactants in disinfectants using nanomaterial based electrode
No full textMjeren je sadržaj kationskih tenzida u četiri uzorka komercijalnih dezinfekcijskih sredstava s različitim sadržajem kationskih tenzida: dezinficijens za podove, dezinficijens za radne površine, dezinficijens za ruke i dezinficijens za medicinske instrumente. Sadržaj kationskih tenzida prvo je određivan standardnom metodom za određivanje kationskih tenzida titracijom u dvije faze. Rezultati dobiveni standardnom metodom uspoređeni su s rezultatima dobivenim potenciometrijskom titracijom. Za potenciometrijske titracije korišten je senzor za kationske tenzide sa čvrstim kontaktom i tekućom membranom. Tekuća membrana senzora u svom sastavu je kao senzorski materijal imala višestjenčane ugljikove nanocjevčice (MWCNT) kemijski modificirane cetilpiridinijevim kationom i sulfatnom grupom. Natrijev dodecil sulfat (NaDDS), c = 4· mol/L korišten je kao titrans pri potenciometrijskim titracijama. Kako bi provjerili točnost i preciznost određivanja potenciometrijskim titracijama, upotrijebljena je metoda standardnog dodatka. Kao standardni dodatak korištena je otopina cetilpiridinijevog klorida (CPC) c = 4· mol/L. Rezultati dobiveni potenciometrijskom titracijom, iako nešto niži od vrijednosti dobivenih standardnom metodom, pokazali su zadovoljavajuće slaganje s rezultatima koji su dobiveni standardnom metodom. Provjera točnosti i preciznosti određivanja potenciometrijskim titracijama metodom standardnog dodatka, pokazala je dobru točnost i preciznost. Postotak iskorištenja je bio u rasponu od 93,9 % do 107,6 % što se podudara s kriterijem prihvatljivosti (90-110%). Potenciometrijskom titracijom uspješno je određen sadržaj kationskih tenzida u komercijalnim uzorcima dezinfekcijskih sredstava. Sadržaj tenzida je bio u rasponu od 0,27 % do 44,26 % što pokazuje da se elektroda može uspješno koristiti za određivanja širokog raspona sadržaja kationskih tenzida u realnim uzorcima.The content of cationic surfactants was measured in four samples of commercial disinfectants with different amount of cationic surfactants: floor disinfectants, surface disinfectants, hand disinfectants and disinfectants for medical instruments. The amount of cationic surfactants was first determined by the standard two phase titration method. The results acquired by the standard method were compared with the results acquired by potentiometric titration. For potentiometric titrations, a sensor for cationic surfactants with solid contact and polymer liquid membrane was used. The liquid membrane of the sensor as a sensing material had a multiwalled carbon nanotubes (MWCNT) chemically modified by cetylpyridinium cation and a sulfate group. Sodium dodecyl sulfate (NaDDS), c = 4· mol/L was used for potentiometric titration of cation surfactant. In order to validate the precision and accuracy of potentiometric titration determination, the standard addition method was used. Solution of cetylpyridinium chloride (CPC) c = 4 · mol/L was used as the added standard. The results acquired by potentiometric titration, although lower than the values acquired by the standard method, showed satisfactory agreement with the results acquired by the standard method. Verification of accuracy and precision of potentiometric titrations by the standard addition method showed good accuracy and precision. The percentage of recovery ranged from 93.9 % to 107.6%, which corresponds to the eligibility criteria (90-110%). Potentiometric titration was successfully used for determination of cationic surfactants in samples of commercial disinfectants. The content of cationic surfactant ranged from 0.27 % to 44.26 %, which indicates that the electrode can be successfully used to determine the wide range of cationic surfactants in real samples