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Phenols and Quinones
No full textAromatski spojevi su cikličke, potpuno konjugirane, planarne molekule s odgovarajućim, točno određenim brojem π elektrona. U ovom radu opisani su aromatski spojevi te njihove karakteristične reakcije. Fenoli i kinoni čine veliku skupinu organskih spojeva s raznolikom ulogom. Fenoli su aromatski spojevi s vezanom hidroksilnom skupinom na aromatski prsten, dok su kinoni spojevi dobiveni iz aromatskih spojeva, no sami nisu aromatični. Kinoni pripadaju skupini nearomatskih konjugiranih cikloheksadienona pa se i promatraju kao α,β-nezasićeni spojevi. U radu su objašnjena svojstva navedenih spojeva, njihove reakcije, sinteze te primjena u svakodnevnom životu kao i njihov biološki značaj.Aromatic compounds are cyclic, fully conjugated, planar molecules with a specific number of π electrons. This thesis elaborates aromatic compounds and their characteristic reactions. Phenols and quinones represent a class of organic compounds with various role. Phenols are aromatic compounds containing a hydroxy group bonded to an aromatic ring, while quinones are derivated from aromatic compounds, but aren't aromatic compounds themselves. Quinones represent a group of non-aromatic conjugated cyclohexadienones and therefore are observed as α,β-unsaturated compounds. This thesis also elaborates phenols and quinones, their reactions, synthesis and uses, but also their biological importance
Equilibriums at phase boundary
No full textKako u homogenim tako i u heterogenim sustavima, pri određenim uvjetima nakon nekog vremena, dolazi do uspostave ravnoteže. Promatramo li heterogene ravnoteže samo s gledišta broja faza i komponenata govorimo o faznim ravnotežama. U ovom radu opisane su ravnoteže na granici faza čvrsto-tekuće, tekuće-plinovito, čvrsto-plinovito. Opisane su i ostale granice prijelaza kao i fazne promjene koje ih prate te fazni dijagram vode i smjese vode i etanola. Uz to je opisana i njihova primjena te primjeri u svakodnevnom životu.Under certain conditions and after a while, equilibrium is established in both homogeneous and heterogeneous systems. By observing number of phases and components of heterogeneous equilibrium we talk about phase equilibriums. In this thesis equilibrium at solid-liquid, liquid-gaseous and solid-gaseous phase boundary is described. Other phase transition boundaries, the phase changes and phase diagrams of water and mixture of water and alcohol are also described. In addition, aplication and examples in real life are also described
Metal complexes of carnosine
No full textU ovom radu ispitivana su elektrokemijska i spektrofotometrijska svojstva β-alanina, L-histidina i L-karnozina koncentracije, c = 1∙ mol te stvaranje kompleksa navedenih spojeva s bakrom u omjerima 1:1, 2:1, 4:1, 1:2 i 1:4 u puferu pH = 10. Cilj rada bio je ispitati stvaranje kompleksa β-alanina, L-histidina i L-karnozina s dvovalentnim bakrovim ionom, u puferu pH = 10, odrediti omjer pri kojem nastaju kompleksi, istražiti utjecaj brzine promjene polarizacije elektrode na oksido-redukcijska svojstva kompleksa, istražiti moguću adsorpciju oksidacijskog produkta na površinu radne elektrode. Elektrokemijska svojstva ispitivana su pomoću potenciometrijske titracije te cikličke i diferencijalno pulsne voltametrije, a spektrofotometrijska pomoću UV/VIS spektrofotometrije. Elektrokemijska ćelija za potenciometrijska mjerenja sadržavala je platinsku indikatorsku elektrodu. U otopinu analita (β-alanin, L-histidin ili L-karnozin) dodavala se otopina bakrova nitrata, a završna točka titracije određena je instrumentalno. Za voltametrijska mjerenja koristio se troelektrodni sustav s radnom elektrodom od staklastog ugljika. Potenciometrijskom titracijom utvrđeno je da L-histidin i L-karnozin tvore kompleks s bakrovim ionom u omjeru 1:1 u puferu pH = 10. Ciklička voltametrija pokazala je da β-alanin, L-histidin i L-karnozin nisu elektroaktivni te da dolazi do stvaranja kompleksa između L-histidina i bakrovog iona te L-karnozina i bakrovog iona već u omjeru 1:1 kao i da je proces koji se odvija na površini radne elektrode difuzijski kontroliran. Diferencijalnom pulsnom voltametrijom potvrđeno je nastajanje kompleksa L-histidina i L-karnozina s bakrovim ionom u puferu pH = 10, utvrđeno je da su L-histidin i L-karnozin elektroaktivni te da ne dolazi do adsorpcije L-histidina i L-karnozina te njihovih kompleksa s bakrovim ionom na radnu elektrodu od staklastog ugljikaIn this work electrochemical and spectrometric properties of β-alanine, L-histidine and L-carnosine concentration, c = 1∙ mol as well as complexation of those compounds with copper in ratio 1:1, 2:1, 4:1, 1:2 and 1:4 prepared in buffer pH = 10 were studied. Main purpose of this thesis was to examine complexation of β-alanine, L-histidine and L-carnosine with divalent copper ion, in buffer pH = 10, determine ratio of complexation, investigate influence of the scan rate on the oxido-reduction properties of complexes, study possible adsorption of oxidation product on the surface of the working electrode. Electrochemical properties were investigated by potentiometric titration, cyclic voltammetry and differential pulse voltammetry, while spectrometric with UV/VIS spectrometry. Electrochemical cell for potentiometric measurements was consisted of platinum indicator electrode. Solution of copper nitrite was added in solution of analyte (β-alanine, L-histidine, L-carnosine) and equivalent point was determined instrumentally. Three electrode system with glassy carbon working electrode was used for voltammetric measurements. It was found by potentiometric titration that L-histidine and L-carnosine form complex with copper ion in ratio 1:1 in buffer pH = 10. Cyclic voltammetry showed that β-alanine, L-histidine and L-carnosine were not electroactive and also that there is complexation among L-histidine and copper ion as well as L-carnosine and copper ion from ratio 1:1. Likewise measurements showed that process which undergoes on working electrode is diffusion controlled. Complexation of L-histidine and L-carnosine with copper ion in buffer pH = 10 was confirmed by differential pulse voltammetry as well as that L-histidine and L-carnosine were electroactive and that there was not undergone adsorption of L-histidine, L-carnosine and its complex with copper ion on glassy carbon working electrode
Determination of DNA Concetration from Samples of Human and Plantal Origin
No full textU ovome radu određena je koncentracija DNA u biljnom uzorku odnosno bosiljku (lat.Ocimumbasilicum) i HeLa stanicama pomoću UV-VIS spektrofotometra i Nanofotometra. Izolirana DNA je vizualizirana primjenom elektroforeze na agaroznom gelu. Utvrđeno je da je Nanofotometar prikladniji uređaj za određivanje koncentracije DNA, a bolje rezultate pokazuje uzorak HeLa stanica, jer je teže izolirati DNA iz biljke. Također, proces izolacije je dug što produljuje cjelokupan postupak određivanja koncentracije DNA. Opisan je i metodički dio na temu "Nukleinske kiseline" za srednju školu, koji sadrži pisanu pripremu za nastavni sat, radni listić, te jedan pokus. Nakon što učenici samostalnim izvođenjem predviđenog pokusa u 3 skupine dođu do određenih zaključaka, predviđeno je frontalno predavanje kao zaključak na izvedene pokuse.In this thesis, concentration of DNA in the basil plant sample (lat. Ocimum basilicum) and HeLa cells was determined by UV-VIS spectrophotometer and Nanophotometer. Isolated DNA was visualized using agarose gel electrophoresis. Obtained results have revealed that Nanophotometer is more suitable device for determining DNA concentration. HeLa cells sample shows better results because DNA from plants are harder to isolate. Also, the process of isolation is long which elongates the whole procedure of determining DNA concentration. This thesis also contains a part with teaching methods on highschool level including printed preparation for lesson on "Nucleic acids", corresponding working papersand one experiment for group work. After students divided into 3 groups experimentally come to certain conclusions, there is a lecture predicted as a conclusion on experiments
Influence of interference on the surfactant electrode properties
No full textCilj ovog diplomskog rada je proučiti utjecaj različitih interferenata anionskih tenzida i neionskih tenzida na karakteristike tenzidne grafitne elektrode s nanocjevčicama (CNTSS) - karakteristike odziva CNTSS na anionske tenzide i njihove karakteristične titracijske krivulje; te upotreba CNTSS za određivanje anionskih tenzida u komercijalnim uzorcima. CNTSS u sastavu senzorske membrane ima i ugljikove nanocjevčice, koje povećavaju kontaktnu površinu i prijenos naboja između analita i elektrode, te smanjuju otpor membrane i omogućavaju stabilniji signal. Komercijalni proizvodi za pranje osim tenzida, sadrže i niz drugih komponenti, kao što su anorganske soli i neionski tenzidi, koji mogu djelovati interferirajuće na karakteristike odziva CNTSS. Metoda fiksnih interferenata korištena je za određivanje koeficijenta selektivnosti različitih anionskih interferenata koji se nalaze u formulacijama komercijalnih proizvoda, mjerenjem utjecaja fiksne koncentracije interferenta na odziv CNTSS na anionski tenzid. Neionski tenzidi sadrže različiti broj etoksi grupa, a upravo broj etoksi grupa utječe na karakteristike titracijske krivulje, odnosno uspješnost određivanja tenzida potenciometrijskom titracijom. U radu je ispitan utjecaj različitog broja etoksi skupina na karakteristike potenciometrijske titracije, te utjecaj omjera anionskog tenzida i odabranog neionskog tenzida na karakteristike potenciometrijske titracije. Komercijalni uzorci proizvoda s anionskim tenzidima određivani su pri pH 3. U metodičkom dijelu rada je nastavna jedinica "Sapuni i detergenti" za 4. razred gimnazije s ciljem upoznavanja njihove strukture i svojstava te primjene u svakodnevnom životu. Nastavni sat uključuje obradu novog gradiva, pokuse i radne listiće.The aim of thesis is to examine the influence of various anionic interferers and nonionic surfactants on the characteristics of the tenside graphite electrode with carbon nanoparticles (CNTSS) - response characteristics of CNTSS for anionic surfactants and titration curves; and using of CNTSS to determine anionic surfactants in real commercial samples. The sensor membrane consists of carbon nanoparticles, which increase the contact surface and charge between the analyte and electrode and reduce the membrane resistance and provide a more stable signal. Commercial washing products also contain a number of other components, such as inorganic salts and nonionic surfactants, which may interfere with the CNTSS response characteristics. Fixed interference method was used to determine the selectivity coefficient of various anions found in commercial product formulations by measuring the influence of the fixed concentration of interfering ion on the response of CNTSS towards anionic surfactant. Nonionic surfactants contain a different number of ethoxy groups, where the number of ethoxy groups has a direct influence on the characteristics of the titration curve, i.e. the performance of the surfactant by potentiometric titration. The effect of different number of ethoxy groups on the potentiometric titration characteristics and the influence of the ratio of anionic surfactant and selected nonionic surfactant to the potentiometric titration characteristics have been studied. The anionic surfactants content in commercial samples were determined at pH 3. In the methodological part of the work, the teaching unit "Soaps and Detergents" for the 4th grade of grammar school aims to get acquainted with their structure and properties and their application in everyday life. The lesson includes the processing of new material, experiments and job listings
Porous materials
No full textPorozni materijali i njihova važnost su nam poznati od davnina. Istraživanje započinje otkrićem zeolita švedskog mineraloga Freiherr Axel Fredrick Cronstedta 1756. godine. Zbog svojih specifičnih svojstava pronalaze sve veću ulogu u svakodnevnom životu. Sve bolja osviještenost ljudi o onečišćenju i zaštiti okoliša, kao što je uklanjanje odnosno selektivno vezanje štetnih plinova iz okoliša, potaklo je sve veće zanimanje u primjeni i razvoju poroznih materijala. Sam koncept poroznih materijala koristi se u mnogim područjima inženjerstva i znanosti (naftni inženjering, građevini, hidrogeologiji, geofizici ,strojnoj mehanici, biologiji, biofizici, elektrokemiji, petrokemiji ...). Porozne materijale možemo definirati kao materijale koji imaju pore. Postoji veliki broj različitih poroznih materijala, ali svi imaju zajednička svojstva i karakteristike. U ovom radu opisana je sinteza makrocikličke Schiffove baze. Dobiveni produkt okarakteriziran je infracrvenom spektroskopijom i termogravimetrijskom analizom.Porous materials and their importance have been known to us since ancient times. The exploration begins with Swedish mineralogist Freiherr Axel Fredrick Cronstedt who disccovered zeolites in 1756. Because of their specific properties they find an ever increasing role in everyday life. Better awareness of pollution and environmental protection, such as the removal or selective coupling of harmful gases from the environment, has attracted a growing interest in the application and development of porous materials. The concept of porous materials is used in many fields of engineering and science (petroleum engineering, construction, hydrogeology, geophysics, machine mechanics, biology, biophysics, electrochemistry, petrochemicals ...). Porous materials can be defined as materials having pores. There are a large number of different porous materials, but all have common properties and characteristics. This paper describes the synthesis of macrocyclic Schiff base. The product obtained was characterized by infrared spectroscopy and thermogravimetric analysis
Comparision of the vitamin C content in fresh, cooked and frozen fruits and vegetables
No full textVitamin C je prirodni organski spoj, vitamin topljiv u vodi, a nalazi se uglavnom u voću i povrću. Potreban je organizmu za sintezu kolagena i karnitina, u metabolizmu masnih kiselina, jaki je antioksidans, a kako ga ne moţemo sami proizvesti moramo ga unositi hranom. Najčešći unos vitamina C je preko hrane, a kod manjka (hipovitaminoze) moţe se unositi u obliku šumećih tableta, praha ili soka kao dodatka prehrani. Izraziti manjak vitamina C dovodi do bolesti koja se zove skorbut. Vitamin C poznat je i po svom učinku na imunološki sustav te se zbog toga preporućuje konzumacija voća i povrća bogatog vitaminom C kod različitih bolesti (gripa, prehlada i dr.). Najviše vitamina C prisutno je u svjeţem voću i povrću, a obrada hrane utječe na njegovu količinu u namirnici zbog toga što je topiv u vodi pa se ispire te je osjetljiv na svjetlost, oksidira na zraku, nestabilan je pa se gubi skladištenjem, kuhanjem ili zamrzavanjem. U ovom radu odreĎene su količine vitamina C u svjeţem, kuhanom i zamrznutom voću i povrću te su usporeĎene dobivene vrijednosti kako bi se utvrdio najbolji način za konzumiranje namirnica bogatih vitaminom C.Vitamin C is an natural organic compound. It is water soluble vitamin which can be found in fruits and vegetables. Human body uses vitamin C for synthesis of collagen and carnitine, in fatty acid synthesis and it is also very strong antioxidant. Humans can not produce it so it must be consumed. Eating fruits and vegetables usually provides enough vitamin C, but in case of vitamin C deficiency (hypovitaminosis) it can be consumed in the form of effervescent tablets, powder or juice as dietary supplement. Vitamin C deficiency leads to scurvy disease. Benefits of this vitamin includes protection against immune system deficiencies and it is recommended to eat fruits and vegetables with this vitamin during the flu and similar diseases. Fresh fruits and vegetables contain the biggest amount of vitamin C. Food processing has effect on this because vitamin C is water soluble, light sensitive, easy to oxidize and it loses when stored, cooked or frozen. In this paper amounts of vitamin C are determined in fresh, cooked and frozen fruits and vegetables. Obtained values are comparised in order to determine the best way for consuming groceries with vitamin C
Measurement methods of antioxidant activity
No full textAntioksidansi su spojevi koji pokazuju veliku aktivnost u sprječavanju štetnog djelovanja slobodnih radikala. Za mjerenje antioksidativne aktivnosti spojeva služe nam različite metode među koje ubrajamo spektrometrijske, elektrokemijske i kromatografske metode. Kao ostale metode opisane su biosenzorska metoda, fluorimetrija i elektronska spinska rezonancija. U spektrometrijskim metodama, antioksidans donira vodik radikalu ili radikalskom kationu, te na taj način reagira s njim. U ovom radu objašnjene su DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)), FRAP (ferric reducing antioxidant power), ORAC (oxygen radical absorption capacity), HORAC (hydroxyl radical averting capacity), TRAP (total peroxyl radical trapping antioxidant parameter), PERAP (potassium ferricyanide reducing power) i CUPRAC (cupric reducing antioxidant power) (2,2-difenil-l-pikirhidrazil) spektrometrijske metode. Elektrokemijske metode se temelje na mjerenju intenziteta struje i potencijala radne elektrode. Ciklička voltametrija, amperometrija i biamperometrija opisane su kao najznačajnije elektrokemijske metode. Kromatografske metode temelje se na razdvajanju spojeva između stacionarne i mobilne faze iz smjese spojeva, nakon čega se antioksidativni kapacitet spojeva određuje spektrofotometrijskom metodom. U ovom radu objašnjene su plinska i tekućinska kromatografija visoke djelotvornosti (HPLC). Biosenzori se primjenjuju za određivanje antioksidansa u čijem istraživanju je uključeno praćenje superoksidnog radikala, dušikovog oksida, glutationa, urične kiseline, askorbinske kiseline ili fenolnih spojeva, a za mjerenje ukupne antioksidativne aktivnosti koriste se DNA biosenzori. Fluorometrija je metoda koja se temelji na fluorescenciji, a antioksidativni kapacitet spojeva se određuje mjerenjem fluorescencijskog i emisijskog spektra pomoću spektrofotometra. Elektronska spinska rezonancija je metoda koja se koristi za proučavanje slobodnih radikala i paramagnetskih metala u kemijskim i biološkim tkivima.Antioxidants are compounds that show great activity in preventing the harmful effects of free radicals. To measure the antioxidant activity of the compounds, different methods are used, which are spectrometric, electrochemical and chromatographic ones. As other methods, the biosensor method, fluorimetry and electron spin resonance are described. In spectrometric methods, the antioxidant donates hydrogen to the radical or radical cation and thus react with it. This paper explains DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS ( 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)), FRAP (ferric reducing antioxidant power), ORAC (oxygen radical absorption capacity), HORAC (hydroxyl radical averting capacity), TRAP (total peroxyl radical trapping antioxidant parameter), PERAP (potassium ferricyanide reducing power) and CUPRAC (cupric reducing antioxidant power) spectrometric methods. Electrochemical methods are based on measuring the intensity of the current and the potential of the working electrode. Cyclic voltammetry, amperometry and biamperometry are described as the most important electrochemical methods. Chromatographic methods are based on the separation of the compounds between the stationary and the mobile phase from the mixture of compounds, after which the antioxidant capacity of the compounds is determined by spectrophotometric method. This paper describes high-resolution gas and liquid chromatography (HPLC). Biosensors are used to determine the antioxidants in which a superoxide radical, nitrogen oxide, glutathione, uric acid, ascorbic acid or phenolic compounds is monitored, and DNA biosensors are used to measure total antioxidant activity. Fluorimetry is a method based on fluorescence, and the antioxidant capacity of the compounds is determined by measuring the fluorescence and emission spectra by spectrophotometers. Electron spin resonance is a method used to study free radicals and paramagnetic metals in chemical and biological tissues
The aspartame and its toxicity
No full textAspartam je metilni ester dipeptida koji se sastoji od asparaginske kiseline i fenilalanina. Postoje 2 oblika aspartama, oblik a i b, a samo je oblik a sladak. On je otprilike 200 puta slađi od saharoze. Upotreba aspartama odobrena je u širokom rasponu prehrambenih proizvoda (više od 6000), u 90 zemalja diljem svijeta. Aspartam je predmet brojih studija kancerogenosti. Otkrio ga je 1965. godine kemičar James M. Schlatter, kada je testirao lijek protiv čira te tako otkrio sladak okus tog spoja.Aspartame is a methyl ester dipeptide which consists of aspartic acid and phenylalanine. There are two forms of aspartame, form a and form b, but only a form is sweet. It is approximately two hundred times sweeter than sucrose. Usage of aspartame is approved widely in nutritional products in more than six thousand products in ninety countries world wide. Aspartam is a subject of many studies of cancerogenicity. It has been discovered by chemist James M. Schlatter in 1965. when he tested drug for gastric ulcer and discovered sweet taste of this product
Sensonal variations of benzene concentrations in the air of Nature park Kopački rit
No full textBenzen je značajna industrijska kemikalija i sveprisutan je u čovjekovom okruženju. U prirodi nastaje fotokemijskom razgradnjom ugljikovodika te emisijom antropogenog i biogenog podrijetla. U Kopačkom ritu benzen se počeo kontinuirano mjeriti 2015. godine. Kako bi se procijenilo postoje li značajne razlike u vrijednostima koncentracije benzena od ranije izmjerenih vrijednosti analizirane su koncentracije benzena mjerene na području Kopačkog rita 2015. i 2016. godine. Nadalje, analizirane su koncentracije benzena u odnosu na koncentracije ozona i meteorološke parametre. Prosječne dnevne vrijednosti koncentracije benzena nisu prešle granične vrijednosti propisane Zakonom o zaštiti zraka (5 μg/m³). Veće vrijednosti koncentracije benzena izmjerene su tijekom zimskog perioda, a uzrok tomu mogu biti fotokemijske reakcije. Rezultati za obje promatrane godine ukazuju na pozitivnu korelaciju između relativne vlažnosti zraka i atmosferskog tlaka te na negativnu korelaciju između temperature zraka, koncentracije ozona i rosišta. Metodički dio diplomskog rada sadrži pripremu za nastavnu jedinicu "Aromatski ugljikovodici" s ciljem upoznavanja njihove strukture i svojstava te primjene u svakodnevnom životu. Priprema za nastavni sat uključuje obradu novog gradiva, demonstracijski pokus kojim će biti prikazana svojstva benzena te radni listić.Benzene is an important industrial chemical and is often present in the human environment. It is formed in nature through hydrocarbon degradation as well as anthropogenic and biogenic emission. In Kopački rit, benzene is measured continuously from 2015. In order to assess whether there are any significant differences in the benzene concentration values from the previously measured ones, the benzene concentrations measured in the Kopački rit area in 2015 and 2016 were analysed. Furthermore, benzene concentrations were analysed in relation to the concentration of ozone and meteorological parameters. On a daily basis, an average level of benzene concentration did not exceed the limiting value as prescribed by the Law on Protection of Air (5 μg/m³). The higher values of the benzene concentration have been recorded during the winter period the cause of which might be photochemical reactions. The results for both of the observed years indicate a positive correlation between relative humidity and atmospheric pressure and a negative correlation between air temperature, ozone concentration and dew point. Methodic part of graduation thesis contains preparation for the teaching unit "Aromatic hydrocarbons" with an objective of getting acquainted with the composition of aromatic hydrocarbons, their properties and applications in everyday life. Preparation for lesson includes processing of new materials, a demonstration to show some properties of benzene and a worksheet