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Host-Guest Complexes
No full textSupramolekulska kemija definirana je kao "kemija molekularnih sustava i intermolekulskih veza" ili jednostavnije kao "kemija iznad molekule". Ona je "mlada" znanstvena disciplina koja se počela značajnije razvijati krajem 1960-ih i početkom 1970-ih godina prošlog stoljeća. Supramolekulska kemija je multidisciplinarno područje sa središtem proučavanja međumolekulske interakcije i supramolekulskih agregata čija je gradivna jedinica molekula ili molekulska vrsta. Supramolekulski agregat je vrsta koju na okupu drže nekovalentne interakcije između dva ili više kovalentno povezanih molekula ili iona. Može se podijeliti u dvije široke kategorije: domaćin-gost kemija i molekulsko samoudruživanje ili samorganizacija. U ovom radu detaljnije će se opisati domaćin-gost kemija i pripadajući spojevi. Domaćin je najčešće molekula koja posjeduje konvergentnu centralnu šupljinu određene veličine. Gost može biti kation, jednostavni anorganski anion, ionski par ili sofisticiranija molekula poput hormona, feromona ili neurotransmitera koji posjeduje divergentno vezujuće mjesto. Domaćin-gost kompleksi kreću se od vrlo jednostavnih (klorov hidrat, metanski klatrat) do puno složenijih (ciklodekstrin, zeoliti, metal-organske mreže) struktura koje objedinjuju organsku i anorgansku kemiju zajedno s biokemijom, nanotehnologijom i kemijskim inžinjerstvom. Supramolekulska kemija, a samim time i domaćin-gost kemija, razvija se ubrzano tijekom ovih 30 i više godina. Danas je karakterizira širok raspon i raznolikost spojeva koji su primjenjivi u biokemijskim, farmaceutskim, ekološkim, kozmetičkim, prehrambenim i mnogim drugim industrijama te ima još puno prostora za napredak.Supramolecular chemistry is defined as the "chemistry of molecular systems and intermolecular connections" or simply as "chemistry above the molecule". It is a "young" scientific discipline that began to develop significantly in the late 1960s and early 1970s. Supramolecular chemistry is a multidisciplinary field with the focus on intermolecular interactions and supramolecular aggregates whose building blocks are molecules. The supramolecular aggregate is a compound which is held by non-covalent interactions between the two or more covalently linked molecules or ions. It can be divided into two broad categories: host-guest chemistry and self-assembly or molecular self-organization. In this paper more detailed description will be given of host-guest chemistry and related compounds. The host is most often a molecule possessing a convergent centered cavity of a certain size. A guest can be a cation, a simple inorganic anion, an ion pair, or a sophisticated molecule such as a hormone, a pheromone or a neurotransmitter possessing a divergent binding site. The host-guest complexes range from very simple (chlorine hydrate, methane clathrate) to much more complex (cyclodextrin, zeolites, metal-organic framework) structures that combine organic and inorganic chemistry together with biochemistry, nanotechnology and chemical engineering. Supramolecular chemistry, and therefore the host-guest chemistry, is developing rapidly over these 30 years and over. Today, it is characterized by a wide range and variety of compounds that are applicable in biochemical, pharmaceutical, ecological, cosmetic, nutritional and many other industries and there is still plenty of room for improvement
Investigating potential use of eutectic solvents as a substitute for standard organic solvents in SN2 reactions
No full textU svrhu istraživanja ekološki prihvatljive alternative standardnim organskim otapalima u SN2 reakcijama, u ovome je radu ispitana mogućnost primjene eutektičkih otapala kao pogodnog medija u reakcijama kvaternizacije. Stoga su izvedene reakcije kvaternizacije nikotinamida s tri različito supstituirana 2-bromacetofenona. Reakcije su provedene konvencionalnom, mikrovalnom i ultrazvučnom sintetskom metodom. Provedeno istraživanje pokazalo je da su najpogodnija eutektička otapala na bazi kolin-klorida, kao akceptora vodikove veze, i uree, glicerola, acetamida i levulinske kiseline u molarnom omjeru 1 : 2, kao donora vodikove veze. Uporabom mikrovalnog zračenja i ultrazvuka znatno je skraćeno vrijeme reakcija, a konačna iskorištenja povećana su u odnosu na konvencionalnu metodu sinteze.In this study, the possibility of using eutectic solvents as a suitable medium in quaternization reactions was examined to investigate an environmentally friendly alternative to standard organic solvents in SN2 reactions. Therefore, quaternization reactions of nicotinamide were performed using three differently substituted 2-bromoacetophenones. Reactions were conducted using a conventional, microwave and ultrasonic synthetic method. Research has shown that the most suitable eutectic solvents are based on choline-chloride, as hydrogen bond acceptor, and urea, glycerol, acetamide and levulinic acid in a molar ratio of 1: 2, as hydrogen bond donors. The use of microwave radiation and ultrasound significantly reduced reaction time, and final yields were increased in comparison to the conventional synthesis method
Synthesis and reactions of carbenes
No full textKarbeni su neutralne molekule koje sadrže dvovalentni ugljikov atom sa samo šest elektrona u njegovoj valentnoj ljusci, a najjednostavniji karben je metilen ( ). Kratkog su vijeka trajanja i međutim poznati su i stabilni karbeni. Ovisno o broju elektrona u valentnim ljuskama, odnosno o njihovom rasporedu u istima karbene dijelimo na singletne i tripletne. Singletni karbeni su karbeni koji u svojoj strukturi imaju ugljikov atom u hibridiziranom stanju dok tripletni imaju ugljikov atom u sp hibridiziranom stanju. U singletnim karbenima jedna hibridna orbitala sadrži dva nevezna elektrona koji imaju antiparalelni spin, a u tripletnim karbenima elektroni su raspodijeljeni u dvije orbitale. Tripletni i singletni karbeni se također razlikuju i po reaktivnosti. Dok singletni karbeni uglavnom sudjeluju u pericikličkim reakcijama kao elektrofili ili nukleofili, tripletni karbeni se smatraju diradikalnima i sudjeluju u postepnim radikalnim adicijama. Specifične reakcije za karbene su umetanje u C-H vezu, umetanje u O-H ili N-H vezu, ciklopropaniranje te dimeriziranje karbenima. Reakcije kojima dobivamo karbene su raspadanje diazokarbonilnih spojeva, α eliminacija i termalna raspadanje preko hidrazonijevih spojeva.Carbenes are neutral molecules that contain carbon atom with a valence of two with only six electrones in their valent shell. Simplest carbene is methylene ( ). They are short living spicies but there are some carbenes that are stable. Regarding the number of the electrones in valent shells, carbenes can be clasified as singlet or triplet carbenes. In singlet state carbon atom is in hybridisation state. One of hybrid orbital contains unshared electron pair with opposite spins & two hybrid orbitals form two covalent bonds. In triplet carbenes carbon atom is in hybridisation state. Two nonbonding electrons occupy an atomic orbital & an unhybridized p-atomic orbital with parallel spin. Specific reactions for carbenes are insertion into C-H bond, insertion into O-H or N-H bond, cyclopropanation and carbene dimerization. Carbenes can be prepared bz decomposition of diazocarbonyl compounds, α elimination and thermal decomposition through hydrazone compounds
Investigation of response characteristics of the sensor with functionalized carbon nanotubes to anionic surfactants
No full textTenzidi su spojevi koji smanjuju površinsku napetost otopine u kojoj se nalaze, a sastavljeni su od polarnih i nepolarnih dijelova, odnosno hidrofilnih i hidrofobnih. Postoje četiri glavne kategorije tenzida: anionski, kationski, neionski i amfoterni. Anionski tenzidi su površinski aktivne tvari koje imaju negativno nabijenu hidrofilnu skupinu. Čine 70 - 75% ukupne svjetske potrošnje površinski aktivnih tvari te su najčešće korištena klasa tenzida koja se primjenjuje za čišćenje. Potenciometrija se vrlo često koristi za određivanje koncentracije tenzida na način da se mjeri razlika potencijala između elektroda elektrokemijske ćelije uz ravnotežne uvjete. U ovom radu ispitan je odziv potenciometrijskog senzora s ugljikovim nanocjevčicama na anionske tenzide natrijev dodecilsulfat (NaDDS) i natrijev dodecilbenzensulfonat (NaDBS) u ultračistoj vodi u koncentracijskom području od 2,5· M do 5,0· M. Mjerenja su se vršila pomoću indikatorske elektrode s čvrstim kontaktom u čiju je membranu ugrađen senzorski materijal s tetrafenilboratom (TPB) i višestjenčanim ugljikovim nanocjevčicama (MWCNT, eng. multi-walled carbon nanotubes) kovalentno modificiranim kvaternim amonijevim kationom.Surfactants are compounds that reduce the surface tension of the solution in which they are contained and they are composed of polar and non - polar parts, that is hydrophilic and hydrophobic. There are four major categories of surfactants: anionic, cationic, nonionic and amphoteric. Anionic surfactants are surfactants that have a negatively charged hydrophilic group. They represent 70 - 75% of the world's total surfactant consumption and are the most commonly used surfactant class used for cleaning. Potentiometry is very often used to determine the surfactant concentration by measuring the potential difference between electrochemical cell electrodes under equlibrium conditions. In this study, the response of a potentiometric sensor with carbon nanotubes to the anionic surfactants sodium dodecyl sulfate (NaDDS) and sodium dodecylbenzenesulfonate (NaDBS) in ultra pure water was investigated in a concentration range between 2,5· M and 5,0· M. Measurements were made using a solid state indicator electrode with membrane containing sensor material composed of a tetraphenylborate (TPB) and multi - walled carbon nanotubes (MWCNTs) covalently modified by quaternary ammonium cation
Synthesis and characterization of Schiff bases derived from aminobenzoic acids
No full textSupstituiran imin zove se Schiffova baza, koja strukturno, dušični je analog aldehida ili ketona u kojem je karbonilna skupina ( C=O ) zamijenjena iminskom skupinom (C=N) , dvostruka veza ugljik-dušik. Sinteza Schiffove baze reverzibilna je reakcija, u kojoj se kao reaktanti mogu koristiti dialdehidi i aminobenzojeve kiseline. Efikasnost ovakve reakcije kontrolirana je pomoću dva glavna čimbenika koji imaju velik utjecaj na iskorištenje. Koncentracija kiseline ne bi smjela biti prevelika ( pH između 4 i 5 ), potrebni su blago kiseli uvjeti u kojima dolazi do gubitka vode, u suprotnom , ako je otopina prekisela , dolazi do protoniranja amina , što inhibira prvi stupanj - reakcija se ne može nastaviti. Dialdehidi organski su spojevi koji nastaju reakcijama intermolekularne kondenzacije i reakcijama polimerizacije. Sadrže dvije aldehidne grupe i u reakcijama s aminobenzojevim kiselinama tvore dvostruku C=N vezu na obje skupine. Sintetizirati ih možemo iz aldehida i dugolančanih halogenalkana pri određenim uvjetima reakcije ( visokoj temperaturi uz etanol kao otapalo ). Aminobenzojeve kiseline organski su kod kojih je amino skupina - vezana na benzenski prsten benozjeve kiseline na tri različita mjesta. Postoje tri izomera aminobenzojevih kiselina, a to su oroto-aminobenzojeva kiselina, meta-aminobenzojeva kiselina i para-aminonezojeva kiselina. Upotrebom kiselog medija dolazi do deporotoniranja dušika aminoskupine ovih izomera , te on reagira s karbonilinom skupinom dialdehida i nastaje imino dvostruka C=N veza. IR spektroskopija daje nam podatke o vibracijskim vezama čime se dokazuje prisutnost funkcijskih skupina. Temelji se na apsorpciji svjetlosti infracrvenog zračenja pri čemu se mjeri količina zračenja koju spoj apsorbira u ovisnosti o valnoj duljini. Infracrveni spektrometar temeljen na Fourireovoj transformaciji ( FT-IR) koristi se interferometrom za dobivanje spektra, u kojem su sadržane sve važne informacije. Spektar Schiffovih baza pokazuje vibracije istezanja veze C=N ( imino skupine ) u rasponu od 1680-1600 . Spektar je uspoređen sa spektrom dialdehida i aminobenojevim kiselinama.The substituted imine is called the Schiff base, which, structurally, is a nitrogen analog of an aldehyde or ketone, in which the carbonyl group (C=O) is replaced by an imine group (C=N), a carbon-nitrogen double bond. Schiff base synthesis is a reversible reaction in which dialdehydes and aminobenzoic acids can be used as reactants. The efficacy of these reactions is controlled by two main factors that have a large impact on yield. The acid concentration shouldn't be to high ( pH between 4 and 5), slightly acidic conditions are required in which water loss occurs, opposite of that, if the solution is too acidic, the amine is protonated, which inhibits the first stage - the reaction cannot continue. Dialdehydes are organic compounds formed by intermolecular condensation reactions and polymerization reactions. They contain two aldehyde groups and in the reactions with aminobenzoic acids they form a double C=N bond with both groups. Dialdehydes can be synthesized form aldehydes and long-chain halogenalkanes under certain reactions conditions ( high temperature with ethanol as solvent). Aminobenzoic acids are organic compounds at which the amino group- is attached to the benzene ring of benzoic acid at three different sites. There are Three isomers of aminobenzoic acids, namely orto-aminobenzoic acid, meta-aminobenzoic acid and para-aminobenzoic acid. The use of acidic medium, deprotonates the nitrogen of the amino group of these isomers, and they reacts with the carbonyl group of the dialdehyde to form am inmino double C=N bond. IR spectroscopy provides us withs information on vibrational connections, which provest he presence of functional groups. Iti s based on the absorption of light by infrared radiation, which measures the amount of radiation absorbed by a compound as a function of wavelength. An infrared spectrometer based on the Fourire transform (FT-IR) is used by important information. The spectrum of Schiff bases shows vibrations of the C=N bond ( imino group) in the range 1680 - 1600 . The spectrum was comapred with the dialdehyde spectrum and aminobenzoic acids
Inner filter effect based optical sensors
No full textU binarnom sustavu optički aktivnih tvari, efekt unutarnjeg filtera uzrokovan je apsorbancijom emisijskog i/ili ekscitacijskog svijetla od strane absorbera. Efekt unutarnjeg filtera može se koristiti kaoefikasna analitička kvantitativna metoda. Moguće je određivanje totalnog antioksidativnog kapaciteta korištenjem utemeljeneCERAC metode (metoda gdje Ce(IV) selektivno oksidira antioksidativne komponente uzorka) pri ćemu se fluorometrijski prati promjena intenziteta fluorescentnog aditiva sa odgovarajućim ekscitacijskim spektrom i velikim Stock-ovim pomakom. Korištenjem fenomena efekta unutarnjeg filtera trebalo bi biti moguće razviti još pouzdaniju i precizniju metodu za određivanjetotalnog antioksidativnog kapacteta uzorka.In the binary system of optically active substances, the effect of the internal filter is caused by the absorption of emission and/or excitation light by the absorber. The internal filter effect can be used as an efficient analytical quantitative method. It is possible to determine the total antioxidant capacity using a grounded CERAC method (a method where Ce (IV) selectively oxidises the antioxidant components of the sample), fluorometrically monitoring the change in the intensity of the fluorescence additive emission with an appropriate excitation spectrum and a large Stock shift. Internal filter effect phenomenoncan be used to develop a more reliable and accurate method for determining the total antioxidant capacity of a sample
The influence of the electrode miniaturization on the characteristics of potentiometric sensor
No full textProvedena su potenciometrijska mjerenja korištenjem elektroda s različitim promjerom vodljive grafitne niti (6 mm, 500 μm i 30 μm) s dimetildioktadecilamonijevim tetrafenilboratom (DDA-TPB) kao senzorskim materijalom i o-nitrofeniloktileterom (o-NPOE) kao plastifikatorom. Istraživanje je provedeno kako bi se moglo utvrditi utječe li minijaturizacija elektrode na karakteristike potenciometrijskog senzora. Za uspostavljanje ravnoteže u membrani senzora korištena je potenciometrijska titracija, dok je za ispitivanje utjecaja minijaturizacije elektrode na odzivne karakteristike tenzidnog senzora korištena metoda direktne potenciometrije. Za potenciometrijske titracije kao analit je korišten natrijev dodecilsulfat (NaDDS, c = 4* mol/L), a kao titrant cetilpiridinijev klorid (CPC, c = 4* mol/L). Odziv senzora na NaDDS ispitan je u području od 2,5* mol/L do 5,0* mol/L, a mjerenja su provedena u ultra-čistoj vodi. Rezultati odzivnih karakteristika pokazali su sub-Nernstovski odziv od -52,2 ± 0,8 mV/dekadi aktiviteta za elektrodu standardne veličine s promjerom grafitnog štapića 6 mm (DDA-TPB_A). Minijaturizirana elektroda s promjerom gafitnog vlakna od 500 μm (DDA-TPB_B) pokazala je Nernstovski nagib od -59,5 ± 2,3 mV/dekadi aktiviteta, dok je najmanja elektroda s promjerom grafitnog vlakna od 30 μm (DDA-TPB_C) pokazala nagib od -14,2 ± 1,4 mV/dekadi aktiviteta i time se pokazala kao neprimjerena za određivanje anionskih tenzida pri niskim koncentracijama. Najnižu granicu detekcije, 1,3* mol/L, pokazala je DDA-TPB_A elektroda. Istraživanjem je utvrđeno da su elektrode s promjerom grafitne niti od 6 mm i 500 μm primjenjive za određivanje niskih koncentracija NaDDS te da nema značajne razlike u odzivnim karakteristikama minijaturiziranog potencijometrijskog senzora u odnosu na senzor standardne veličine. Treba ipak uzeti u obzir da je minijaturizaciju elektrode moguće provoditi do određene granice, pri kojoj elektroda još uvijek kvalitetno odrađuje svoju namjenu što je vidljivo iz primjera DDA-TPB_C elektrode koja je zbog izrazito tankog grafitnog vlakna promjera 30 μm, davala znatno lošije rezultate mjerenja.Potentiometric measurements using electrodes with different diameters of conductive graphite fiber (6 mm, 500 μm and 30 μm) with dimethyldioctadecylammonium tetraphenylborate (DDA-TPB) as the sensing material and o-nitrophenyl octyl ether (o-NPOE) as a plasticizer were performed. A study was carried out in order to determine whether the miniaturization of the electrode affects the potentiometric sensor characteristics. Potentiometric titration was used to balance the sensor membrane, while direct potentiometry was used to test the effect of electrode miniaturization on the response characteristics of the surfactant sensor. For potentiometric titrations, sodium dodecyl sulfate (NaDDS, c = 4* mol/L was used as the analyte, and cetylpyridinium chloride (CPC, c = 4* mol/L) as the titrant. Sensor response to NaDDS was tested in the range between 2,5* mol/L and 5,0* mol/L, and measurements were performed in ultra-pure water. Results of the response characteristics showed a sub-Nernst response of -52,2 ± 0,8 mV/decade of activity for a standard-sized electrode with a 6 mm graphite fiber diameter (DDA-TPB_A). A miniature electrode with a 500 μm graphite fiber diameter (DDA-TPB_B) showed a Nernst slope of -59,5 ± 2,3 mV/decade of activity, while the smallest electrode with a 30 μm graphite fiber diameter (DDA-TPB_C) showed a slope of -14,2 ± 1,4 mV/decade of activity and thus proved unsuitable for the determination of anionic surfactants at low concentrations. The lowest detection limit, 1,3* mol/L, was obtained using DDA-TPB_A electrode. The study found that electrodes with graphite fibers of 6 mm and 500 μm are applicable for the determination of low concentrations of NaDDS and that there is no significant difference in the response characteristics of a miniaturized potentiometric sensor relative to standard size sensors. However, it should be considered that the miniaturization of the electrode can be carried out to a certain limit, at which the electrode still performs its purpose in a good quality as can be seen from the example of the DDA-TPB_C electrode, which, due to the extremely thin graphite fiber with a diameter of 30 μm, gave significantly worse measurement results
Monitoring of platinum and rare earth elements in environment of eastern Croatia
No full textCilj ovog istraživanja bio je analizirati podatke o koncentracijama 18 elemenata: La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, Ru, Rh, Pd, Ir i Pt u okolišnim i biološkim uzorcima na području istočne Hrvatske. Nisu utvrđene statističke značajne razlike u koncentracijama analiziranih elemenata u urinu i serumu između stanovnika gradova i stanovnika manjih mjesta. Također, nije utvrđena povezanost između koncentracija 18 elemenata u uzorcima tla i maslačka (Taraxacum officinale). Najveće koncentracije Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Pd i Rh pronađene su u uzorcima maslačka prikupljenih s poljoprivrednih površina, dok su manje koncentracije pronađene u uzorcima maslačka prikupljenih uz prometnice. Pronađene su i statistički značajne razlike u koncentracijama između uzoraka maslačka s poljoprivrednih i uzoraka maslačka s nepoljoprivrednih područja, što ukazuje na potrebu daljnjeg praćenja u okviru ekološko-preventivnih aktivnosti.The aim of this study was to analyze data on concentrations of 18 elements: La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, Ru, Rh, Pd, Ir, and Pt in environmental and biological samples cellected in the territory of eastern Croatia. No statistically significant differences were found comparing the concentrations of the analyzed elements in urine and serum samples between urban and small-town residents. Also, correlation wasn't found between concentrations of 18 elements in soil and dandelion (Taraxacum officinale) samples. The highest concentrations of Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Pd, and Rh were found in dandelion samples collected from agricultural land, while smaller concentrations were found in dandelion samples collected along roads. There were also statistically significant differences in concentrations between dandelion samples from agricultural and non-agricultural areas, indicating the need for further monitoring in the context of environmental-preventive activities
Determination of anions and cations in the processed and unprocessed water samples by using spectrophotometry, ion chromatography and voltammetry
No full textRad je baziran na spektrofotometrijskoj analizi prerađene i neprerađene vode u trajanju od 5 tjedana. Spektrofotometrijskom analizom određivana je koncentracija mangana, željeza i amonijaka u vodi. Drugi dio rada bazira se na kromatografskoj analizi gdje su određivane koncentracije amonijevih (), nitratnih (), nitritnih () i sulfatnih () iona. Koncentracija ukupnog arsena ( i iona) određena je anodnom "stripping" voltametrijom dok je za određivanje arsenitnih iona () korištena diferencijalna pulsna voltametrija sa modificiranom elektrodom od staklastog ugljika. Cilj istraživanja bio je određivanje koncentracije navedenih kationa i aniona u prerađenoj i neprerađenoj vodi. Dobivene vrijednosti uspoređene su sa zakonskim regulativama. Uzimanje uzoraka vode koji su se koristili za ispitivanja mora se vršiti prema zakonom propisanim postupcima. Svrha redovitog praćenja odgovarajućih parametara je dobivanje osnovnih podataka o fizikalno-kemijskoj i mikrobiološkoj kvaliteti vode za ljudsku potrošnju te podataka o učinkovitosti rada postrojenja.Our study was based on spectrophotometric analysis of processed and unprocessed water in 5 weeks' time period. Spectrophotometric analysis was used to determine concentrations of manganese, iron and ammonia in water. The second part of our work is based on chromatographic analysis where concentrations of ammonium (), nitrate (), nitrite (), sulphate () ions were determined. Total arsenic concentration ( and ions) was detected with anodic stripping voltammetry, while. arsenite ions () concentration was obtained with differential pulse voltammetry by using modified glassy carbon electrode. The aim of this study was to determine the concentrations of the listed anions and cations in processed and unprocessed water samples. Obtained values were compared with legal regulations. Sampling of water for determination of its properties must be made according to the procedures regulated by law. The purpose of regular examination is obtaining basic information about physical, chemical and microbiological quality of the water for human use, and obtaining the data about efficiency of plant operation
Effect of system complexcity and vitamine C addition on calcium oxalate
No full textKalcijevi oksalati su kalcijeve soli oksalne kiseline i čine sastavni dio bubrežnih kamenaca. Kalcijev oksalat kritalizira u tri hidratna oblika: kalcijev oksalat monohidrat (COM, velevit), kalcijev oksalat dihidrat (COD, vedelit) i kalcijev oksalat trihidrat (COT, kaoksit). Urolitijaza je medicinski naziv za nastanak bubrežnih kamenaca u urinarnom traktu, a od nje oboljevaju podjednako muškarci i žene. Bez obzira što se većina kamenaca može liječiti bez operativnog zahvata provode se mnoga istraživanja kako bi se objasnio mehanizam, uzrok i moguća prevencija nastanka bubrežnih kamenaca. Ovim završnim radom ekperimentalno je pokazano da kompleksnost sustava i promjena mase dodanog vitamina C utječu na taloženje kalcijeva oksalata, posebno na morfologiju, veličinu i hidratnu fazu. Rezultati su obrađeni optičkom mikroskopijom, FTIR spektroskopijom i termogravimetrijskom analizom.Calcuim oxalates are calcium salts of oxalic acid and are the most common constituents of kidney stones. Calcuim oxalata crystallize in three most common forms: calciom oxalate monohydrate (COM, whewellite), calcium oxalate dihydrate (COD, weddelite) and calcium oxalate trihydrate (COT, caoxite). Urolithiasis is a medical term for formation of kidney stones in urinary tract and engages men and women equaly. Evendough many stones can be treated without surgical procedure, many researches are conducted in order to explain mechanism, cause and possible prevention of kidney stone formation. In this final thesis, it was proven experimentally that the change in vitamin C concentration affects morphology, size and hydrated phase of of calcium oxalates. The results were processed by optical microscopy, infrared (FT-IR) spectroscopy and thermal analysis (TGA)