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Mechanical recycling of the trimmer line : diploma thesis
No full textU ovom radu ispitan je utjecaj mehaničkog recikliranja na strukturu i toplinsku postojanost materijala od kojeg su izrađene niti za košnju. Niti za košnju su mehanički reciklirane u laboratorijskom dvopužnom ekstruderu. Infracrvena spektroskopija s Fourierovom transformacijom (FT-IR) upotrijebljena je za identifikaciju polimernog materijala od kojeg su izrađene niti te za određivanje strukture materijala nakon recikliranja. Usporedbom snimljenih FT-IR spektrograma s podatcima u literaturi i bazi podataka utvrđeno je da je poliamid 6 (poli( -kaprolaktam)) polimer od kojeg su izrađene niti za košnju. Također je utvrđeno da mehaničko recikliranje nije utjecalo na strukturu niti za košnju. Utjecaj mehaničkog recikliranja na toplinsku postojanost niti za košnju istraživan je primjenom termogravimetrijske analize (TG). Zaključeno je da mehaničko recikliranje neznatno poboljšava toplinsku postojanost materijala od kojeg su izrađene niti za košnju.In this paper, influence of mechanical recycling on the structure and thermal stability of the material from which the trimmer lines were made was examined. Trimmer lines were mechanically recycled in a laboratory twin screw extruder. Fourier transform infrared spectroscopy (FT-IR) was used to identify the polymer material from which the lines were made and to determine the structure of the material after recycling. By comparing the recorded FT-IR spectrograms with the data in the literature and the database, it was determined that polyamide 6 (poly( -caprolactam)) is the polymer from which the trimmer lines were made. It was also found that mechanical recycling did not affect the structure of the trimmer lines. The influence of mechanical recycling on the thermal stability of trimmer lines was investigated using thermogravimetric analysis (TG). It was concluded that mechanical recycling slightly improves the thermal stability of the material from which the trimmer lines were made
Wastewater treatment by hybrid electrocoagulation process with aluminium electrodes, zeolite and magnet : diploma thesis
No full textU ovom radu ispitano je djelovanje magneta na učinkovitost obrade otpadne kompostne vode s hibridinim procesom elektrokoagulacije s aluminijevim elektrodama uz dodatak sintetskog zeolita i primjene magneta. Eksperimenti su provedeni u trajanju od 10 do 30 minuta bez podešavanja početne pH vrijednosti, uz dvije brzine vrtnje miješala od 250 i 350 okr./min te prisutnost i odsutnost magneta. Učinkovitost procesa ispitivana je preko fizikalno-kemijskih pokazatelja, promjene mase elektroda te sposobnosti taloženja suspenzije. Na kraju je provedena analiza operativnih troškova na temelju Faradayeva zakona i stvarne potrošnje elektroda. Rezultati su pokazali da je nešto veći porast temperature otopine u eksperimentima s magnetom u trajanju od 20 i 30 minuta, porast pH vrijednosti za eksperimente u trajanju od 30 minuta, dok vrijednosti električne vodljivosti i prikupljene mase taloga osciliraju ovisno o vremenu kontakta, prisutnosti magneta i brzini vrtnje miješala. Prisutnost magneta je kod eksperimenata u trajanju od 30 minuta pridonijela većem smanjenju kemijske potrošnje kisika (KPK), a u eksperimentima u trajanju od 20 i 30 minuta za uklanjanje mutnoće. Međutim, elektrokoagulacija potpomognuta magnetom pokazuje trend veće potrošnje električne energije, dok je manja potrošnja elektroda uočena samo u eksperimentima pri 20 min vremena kontakta i brzini vrtnje od 250 okr./min.In this paper, the effect of magnets on the efficiency of waste compost water treatment with the hybrid process of electrocoagulation with aluminum electrodes with the addition of synthetic zeolite and magnets usage was examined. The experiments were carried out for 10 to 30 minutes without adjusting the initial pH value, with two mixing speeds of 250 and 350 rpm and the presence or absence of a magnet. The effectiveness of the process was examined through physico-chemical indicators, changes in the mass of the electrodes and the ability to settle the suspension. At the end, an analysis of operating costs was evaluated based on Faraday's law and the actual consumption of electrodes. The results showed that the increase in the temperature of the solution in the experiments with a magnet lasting 20 and 30 minutes was slightly higher, the increase in the pH value for the experiments lasting 30 minutes, while the values of the electrical conductivity and the collected mass of the precipitate fluctuated depending on the contact time, the presence of the magnet and mixing speed. The presence of the magnet contributed to a greater reduction of COD in the 30-minute experiments, and to the removal of turbidity in the 20- and 30-minute experiments. However, magnet-assisted electrocoagulation shows a trend of higher electricity consumption, while lower electrode consumption was observed only in experiments with 20 min of contact time and a rotation speed of 250 rpm
Isolation and analysis of multiply glycosylated desulfoglucosinolates from selected pland species of the Brassicaceae and Moringaceae families : diploma thesis
No full textU ovom radu analizirani su glukozinolati u biljnim vrstama Hesperis laciniata, Thlaspi perfoliatum (Brassicaceae) i Moringa oleifera (Moringaceae). Glavni cilj bio je izolacija i identifilacija desulfoglukozinolata iz različitih biljnih dijelova primjenom modificirane ISO 9167-1 metode te njihova kvalitativna i kvantitativna analiza korištenjem UHPLC-DAD-MS/MS sustava. Identificirano je ukupno 7 različitih desulfoglukozinolata, uključujući nekoliko do sada nepoznatih spojeva. Najveća koncentracija glukozinolata u H. laciniata utvrĎena je u cvijetu (110,08 µmol/g suhog biljnog materijala), dok je kod T. perfoliatum koncentracija bila najviša u komuščici (97,6 µmol/g). Kod sjemenki M. oleifera, dominantni spoj bio je glukomoringin (221,74 µmol/g). U biljci H. laciniata, najzastupljeniji glukozinolat bio je 4´- O-β-D-apiofuranozilglukomatronalin (69,57 µmol/g suhog biljnog materijala), dok je kod T. perfoliatum dominantni spoj bio 4´-O-(β-D-apiofuranoziloksi)benzil-glukozinolat (53,86 µmol/g). Nadalje, provedena je uspješna izolacija pojedinih glukozinolata korištenjem HPLC-DAD sustava sa sakupljačem frakcija. Iz biljke T. perfoliatum izolirane su tri frakcije: desulfoglukosinalbin, desulfo-apiofuranozilglukomatronalin i desulfo-(apiofuranoziloksi)benzil-glukozinolat. Rezultati ukazuju na specifične razlike u profilu glukozinolata meĎu vrstama, a identificirani spojevi predstavljaju značajan doprinos razumijevanju kemijske raznolikosti unutar porodica Brassicaceae i Moringaceae. Posebno se ističe identifikacija višestruko glikoziliranih glukozinolata, što doprinosi daljnjoj karakterizaciji bioloških i kemijskih svojstava ovih biljaka.In this study glucosinolates from the plant species Hesperis laciniata, Thlaspi perfoliatum (Brassicaceae), and Moringa oleifera (Moringaceae) were analyzed. The main goal was the isolation and identification of desulfoglucosinolates from different plant parts using a modified ISO 9167-1 method, followed by their qualitative and quantitative analysis using the UHPLC-DAD-MS/MS system. A total of seven different desulfoglucosinolates were identified, including several previously unknown compounds. The highest concentration of glucosinolates in H. laciniata was found in the flowers (110.08 µmol/g dry plant material), while in T. perfoliatum, the highest concentration was observed in the siliques (97.6 µmol/g). In the seeds of M. oleifera, the dominant compound was glucomoringin (221.74 µmol/g). In H. laciniata, the most abundant glucosinolate was 4´-O-β-D-apiofuranosylglucomatronalin (69.57 µmol/g dry plant material), whereas in T. perfoliatum, the dominant compound was 4´-O-(β-D- apiofuranosyloxy)benzyl-glucosinolate (53.86 µmol/g). Furthermore, successful isolation of individual glucosinolates was achieved using the HPLC-DAD system with a fraction collector. From T. perfoliatum, three fractions were isolated: desulfoglucosinalbin, desulfo-apiofuranosylglucomatronalin, and desulfo- (apiofuranosyloxy)benzyl-glucosinolate. The results highlight specific differences in glucosinolate profiles among the species studied, and the identified compounds represent a significant contribution to understanding the chemical diversity within the Brassicaceae and Moringaceae families. Notably, the identification of multiply glycosylated glucosinolates advances the characterization of the biological and chemical properties of these plants
Investigation of the corrosion behaviour of Ti and Ti6Al4V alloy in brackish water, seawater and seawater bittern : diploma thesis
No full textTi i Ti6Al4V legura imaju značajnu primjenu u medicini za izradu implantata, kao i za izradu dijelova konstrukcija kod koje se traže dobra mehanička svojstva, mala masa i visoka korozijska otpornost, što je bila i motivacija kod izbora materijala za istraživanje. U radu je provedeno ispitivanje korozijskog ponašanja Ti i Ti6Al4V legure u boćatoj, morskoj i gorkoj morskoj vodi. Elektrokemijska ispitivanja su obuhvaćala mjerenje potencijala otvorenog strujnog kruga (E OC ), kao i primjenu polarizacijskih metoda (linearne i potenciodinamičke polarizacije). Ti i Ti6Al4V legura pokazuju najpozitivniji potencijal u boćatoj vodi, a najnegativniji u gorkoj vodi. Najmanja vrijednost korozijske struje i najveća vrijednost polarizacijskog otpora dobiveni su mjerenjem u boćatoj vodi za Ti, dok je Ti6Al4V pokazala najmanju korozijsku otpornost u gorkoj vodi. Analiza površine elektroda nakon polarizacijskih mjerenja optičkom mirkoskopijom, optičkom profilometrijom i SEM/EDS ispitivanjima pokazala je mala oštećenja što ukazuje na visoku korozijsku otpornost Ti i Ti6Al4V legure u ispitivanim medijima.Ti and Ti6Al4V alloys have significant applications in medicine for the manufacture of implants, as well as for the manufacture of structural parts that require good mechanical properties, low weight and high corrosion resistance, which was the motivation for selecting these materials for research. In this work, the corrosion behavior of Ti and Ti6Al4V alloy in brackish, sea and bitter sea water was tested. Electrochemical investigations included the measurement of the open circuit potential (E OC ), as well as the application of polarization methods (linear and potentiodynamic polarization). Ti and Ti6Al4V alloy show the most positive potential in brackish water and the most negative in bitter water. The lowest value of corrosion current and the highest value of polarization resistance were obtained by measuring in brackish water for Ti, while Ti6Al4V showed the lowest corrosion resistance in bitter water. The analysis of the electrode surface after polarization measurements by optical microscopy, optical profilometry and SEM/EDS tests showed small damages, which indicates the high corrosion resistance of Ti and Ti6Al4V alloy in the tested media
Development and evaluation of the method from the determination of tiopronin in pharmaceutical preparations using the sequential injection technique with a spectrophotometric detector : diploma thesis
No full textPrimjenom slijedne analize injektiranjem uz spektrofotometrijski detektor razvijena je i vrednovana nova kinetička metoda za određivanje tiopronina (N-2-merkaptopropionil-glicin, MPG) u farmaceutskim pripravcima. Metoda se temelji na redoks-reakciji u kojoj tiopronin reducira žuti bis(batokuproindisulfonato)kuprat(II) kompleks u stabilan bis(batokuproindisulfonato)kuprat(I) kompleks, karakteristične žuto-narančaste boje, s apsorpcijskim maksimumom pri valnoj duljini od 483 nm. Apsorbancija formiranog kompleksa kontinuirano se mjerila pomoću UV-Vis spektrofotometra, pri čemu su se mjerenja izvodila u triplikatu. Univarijantnom metodom optimizirani su kemijski i protočni parametri sustava, na osnovu čega je konstruirana krivulja umjeravanja za određivanje linearnog dinamičkog područja metode. Regresijskom analizom dobivena je jednadžba pravca y = 5897x + 0,0176, s linearnim rasponom koncentracija analita od 8,0 × 10 -7 do 6,0 × 10 -5 mol L -1 . Određene su granica dokazivanja od 2,54 × 10 -7 mol L -1 i granica određivanja od 8,48 × 10 -7 mol L -1 . Metoda je vrednovana u pogledu točnosti, iskoristivosti i preciznosti, uključujući ponovljivost, učestalost i doseg reakcije. Točnost metode potvrđena je iskoristivošću između 100,70 i 110,81 %. Ponovljivost je bila zadovoljavajuća, uz relativno standardno odstupanje od 4,66 %. U jednom satu moguće je provesti 12 analiza u triplikatu, što daje ukupno 36 analiza. Reakcijski doseg je 90,50 %. Osim acetilsalicilne kiseline i visokih koncentracija borne kiseline, niti jedna od uobičajenih pomoćnih tvari u farmaceutskim proizvodima ne interferira. Razvijena metoda uspješno je primijenjena za određivanje tiopronina u farmaceutskom pripravku Captimer ® , a dobiveni rezultati pokazali su visoku korelaciju sa standardnom farmakopejskom metodom.Using sequential injection analysis with a spectrophotometric detector, a new kinetic method for the determination of tiopronin (N-2-mercaptopropionyl-glycine, MPG) in pharmaceutical preparations was developed and validated. The method is based on a redox reaction in which tiopronin reduces the yellow bis(bathocuproinedisulfonate)cuprate(II) to a stable bis(bathocuproinedisulfonate)cuprate(I), characterized by a yellow-orange color, with an absorption maximum at a wavelength of 483 nm. The absorbance of the formed complex was continuously measured using a UV-Vis spectrophotometer, with measurements performed in triplicate. The chemical and flow parameters of the system were optimized using the univariate method, based on which a calibration curve was constructed to determine the linear dynamic range of the method. Regression analysis yielded the equation y = 5897x + 0.0176, with a linear range of analyte concentrations from 8.0 × 10 -7 to 6.0 × 10 -5 mol L -1 . The limits of detection and quantification were determined as 2.54 × 10 -7 mol L -1 and 8.48 × 10 -7 mol L -1 , respectively. The method was evaluated in terms of accuracy, efficiency, and precision, including reproducibility, analysis frequency and reaction yield. The accuracy of the method was confirmed with efficiency ranging from 100.70% to 110.81%. The reproducibility was satisfactory, with a relative standard deviation of 4.66%. In one hour, 12 triplicate analyses can be performed, resulting in a total of 36 analyses. The reaction yield was 90.50%. Apart from acetylsalicylic acid and high concentrations of boric acid, none of the commonly present excipients in pharmaceutical products interfered with the method. The developed method was successfully applied for the determination of tiopronin in the pharmaceutical preparation Captimer®, and the obtained results showed a high correlation with the standard Pharmacopoeial method
Spectroscopic determination of glucosinolates in plants Sinapis alba and Lepidium draba : diploma thesis
No full textU ovom radu UHPLC-DAD-MS/MS analizom odreĎen je glukozinolatni profil različitih biljnih dijelova biljke Lepidium draba i nepoznatog biljnog uzorka te glukozinolatni profil sjemenki biljke Sinapis alba. Glukozinolati su iz uzoraka izolirani u desulfatiranome obliku modificiranom metodom ISO 9167-1. Dobiveni glukozinolatni profil biljke Lepidium draba usporeĎen je s glukozinolatnim profilom nepoznate biljne vrste kako bi se odredile kemotaksonomske značajke nepoznatog biljnog uzorka. U oba uzorka, najveći udio glukozinolata je pronaĎen u listu, a najmanji u stabljici. Pri tome, najzastupljeniji spoj u listu oba uzorka je glukorafanin (41,49 ± 4,05 μmol/g suhog biljnog materijala biljke Lepidium draba te 40,40 ± 3,62 μmol/g suhog biljnog materijala nepoznatog uzorka), a u cvatu pak glukosinalbin (32,03 ± 5,43 μmol/g u biljci Lepidium draba te 34,73 ± 0,76 μmol/g u nepoznatom uzorku). Najzastupljeniji glukozinolati u oba uzorka potječu od metionina. Na temelju znatne sličnosti glukozinolatnih profila uzoraka te UV i MS2 spektara, zaključeno je da nepoznatni uzorak vjerojatno pripada vrsti Lepidium draba. Obzirom da je glukozinolatni profil sjemenki biljke Sinapis alba bio uvelike jednostavniji od gore navedenih uzoraka, taj uzorak je posluţio za potvrdu strukture najzastupljenijeg spoja sjemenki - desulfoglukosinalbina. Struktura je potvrĎena NMR tehnikom te je utvrĎena β konfiguracija anomernog ugljikovog atoma glukozne jedinice glukosinalbina.In this paper, UHPLC-DAD-MS/MS analysis was used for determination of the glucosinolate profile of various plant parts of Lepidium draba and an unknown plant sample, as well as the glucosinolate profile of Sinapis alba seeds. Glucosinolates were isolated from the samples in their desulfated form using a modified ISO 9167-1 method. The obtained glucosinolate profile of Lepidium draba was compared with the glucosinolate profile of the unknown plant species in order to determine chemotaxonomic characteristics of the unknown plant sample. In both samples, the highest glucosinolate content was found in the leaves, while the lowest content was found in the stem. The most abundant compound in the leaves of both samples was glucoraphanin (41.49 ± 4.05 μmol/g dry plant material of Lepidium draba and 40.40 ± 3.62 μmol/g dry plant material of the unknown sample) and glucosinalbin in the inflorescence (32.03 ± 5.43 μmol/g in Lepidium draba and 34.73 ± 0.76 μmol/g in the unknown sample). The most abundant glucosinolates in both samples are derived from methionine. Based on the significant similarity in the glucosinolate profiles and UV and MS2 spectra of the samples, it was concluded that the unknown sample likely belongs to the Lepidium draba species. Since the glucosinolate profile of Sinapis alba seeds was much simpler than that of the above-mentioned samples, this sample was used for confirmation of the structure of the most abundant compound in the seeds - desulfoglucosinalbin. The structure was confirmed using NMR techniques, and the β configuration of the anomeric carbon atom of the glucose unit of glucosinalbin was determined
Chemical analysis of honey : diploma thesis
No full textU ovom diplomskom radu analizirane su fizikalno – kemijske karakteristike 33 uzorka meda i patvorine meda različitog botaničkog i geografskog podrijetla. Određena je njihova kiselost, električna vodljivost, sadržaj pepela i vode te koncentracija minerala i teških metala. Primjenom tehnike masene spektrometrije s induktivno spregnutom plazmom (ICP-MS) određeni su glavni elementi (Ca, K, Mg, Na, P i S) te elementi i ultra-elementi u tragovima (Ag, Al, As, B, Ba, Be, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Si, Sn, Sr, Ti, Tl i Zn). Iz dobivenih rezultata i njihovom usporedbom s važećom zakonskom regulativom izmjerena vrijednost električne vodljivosti kod jednog uzorka je viša, a kod dva uzorka niža od vrijednosti električne vodljivosti propisane Pravilnikom o medu. Kod rezultata sadržaja vode u medu jedan uzorak nije u skladu s Pravilnikom o medu. Izmjerene koncentracije teških metala kod devet uzoraka ne zadovoljavaju zakonsku regulativu, odnosno izmjerene koncentracije prelaze najviše dopuštene količine (NDK) prema Pravilniku o toksinima, metalima, metaloidima, te drugim štetnim tvarima koje se mogu nalaziti u hrani. Jedan uzorak cvjetnog meda pokazao je najviše razine većine minerala i teških metala u usporedbi s drugim uzorcima. Ova analiza ključna je za osiguranje kvalitete i sigurnosti meda, naglašavajući potrebu za strogim nadzorom i poštivanjem propisa o sigurnosti hrane.In this diploma thesis, the physico-chemical properties of 33 honey samples, including adulterated honey, from different botanical and geographical areas of origin were analyzed. Acidity, electrical conductivity, ash, water content and concentration of minerals and heavy metals were determined. The concentrations of major elements (Ca, K, Mg, Na, P and S), trace elements and ultraelements (Ag, Al, As, B, Ba, Be, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Si, Sn, Sr, Ti, Tl and Zn) were determined using the inductively coupled plasma mass spectrometry (ICP-MS) technique. The results showed that three samples did not meet the standards for electrical conductivity and one sample did not meet the legal requirements for the water content of honey. The heavy metal concentrations in nine samples did not meet the legal standards. In particular, one sample of blossom honey had the highest levels of most minerals and heavy metals compared to the other samples. This analysis is crucial for ensuring the quality and safety of honey and underlines the need for strict monitoring and compliance with food safety regulations
Determination of glucosinolates in Biscutella laevigata and Eruca vesicaria and their isolation using accelerated solvent extraction : diploma thesis
No full textU ovom radu određen je glukozinolatni profil sjemena rokule (Eruca vesicaria) i odabranih biljnih dijelova biokovske i poljske glatke dvoštitke (Biscutella laevigata) izravnom UHPLC-DAD-MS/MS analizom preko odgovarajućih desulfoglukozinolata. Ekstrakcija glukozinolata provedena je sukladno modificiranoj ISO 9167-1 metodi. Dodatno, glukozinolati sjemena rokule izolirani su metodom ubrzane ekstrakcije otapalom pri povišenom tlaku (ASE) s ciljem kvalitativne i kvantitativne usporedbe dobivenih glukozinolata s ISO metodom. Ispitana je ekstrakcijska učinkovitost ASE na temperaturama od 50 ºC, 70 ºC i 90 ºC i s ulaznim količinama biljnog materijala od 1 g i 100 mg. Analizom sjemena rokule, neovisno o primijenjenoj metodi izolacije, dokazana je prisutnost glukoerucina u najvišim koncentracijama (6,13-90,24 μmol/g suhog biljnog materijala). U dosta nižem sadržaju pronađeni su glukorafanin (0,14-1,46 μmol/g) i glukosinalbin (0,13-0,65 μmol/g), a ostali glukozinolati su prisutni u tragovima. Pojedinačni i ukupni (92,35 μmol/g) sadržaji glukozinolata pokazali su se značajno višim primjenom ISO 9167-1 metode. Najveći sadržaj glukozinolata za ASE dobiven je pri temperaturi 70 ºC, tj. 32,57 μmol/g za 1 g i 7,80 μmol/g za 100 mg. Glukohirsutin i glukobrasicin su pronađeni u svim biljnim dijelovima biokovske glatke dvoštitke, a najveći sadržaj bio je u komuški (43,57 μmol/g za glukohirsutin i 14,08 μmol/g za glukobrasicin). Općenito, komuška se pokazala najbogatijom glukozinolatima (57,85 μmol/g), a najsiromašnija je bila stabljika (6,49 μmol/g). Analizom poljske glatke dvoštitke, glukozinolati su ustanovljeni samo u sjemenu unutar kojeg je najsadržajniji bio glukohirsutin (30,51 μmol/g), dok uzorak dobiven in vitro nije sadržavao glukozinolate.In this paper, the glucosinolate profile of rocket seeds (Eruca vesicaria) and selected plant parts of Biokovo and Polish buckler mustard (Biscutella laevigata) was determined using UHPLC-DAD-MS/MS analysis by their desulfo-counterparts. Glucosinolate extraction was performed according to the modified ISO 9167-1 method. Additionally, the glucosinolates of rocket seeds were isolated by accelerated solvent extraction at elevated pressure (ASE) with the aim of comparing the qualitative and quantitative glucosinolate profile with the ISO method. The extraction efficiency of ASE was tested at temperatures of 50 ºC, 70 ºC and 90 ºC with the amounts of plant material of 1 g and 100 mg. The analysis of rocket seeds, regardless of the applied isolation method, revealed the presence of glucoerucin having the highest content (6.13-90.24 μmol/g of dried plant material). Glucoraphanin (0.14- 1.46 μmol/g) and glucosinalbin (0.13-0.65 μmol/g) were found in much lower concentrations, and other glucosinolates were present in traces. Individual and total (92.35 μmol/g) glucosinolate contents were shown to be significantly higher using the ISO 9167-1 method. The highest yield for ASE was obtained at 70 ºC with total glucosinolate content of 32.57 μmol/g for 1 g and 7.80 μmol/g for 100 mg. Glucohirsutin and glucobrassicin were found in all plant parts of buckler mustard from Biokovo and the highest contents were found in siliquae (43.57 μmol/g for glucohirsutin and 14.08 μmol/g for glucobrassicin). In general, siliquae proved to be the richest in glucosinolates (57.85 μmol/g), while the stem had the lowest (6.49 μmol/g). By analyzing the Polish buckler mustard, glucosinolates were found only in the seeds, the most abundant of which was glucohirsutin (30.51 μmol/g), while the glucosinolates were absent in the plant sample obtained in vitro
Volatile compounds of wine vinegar flavored with shallots : diploma thesis
No full textVinski ocat je proizvod koji je poznat od davnina, a koristi se kao dodatak prehrani i konzervans. Nastaje dvostrukom fermentacijom. Prva je alkoholna kojom se dobije vino, zatim octena fermentacija koja se odvija uz pomoć octenih bakterija. Osim od vina, odnosno grožđa, ocat se može napraviti od bilo koje sirovine bogatom šećerima. Ocat je proizvod koji ima potencijal predstavljanja na tržištu kao proizvod s dodanom vrijednošću na način da mu se obogati kemijski sastav dodavanjem različitih vrsta voća ili povrća. Ljutika je zanemarena poljoprivredna kultura koja raste najčešće u priobalnom području Hrvatske. U Hrvatskoj postoje tri genotipa ljutike Allium cepa var. aggregatum, Allium x proliferum i Allium x cornutum. Ljutika je bogata fenolnim spojevima što je čini odličnim antioksidansom. Osim fenola, ima velik broj sumporovih spojeva, aminokiselina, vitamina i minerala. U ovom radu se provodila maceracija crvenog vinskog octa korištenjem dvije vrste ljutike; domaća ljutika s područja Omiša (vjerojatni genotip A. x cornutum) te ljutika kupljena u maloprodaji (vjerojatni genotip A. cepa var. aggregatum). Lukovice ljutike su macerirane u octu u različitim udjelima (10, 20, 30 i 40%) tijekom 9 mjeseci, a svaka 3 mjeseca su uzimani uzorci za analizu hlapljivih spojeva. U pripremljenim aromatiziranim octevima ekstrakcija hlapljivih spojeva provedena je metodom mikroekstrakcije vršnih para na krutoj fazi (HS-SPME), a analiza izoliranih spojeva korištenjem tehnike plinske kromatografije- spektrometrije masa (GC-MS). Dobiveni rezultati ovog eksperimenta su pokazali da se u vinskom octu nalazi 21 hlapljivi spoj, u domaćoj ljutici 15 i kupovnoj 13 spojeva. U octu najviše ima octene kiseline i estera. U ljutici prevladavaju sumporovi hlapljivi spojevi koji su tipični za rod Allium. Nakon maceracije lukovica u octu, ocat mijenja svoj sastav u kojem se smanjuje udio octene kiseline i povećava udio sumporovih spojeva tipičnih za ljutiku. Ocat mijenja svoj senzorski opis na sumporasto, luk i poriluk. Dužom maceracijom i većim udjelom lukovica u octu veći je udio sumporovih spojeva.Wine vinegar is a product that has been known since ancient times, and is used as a food supplement and preservative. It is produced by double fermentation. The first is alcoholic fermentation, which produces wine, followed by acetic fermentation, with help of acidic bacteria. Apart from wine or grapes, vinegar can be made from any raw material rich in sugars. Vinegar is a product that has the potential to be presented on the market as a product with added value by enriching its chemical composition by adding different types of fruits or vegetables. Shallot is a neglected agricultural crop that grows mostly in the coastal area of Croatia. In Croatia, there are three shallot genotypes Allium cepa var aggregatum, Allium x proliferum and Allium x cornutum. Shallot is rich in phenolic compounds, which makes it an excellent antioxidant. In addition to phenols, it has a large number of sulfur compounds, amino acids, vitamins and minerals. In this thesis, maceration of red wine vinegar was carried out using two types of shallots; domestic shallots from Omiš area (probable genotype A. x cornutum) and shallots bought in retail (probable genotype A. cepa var. aggregatum). Shallot bulbs were macerated in vinegar in different proportions (10, 20, 30 and 40%) for 9 months, and samples were taken every 3 months for the analysis of volatile compounds. In the prepared aromatized vinegars, the extraction of volatile compounds was carried out using the method ofheadspace solid-phase microextraction (HS-SPME) and the analysis of the isolated compounds using the technique of gas chromatography-mass spectrometry (GC-MS). The results of this experiment showed that there are 21 volatile compounds in wine vinegar, 15 compounds in domestic shallots and 13 compounds in purchased shallots. Vinegar contains mostly acetic acid and esters. Volatile sulfur compounds that are typical of the genus Allium predominate in shallots. After the bulbs are macerated in vinegar, the vinegar changes its composition, in which the proportion of acetic acid decreases and the proportion of sulfur compounds typical of shallots increases. Vinegar changes its sensory description to sulphurous, onion and leek. Longer maceration and a higher proportion of bulbs in vinegar results in a higher proportion of sulfur compounds
Crystal violet dye removal from aqueous solution by electrocoagulation : bachelor thesis
No full textUklanjanje boje Crystal Violet (CV) iz vodene otopine (4 ± 0.23 mg/L CV + 2 mg/L NaCl) procesom elektrokoagulacije (EK) provedeno je u dva smjera. U prvom slučaju promatran je utjecaj gustoće struje (0.016, 0.024 i 0.032 A/cm 2 ; pH = 3.2), dok je u drugom slučaju razmatran utjecaj početne pH vrijednosti (3.2, 5.5 i 7.0; i = 0.024 A/cm 2 ) na uklanjanje CV boje. Tijekom EK procesa, koji je trajao 50 minuta, promatrana je promjena pH, temperature, električne provodnosti te koncentracije CV boje. Učinkovitost uklanjanja CV boje EK procesom je izuzetno dobra. Pri tome, uklanjanje boje raste s vremenom trajanja procesa te porastom gustoće struje i porastom pH vrijednosti. Izuzetno dobri rezultati postignuti su primjenom najveće gustoće struje (potpuno uklanjanje nakon 40 min) te u slučaju početne pH vrijednosti od 5.5 (potpuno uklanjanje nakon 30 min). Tijekom EK procesa dolazi do potrošnje anodnog, ali i katodnog materijala. Potrošnja elektrodnih materijala se povećava s porastom gustoće struje i pH vrijednosti otopine pri čemu je utjecaj gustoće struje izraženiji. Izgled površina elektroda (snimljenih svjetlosnim mikroskopom) ukazuje na činjenicu da se anode tijekom EK procesa otapaju ravnomjerno i lokalno, dok katode uglavnom podliježu ravnomjernoj koroziji.The removal of the dye Crystal Violet (CV) from a aqueous solution (4 ± 0.23 mg/L CV + 2 mg/L NaCl) by the process of electrocoagulation (EC) was performed in two directions. In the first case, the influence of current density (0.016, 0.024, and 0.032 A/cm 2 ; pH = 3.2) was observed, whereas in the second case, the influence of initial pH (3.2, 5.5, and 7.0; i = 0.024 A/cm 2 ) on the removal of CV dye was considered. During the EC process, which lasted 50 minutes, changes in pH, temperature, electrical conductivity, and CV dye concentration were observed. The efficiency of CV dye removal by the EC process is extremely good. At the same time, the dye removal increases with the duration of the process and with the increase of the current density and pH of the solution. Extremely good results were obtained at the highest current density (complete removal after 40 min) and at an initial pH of 5.5 (complete removal after 30 min). During the EC process, anodic and cathodic material is consumed. The consumption of electrode material increases with the increase of current density and pH of the solution, with the influence of current density being more pronounced. The appearance of the electrode surfaces (taken with an light microscope) shows that the anodes dissolve uniformly and locally during the EC process, while the cathodes are mostly subject to uniform corrosion