Repository of the Faculty of Chemistry and Technology, University of Split
Not a member yet
1086 research outputs found
Sort by
Spectrophotometric determination of total phenolics in seaweeds : bachelor thesis
No full textAlge su važan izvor različitih bioaktivnih spojeva, stoga su od iznimne važnosti otkrića i razvoj novih analitičkih metoda i tehnika za proučavanje njihovih metabolita. Osobitu pozornost znanstvenika privukli su fenoli smeđih algi koji su karakteristični samo za te organizme, a nazivaju se florotanini. Cilj ovog završnog rada je bio postaviti metodu određivanja ukupnih fenola na dva uređaja; klasičnom UV-VIS spektrofotometru i mikrotitarskom čitaču ploča. Kod postavljanja metode korištene su dvije otopine standarda, galna kiselina i floroglucinol. Galna kiselina je općenito najkorišteniji standard za izradu baždarnih pravaca i izražavanje rezultata određivanja fenola u različitim uzorcima (biljke, plodovi, sokovi, prerađevine, itd.), dok je floroglucinol osnovna građevna jedinica florotanina. Obzirom da se rezultati određivanja sadržaja fenola u algama u znanstvenim studijama izražavaju preko oba spoja, postavljanje metode određivanja ukupnih fenola korištenjem oba standarda može olakšati njihovu međusobnu usporedbu.Seaweeds are an important source of various bioactive compounds, so discovery and development of new analytical methods and techniques for the study of their metabolites are extremely important. Special attention has been drawn to the brown algae phenolics, which are unique to these organisms and are called phlorotanins. The aim of this bachelor thesis was to set up a method for the determination of total phenolics using two devices; classic UV-VIS spectrophotometer and microtiter plate reader. Two standard solutions, gallic acid and phloroglucinol, were used in setting up the method. Gallic acid is generally the most widely used standard for creation of calibration curves and determination of phenols in various samples (plants, fruits, juices, processed products, etc.), while phloroglucinol is the basic building unit of phlorotanins. Since in the scientific literature the phenolic content of seaweed samples is expressed using both standards, setting up a method for determining total phenols using both standards can provide easier comparison of the results
Synthesis and morphological analysis of a potential mesoporous metamaterial : bachelor thesis
No full textPodručje metamaterijala obrađeno je klasifikacijom i opisom, koji je opširniji za najzastupljenije primjere. Također su prikazane osnovne teorijske činjenice, koje objašnjavaju pojave u njima. Dan je poseban osvrt na porozne metamaterijale, koji su često i nanostrukturirani. Mogućnost preparacije i karakterizacije takvih materijala ilustrirana je na primjeru odabranog filma cinkovog oksida, u eksperimentalnom dijelu rada. Obrađen je uzorak mezoporoznog ZnO filma dobiven,depozicijom na posebno prepariranim podlogama, putem hidrotermalne sinteze uz SDS surfaktant. SEM i GIXD analiza uzoraka pokazala je da je film uniforman, s površinom koja ukazuje na poroznost i s jako izraženom kristalografskom teksturom. GISAXS metodom analize određeno je da objekti raspršenja čine uređen sustav mezopora te je procijenjena udaljenost između njih. Predložen je model kojim se može predstaviti ovakva mezoporozna morfologija filmova, koja ih klasificira kao potencijalne metamaterijale ili njihove komponente.The area of the metamaterials is presented by classification and description, which is more extensive for the most commonly used examples. Basic theoretical facts are also given, which explain their specific phenomena. Particular attention is paid to porous metal materials, which are often nanostructured. The ability to prepare and characterize such materials is illustrated by the example of a selected zinc oxide film, in the experimental part of the work. Sample of microporous ZnO film was obtained by deposition on the specially prepared substrate, via hydrothermal synthesis with the SDS surfactant. SEM and GIXD sample analyzes have shown that the film is uniform, with a surface that indicates porosity and with a very pronounced crystallographic texture. The GISAXS analysis method determined that the scattering objects make a well- ordered mesoporous system. Periodic distance between pores was estimated. A model has been proposed to present such mesoporous morphology of films, which classifies them as potential metamaterials, or their components
Green synthesis of colloidal silver with chemical deposition by different natural reducens : diploma thesis
No full textU ovom radu provedena je sinteza koloidnog srebra uz trinatrijev citrat dihidrat i askorbinsku kiselinu kao odgovarajuće reducense. Na osnovu dobivenih UV-Vis pikova, procijenjena je veličina koloidnih čestica te se zaključilo koji uvjeti su najpogodniji za sintezu uz odgovarajuće redukcijsko sredstvo. Pripremljene su standardne otopine 0,001 M AgNO 3 i 0,002 M NaBH 4 , te otopine srebrovog nitrata i trinatrijevog citrata dihidrata u koncentracijama 0,010 M, 0,016 M, 0,004 M. Sinteza je provedena pri 95 °C uz miješanje. Pripremljene su i otopine srebrovog nitrata i askorbinske kiseline, u koncentracijama 0,010 M, 0,020 M, 0,040 M, te je provedena sinteza pri sobnoj temperaturi, uz miješanje, i pri 50 °C. Kvaliteta koloidnog srebra ocjenjuje se na osnovi intenziteta Tyndallovog efekta, a apsorbancija dobivenih koloida određuje se UV-Vis spektrofotometrom. Rezultati ispitivanja potvrdili su uspješno korištenje trinatrijevog citrata dihidrata i askorbinske kiseline kao reducense za sintezu koloidnog srebra. Koloidnom srebru sintetiziranom pomoću natrijevog borohidrida procijenjena veličina čestica bila je oko 14 nm, dok je koloidnom srebru sintetiziranom pomoću askorbinske kiseline odgovarala veličina čestica od 14 do 35 nm. Na osnovi intenziteta Tyndallovog efekta pokazalo se da su dobiveni bolji rezultati sinteze uz grijanje pri 50 °C za askorbinsku kiselinu, dok se kod sinteze s trinatrijevim citratom dihidratom dobila mala količina koloidnog srebra jer sinteza nije bila do kraja završena.In this study, the synthesis of colloidal silver with trisodium citrate dihydrate and ascorbic acid was performed as appropriate reducing agents. Based on the obtained UV-Vis peaks, the size of the colloidal particles was estimated and it was concluded which conditions were most suitable for synthesis with the appropriate reducing agent Standard solutions of 0.001 M AgNO 3 and 0.002 M NaBH 4 were prepared, as well as solutions of silver nitrate and trisodium citrate dihydrate solutions at concentrations of 0,010 M, 0,016 M, 0,004 M. The synthesis was carried at 95 °C, with stirring. Silver nitrate and ascorbic acid solutions were prepared at concentrations of 0,010 M, 0,020 M, 0,040 M, and synthesis was carried out at room temperature, with stirring, and at 50 °C. The quality of colloidal silver is evaluated based on the intensity of the Tyndall effect, and the absorbance of the colloids obtained is determined by a UV - Vis spectrophotometer. The test results confirmed the successful use of trisodium citrate dihydrate and ascorbic acid as reducing agents for the synthesis of colloidal silver. The colloidal silver synthesized by sodium borohydride had an estimated particle size of about 14 nm, while the colloidal silver synthesized using ascorbic acid corresponded to a particle size of 14 to 35 nm. On the basis of the intensity of the Tyndall effect, it was shown that better synthesis results were obtained with heating at 50 °C for ascorbic acid, while the synthesis with trisodium citrate dihydrate produced a small amount of colloidal silver because the synthesis was not completely complete.
Synthesis of transparent toilet soap from vegetable oils : bachelor thesis
No full textSapuni su kemijski spojevi nastali bazičnom hidrolizom masti i ulja tj. procesom saponifikacije, a upotrebljavaju se još od davnina kao sredstva za pranje, za osobnu higijenu ili u kućanstvu. Proces dobivanja sapuna ostao je praktički nepromijenjen godinama, međutim u posljednje vrijeme je došlo do povećane potražnje ljudi za higijenskim i kozmetičkim preparatima na bazi prirodnih sirovina što je potaknuto povećanjem svijesti o utjecaju sintetskih materijala na zdravlje i okoliš. Cilj ovog završnog rada bio je sintetizirati proziran sapun od različitih vrsta biljnih ulja te ispitati utjecaj dodanih komponenata, količine alkohola i vrste šećera na prozirnost sapuna. Sapuni su pripravljeni postupkom na toplo. Korišteno je palmino, kokosovo i ricinusovo ulje te etanol, glicerol i saharoza (u prahu i kristal). Dobiveni sapuni su analizirani i njihova je moć pjenjenja uspoređena s moći pjenjenja komercijalno dostupnog sapuna. Dobiveni sapuni su po definiciji prozirni sapuni.Soaps are fatty acid salts obtained by the process of saponification or alkaline hydrolysis of fats and oils and have been used since ancient times as a detergents, for personal hygiene or in the household. The process of making soap has remained practically unchanged for many years but lately there has been increased demand from people for hygienic and cosmetic preparations based on natural materials. It is a result of increasing awareness of the impact of synthetic materials on health and the environment. The aim of this final work was to synthesize transparent soap from different types of vegetable oils, and to examine the influence of added components, the amount of alcohol and the type of sugar on the transparency of the soap. The soaps were prepared by the hot process; using palm, coconut and castor oil, glycerol, ethanol and sucrose (powder and crystal). The obtained soaps were analyzed and their foaming power was compared with the foaming power of commercially available soap. The resulting soaps are transparent soaps by definition
Determination of cadmium concentration in plants of Lepidium sativum L. grown on enriched soil, using atomic absorption spectroscopy : bachelor thesis
No full textBiljka Lepidium sativum L. je jednogodišnja kultura koja potječe iz jugozapadne Azije. U sebi sadrži mnoge ljekovite tvari, međutim u ljudskoj prehrani je slabo korištena. Tijekom godina sve se više ispituje njena mogućnost hiperakumulacije teških metala. Teški metali se mogu odrediti pomoću atomske apsorpcijske spektroskopije, analitičke tehnike koja se koristi za kvantitativno i kvalitativno određivanje elementa. Zeoliti su alumosilikatni minerali koji se koriste kao katalizatori i adsorbensi. Oni su bogaćeni kadmijem u rasponu koncentracija od 2 mM do 16 mM te su potom miješani sa zemljom u kojoj je uzgajana biljka Lepidium sativum L. U ovom radu opisan je uzgoj biljke Lepidium sativum L. na bogaćenom tlu te je opisana priprema biljnog materijala za analizu atomskom apsorpcijskom spektroskopijom. Na temelju dobivenih rezultata izvedeni su zaključci o mogućoj hiperakumulaciji.The Lepidium sativum L. plant is an annual crop native to southwest Asia. It contains many medicinal substances, but it is poorly distributed in the human diet. Over the years, the possibility of this plant hyperaccumulating heavy metals has been increasingly explored. Heavy metals can be determined by atomic absorption spectroscopy, an analytical tehnicque used for the quantitative and qualitative determination of an element. Zeolites are alumosilicate minerals used as catalysts and adsorbents. They are enriched in cadmium in the concentration range of 2 – 16 mM and then mixed with the soil in which the plant Lepidium sativum L. was grown. This paper describes the cultivation of the plant Lepidium sativum L. on enriched soil and describes the preparation of plant material for analysis by atomic absorption spectroscopy. On the basis of the obtained results, conclusions were drawn about possible hyperaccumulation
Investigation of corrosion behavior of CuAlMn alloy in chloride and sulfate electrolytes : diploma thesis
No full textU radu je provedeno ispitivanje elektrokemijskog ponašanja CuAlMn legure u 0.5 mol dm -3 NaCl otopini bez i u prisustvu 0.1, 0.3 i 0.5 mol dm -3 Na 2 SO 4 pri T = 20 o C i pH = 7. Primijenjene su elektrokemijske tehnike kao što su mjerenje potencijala otvorenog strujnog kruga, metode linearne i potenciodinamičke polarizacije. Rezultati ispitivanja su pokazali da prisustvo sulfata u otopini klorida dovodi do smanjenja gustoće korozijske struje i do povećanja vrijednosti polarizacijskog otpora. Kod viših anodnih potencijala, dobivene su veće anodne gustoće struje kod mjerenja u prisustvu sulfatnih iona zbog veće topljivosti bakrova sulfata, koji nastaje na površini elektroda. Utjecaj vremena izlaganja legure elektrolitu 0.5 mol dm -3 NaCl i 0.5 mol dm -3 NaCl + 0.5 mol dm -3 Na 2 SO 4 ispitan je mjerenjem metodom linearne polarizacije u vremenskom periodu od 24 sata, pri čemu su vrijednosti polarizacijskog otpora rasle s vremenom i u NaCl i u NaCl+Na 2 SO 4 otopini, s time što su u otopini sa sulfatnim ionima ove vrijednosti bile značajno više. Nakon elektrokemijskih mjerenja, korodirane površine elektroda ispitane su optičkim i elektronskim mikroskopom.The electrochemical behavior of CuAlMn alloy in 0.5 mol dm -3 NaCl solution without and in the presence of 0.1, 0.3 and 0.5 mol dm -3 Na 2 SO 4 at T = 20 o C and pH = 7 was investigated. Conventional electrochemical techniques including open circuit potential measurements, linear and potentiodynamic polarization method were used. After electrochemical measurements, the corroded electrode surfaces were examined with an optical and electron microscope. The results showed that the presence of sulfate in the chloride solution leads to a decrease in corrosion current density values and to an increase in polarization resistance values. At higher anode potentials, higher anodic current densities were obtained in the presence of sulfate ions, due to the higher solubility of copper sulfate, which is formed on the electrode surface. The effect of electrolyte exposure time on 0.5 mol dm -3 NaCl and 0.5 mol dm -3 NaCl + 0.5 mol dm -3 Na 2 SO 4 was examined by measuring with linear polarization method over a period of 24 hours, with the polarization resistance values increasing with time in both NaCl and NaCl + Na 2 SO 4 solution, and these values being significantly higher in the solution with sulfate ions. After electrochemical measurements, the corroded electrode surfaces were examined with an optical and electron microscope
Synthesis and characterization of poly(vynil-alcohol) by the alcoholysis of poly(vinil-acetate) : bachelor thesis
No full textU ovom radu sintetiziran je poli(vinil-alkohol) (PVAL) alkoholizom poli(vinil-acetata) (PVAC) te je napravljena karakterizacija sintetiziranog i izvornog (kupljenog) PVAL-a pomoću infracrvene spektroskopije s Fourierovom tranformacijom (FT-IR) koja je primijenjena za potvrdu strukture polimera, odnosno uspješnosti sinteze PVAL-a alkoholizom poli(vinil-acetata), zatim diferencijalnom pretražnom kalorimetrijom (DSC) koja daje uvid u toplinska svojstva PVAL-a i termogravimetrijskom analizom (TG) s kojom se dobije uvid u toplinsku razgradnju PVAL-a. Usporedbom FT-IR spektrograma izvornog i sintetiziranog PVAL-a dobiven je koeficijent korelacije 89,5%. Te vrijednosti nisu dovoljno velike da bi potvrdile da se zaista radi o PVAL-u, međutim, prikazuju karakteristične vibracijske vrpce za čisti PVAL s blagim odstupanjem čime se dokazuje da je PVAL uspješno sintetiziran. DSC normaliziranim krivuljama potvrđeni su zaključci dobiveni FT-IR-om, ali temeljem vrijednosti staklišta, kristališta i tališta. Preklapanjem DTG krivulja dolazi se do istog zaključka, bliski rezultati u razgradnim stupnjevima potvrđuju da je sinteza PVAL-a alkoholizom PVAC-a uspješno provedena.In this paper poly(vinyl alcohol) (PVAL) was synthesized by the alcoholysis of poly(vynil acetate) (PVAC) and characterization of synthesized and original (purchased) PVAL was preformed using infrared spectroscopy with Fourier transform (FT-IR) which was applied to confirm the structure of the polymer or the success of the synthesis PVAL by the alcoholysis of PVAC, followed by differential scanning calorimetry (DSC) which gave an insight into the thermal properties of PVAL and thermogravimetric analysis which gives an insight into thermal decomposition of PVAL. By comparing FT-IR spectrograms of original and synthesized PVAL, correlation coefficient 89,5% was obtained. These values are not large enough to confirm that it is indeed PVAL however they show the characteristic vibration bands for pure PVAL with a slight deviation thus proving that PVAL has been succesffully synthesized. DSC normalized curves confirm the conclusions obtained by FT-IR but based on the glass, crystal and melting point. By overlapping the DTG curves the same conclusion was reached, close results in the degradation steps confirm that the synthesis of PVAL by the alcoholysis of PVAC was successfully implemented
Synthesis and characterization of poly(vinil acetate) prepared by the emulsion polymerization : bachelor thesis
No full textU ovom radu sintetiziran je poli(vinil-acetat) (PVAC) emulzijskom polimerizacijom vinil-acetata napravljena je karakterizacija sintetiziranog i izvornog (kupljenog) PVAC-a pomoću infracrvene spektroskopije s Fourierovom tranformacijom (FT-IR) koja je primijenjena za potvrdu strukture polimera, odnosno uspješnosti sinteze PVAC-a emulzijskom polimerizacijom vinil-acetata, zatim diferencijalnom pretraţnom kalorimetrijom (DSC) koja je dala uvid u toplinska svojstva PVAC-a i termogravimetrijskom analizom (TG) koja je dala uvid u toplinsku razgradnju PVAC-a. Usporedbom FT-IR spektrograma izvornog i sintetiziranog PVAC-a dobiven je koeficijent korelacije 87,7% te vrijednost nije dovoljno velika da bi potvrdila da se zaista radi o PVAC-u, meĊutim karakteristiĉne vibracijske vrpce za ĉisti PVAC s blagim odstupanjem ĉime se dokazuje da je PVAC uspješno sintetiziran. DSC normaliziranim krivuljama potvrĊuju se zakljuĉci dobiveni FT-IR-om, ali temeljem vrijednosti staklišta. Preklapanjem DTG krivulja dolazi se do istog zakljuĉka, bliski rezultati u razgradnim stupnjevima potvrĊuju da je sinteza PVAC-a emulzijskom polimerizacijom vinil-acetata uspješno provedena.In this thesis, poly(vinyl acetate) (PVAC) was synthesized by emulsion polymerization of vinyl- acetate and the characterization of synthesized and original (purchased) PVAC was performed using infrared spectroscopy with Fourier transform (FT-IR) which was used to confirm the structure of the polymer, i.e. the success of the synthesis of PVAC by emulsion polymerization of vinyl-acetate, followed by differential scaning calorimetry (DSC) which gave insight into the thermal properties of PVAC and thermogravimetric analysis (TG) which gave insight into the thermal decomposition of PVAC. Comparing the FT-IR spectrograms of the original and synthesized PVAC, a correlation coefficient of 87.7% was obtained and this value is not big enough to confirm that it is indeed PVAC, but it showed characteristic vibration bands for pure PVAC with a slight deviation, which proves that PVAC has been successfully synthesized. DSC normalized curves confirm the conclusions obtained by FT-IR, but based on values of glass transition. By overlapping the DTG curves, the same conclusion is reached, close results in the decomposition steps confirmed that the synthesis of PVAC by emulsion polymerization of vinyl acetate has been successfully carried out
Food aditives : bachelor thesis
No full textPrehrambeni aditivi su tvari poznatog sastava, nisu hrana, već se dodaju namirnicama tijekom proizvodnje, transporta, oblikovanja, prerade i čuvanja hrane. Dodavanjem aditiva u hrani postiže se ujednačenost kvalitete proizvoda, produžuje se rok trajanja hrane tako što se sprječava kvarenje hrane. Prema porijeklu aditivi se dijele na aditive prirodnog porijekla i umjetne (sintetizirane) aditive. Prema funkcionalnosti, aditivi se dijele u 26 različitih kategorija koje su opisane u ovome radu. Kako bi se određeni aditiv svrstao na listu aditiva, potrebno je utvrditi potencijalni štetni učinak i podvrgnuti ih toksikološkoj provjeri. Da bi se potrošač direktno informirao o hrani koju kupuje i aditivima koji su joj dodani, uveden je E- sistem označavanja aditiva. Spomenutim sistemom svaki aditiv je označen s njemu pripadajućim brojem. Uporaba aditiva u Republici Hrvatskoj zakonski je regulirana Pravilnikom o prehrambenim aditivima NN 62/2010 s izmjenama i dopunama Pravilnika NN 62/2011, 135/2011 i 79/2012 te Zakonom o prehrambenim aditivima, aromama i prehrambenim enzimima NN 39/2013 s izmjenama Zakona NN 114/2018. Ako prehrambeni proizvod sadrži aditiv koji nije propisan pravilnikom ili se utvrdi veća količina aditiva, Ministarstvo poljoprivrede obavještava potrošača te sukladno tome slijedi povlačenje i/ili opoziv proizvoda s tržišta. Uporaba aditiva te primjena zakona u vidu opoziva proizvoda prikazana je na konkretnom primjeru hrenovki. U sklopu završnog rada obavljena je i anketa pod nazivom „Istraživanje poznavanja prehrambenih aditiva u općoj populaciji u Republici Hrvatskoj“ kako bi se dao uvid poznavanja samog pojma ''prehrambeni aditivi'' te kakav je stav ispitanika pri kupnji prehrambenih proizvoda koji sadrže aditive.Food additives are substances of known composition, they are not food, but are added to foods during the production, transport, shaping, processing and storage of food. The addition of food additives achieves uniformity of product quality, prolongs the shelf life of food by preventing food spoilage. According to the origin, additives are divided into additives of natural origin and artificial (synthesized) additives. According to functionality, additives are divided into 26 different categories that are described in this paper. In order for a particular additive to be included in the list of additives, it is necessary to determine the potential adverse effects and subject them to toxicological testing. In order for the consumer to be directly informed about the food he buys and the additives added to it, an E-labeling system for additives has been introduced. With the mentioned system, each additive is marked with its corresponding number. The use of additives in the Republic of Croatia is legally regulated by the Ordinance on food additives OG 62/2010 with amendments to the Ordinance OG 62/2011, 135/2011 and 79/2012 and the Act on food additives, flavorings and food enzymes OG 39/2013 with amendments to the Act NN 114/2018. If the food product contains an additive that is not prescribed by the ordinance or a larger amount of additive is determined, the Ministry of Agriculture informs the consumer, and accordingly the withdrawal and/or recall of the product from the market follows. As part of the final work, a survey entitled "Research on the knowledge of food additives in the general population in the Republic of Croatia" was conducted to provide insight into the knowledge of the term "food additives" and what is the attitude of respondents when buying food products containing additives
Electrochemical behavior of catechin on carbon nanomaterials: a contribution to the optimization of electroanalytical methods for determination of natural reducers : diploma thesis
No full textU ovom radu izvršena je modifikacija elektrode od staklastog ugljika sa različitim ugljikovim nanomaterijalima (grafen, elektrokemijski reducirani grafenov oksid, jednozidne ugljikove nanočestice, višezidne ugljikove nanočestice). Ispitano je elektrokemijsko ponašanje modificiranih i elektrokemijski funkcionaliziranih elektroda u prisutnosti katehina u tri različita pufera (acetatni pufer, Britton-Robison pufer, model otopine vina), te pri različitim pH vrijednostima (2,6-3,6 u Britton-Robinson puferu). Elektrokemijsko ponašanje katehina je određivano u različitim puferima metodama cikličke voltametrije i elektrokemijske impedancijske spektroskopije (EIS). Prikazan je utjecaj različitog broja ciklusa, kao i ovisnost visine anodnog strujnog pika o brzini posmika i njegovu korijenu u različitim puferima, te utjecaj različitih pH vrijednosti. Uočena je znatna ovisnost elektrokemijskog ponašanja katehina na modificiranim elektrodama u ovisnosti o puferu u kojima su mjerenja vršena. Nakon provedenih mjerenja objašnjen je mehanizam elektrokemijskih reakcija, ponašanje elektroda u različitim puferima, te ograničenja i problemi vezani za elektrokemijsko ponašanje. Kao najoptimalniji sustav za određivanje katehina, na osnovu analize, isprofilirale su se elektrode modificirane s ugljikovim nanocijevčicama u Britton-Robinson puferu, pri pH vrijednosti 3,6 i ErGO u otopini modela vina.In this diploma thesis, a modification of a glassy carbon electrode with different carbon nanomaterials as modifications (graphene, electrochemically reduced graphene oxide, single-walled carbon nanoparticles and multi-walled carbon nanoparticles) was investigated. The electrochemical behavior of modified and electrochemically functionalized electrodes in the presence of catechin in three different buffers (acetate buffer, Britton-Robinson buffer and wine solution model) and at different pH values (2.6- 3.6 in Britton-Robinson buffer) was examined. The electrochemical behavior of catechin was determined in different buffers by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) methods. The influence of different number of cycles is shown, as well as the dependance of the height of the anode current peak on the shear rate and its root in different pH values. A significant dependance of the electrochemical behavior of catechin on modified electrodes was observed depending on the buffer in which the measurments were performed. After the measurments were done, the mechanism of electrochemical reactions, the behavior of the electrodes in different buffers, the limitations and problems related to electrochemical behavior were explained. Based on analysis, as the most optimal system for the determination of catechin, electrodes modified with carbon nanotubes in Britton-Robinson buffer, at pH 3.6 and ErGO in the model wine solution were profiled