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Spectrophotometric determination of biologicall active substances in pharamceutical preparations - review : bachelor thesis
No full textUltraljubiĉasta i vidljiva apsorpcijska spektroskopija primjenjuje se za kvantitativnu, ali i kvalitativnu analizu. To je najĉešće primjenjivana metoda u kemijskim i kliniĉkim laboratorijima. Temelji se na ovisnosti energije zraĉenja i kemijskog sastava tvari. Farmaceutici su proizvodi koji se primjenjuju u korist primatelja radi istraţivanja ili modificiranja fizioloških sustava ili lijeĉenja patoloških stanja. Primjenjuju se kako bi se sprijeĉila ili lijeĉila bolest ili simptomi bolesti. U ovom radu vidljiv je pregled dostupne literature o odreĊivanju bioloških aktivnih tvari u farmaceutskim pripravcima.Ultraviolet and visible absorption spectroscopy is used for quantitative as well as qualitative analysis. It is the most commonly used method in chemical and clinical laboratories. It is based on dependence of radiation energy and chemical composition of matter. Pharmaceutical preparations are substances used in favor of primary radiological researches, modification of physiological systems or treatment of pathological conditions. They are used to prevent or to treat diseases and its symptoms. This bachelor thesis provides an overview of the available literature on the determination of biologically active substances in pharmaceutical preparations
Phenolic composition and antioxidant effect of sour cherry juice : bachelor thesis
No full textZbog velike prehrambene vrijednosti i bogatog udjela bioaktivnih komponenti koje pozitivno utječu na zdravlje i održavaju normalno funkcioniranje organizma, voće čini sastavni dio ljudske prehrane. Među brojnim vrstama voća posebno se izdvaja višnja, voće poznato po velikoj količini antioksidansa. Jedna od najpoznatijih sorti višnje u Dalmaciji je višnja Maraska koja ima visoku nutritivnu vrijednost i dobar biološki učinka na ljudsko zdravlje. U ovom radu ispitan je fenolni sastav i antioksidacijska aktivnost matičnog soka višnje Maraske i soka s dodatkom konoplje. Određivani su slijedeći parametri: boja soka, ukupni fenoli, flavonoidi i neflavonoidi (Folin-Ciocalteu metodom), antocijani (metodom izbjeljivanja s bisulfitom) te antioksidacijska aktivnost (metodom određivanja redukcijske aktivnosti - FRAP i sposobnost hvatanja molekula slobodnog radikala 2,2-difenil-1-pikrilhidrazil - DPPH). Dodatak ekstrakta industrijske konoplje u soka od višnje nije značajno utjecao na poboljšanje antioksidacijske aktivnosti kao ni na fenolni sastav matičnog soka. Rezultati ukazuju na veći udio ukupnih fenola (5630,56 mg GAE/L) i antocijana (2858.33 mg cijanidina/L) u čistom matičnom soku u odnosu na sok s dodatkom konoplje (5486,11 mg GAE/L ukupnih fenola i 2352.58 mg cijanidina/L). Redukcijska snaga čistog soka bila je znatno veća, dok je sok s dodatkom konoplje pokazao neznatno bolju sposobnost hvatanja radikala. Dobiveni rezultati ukazuju na bogat fenolni sastav i antioksidacijski potencijal matičnog soka višnje Maraske bez dodataka i s dodatkom konoplje.The fruits are an integral part of human diet due to its nutritional value and large number of bioactive components with positive beneficial effect on human and normal functioning of the organism. Among numerous types of fruit, the cherries stand out as rich source of antioxidants. One of the most known in Dalmatia is Maraska cherry variety, popular for its high nutritional value and good biological effect on human health. In this paper the phenolic composition and antioxidant activity of pure Maraska sour cherry juice and a juice with addition of hemp extract were examined. The juice colour parameters, total phenols, flavonoids and non-flavonoids (Folin-Ciocalteu method), anthocyanins (by bisulphite bleaching method) and antioxidant activity (by the method of determining the reducing activity-FRAP and the ability to capture free radical molecules 2,2-diphenyl-1-picrylhydrazyl-DPPH) were determined. The addition of industrial hemp extract to cherry juice did not significantly improve the antioxidant activity or the phenolic composition of the pure juice. The results indicated a higher proportion of total phenolics (5630,56 mg GAE/L) and anthocyanins (2858,33 mg cyanidin/L) in pure juice compared to the juice with hemp extract (5486,11 mg GAE/L of total phenols and 2352,58 mg cyanidin/L). The reducing power of the pure juice was significantly higher, while juice with the addition of hemp extract showed a slightly better ability to capture radicals. The results confirm that the pure Maraska cherry juice, with and without hemp, is a rich source of phenolics with strong antioxidant potential that can contribute to the overall health
Antioxidant potential of kale (Brassica oleracea L. var. acephala) extracts : diploma thesis
No full textRaštika (Brassica oleracea L. var. acephala) je autohtona hrvatska povrtna kultura, osobito popularna u južnom priobalju Dalmacije i susjedne Bosne i Hercegovine ali nažalost vrlo malo istražena. Razvojem znanosti i projektima koji se oslanjaju na popularizaciju autohtonih kultura, raštika danas postaje sve češće predmetom istraživanja zbog svog bogatog nutritivnog sastava i biološkog učinka na ljudsko zdravlje. U ovom radu ispitana je primjena različitih metoda ekstrakcije (ultrazvuk - UZV i mikrovalna - MAE), kao i otapala (voda i 50 %-tni etanol), na prinos ukupnih fenola u ekstraktima raštike s područja Hercegovine. Udio ukupnih fenola određen je spektrofotometrijskom Folin-Ciocalteu metodom, a antioksidacijska aktivnost ispitana je različitim metodama, ovisno o mehanizmu djelovanja: FRAP (Ferric-reducing antioxidant power), DPPH (2,2-Diphenyl-1- picrylhydrazyl assay) i ORAC (Oxygen radical absorbing capacity). Dobiveni rezultati ukazuju na bogatiji fenolni sastav ekstrakata pripravljenih korištenjem vode kao otapala kod obje metode ekstrakcije, UZV i MAE (250-270 mg GAE/L). Uspoređujući metode ekstrakcije istaknula se MAE metoda koja je u puno kraćem vremenu dala gotovo sličan prinos fenolnih komponenti u odnosu na UZV. Antioksidacijska aktivnost određena FRAP metodom bila je najbolja u vodenim ekstraktima, dok se kod ORAC i DPPH metode uočavaju veliku razlike u antioksidacijskoj aktivnosti osobito kod etanolnih uzoraka ekstrahiranih ultrazvukom i mikrovalovima. Dobiveni rezultati se nedvojbeno razlikuju, no svi ispitivani uzorci pokazuju izrazito dobar antioksidacijski potencijal i udio ukupnih fenola. Uzimajući u obzir da su razlike u rezultatima fenolnog sastava i antioksidacijske aktivnosti testiranih uzoraka vrlo male, kao najpovoljnija metoda ekstrakcije odabrana je mikrovalna upravo zbog kraćeg vremena provedbe ekstrakcije.Kale (Brassica oleracea L. var. acephala) is an autochthonous Croatian vegetable culture, especially popular in the southern coast of Dalmatia and neighboring Bosnia and Herzegovina, but unfortunately poorly researched. With the development of science and projects that rely on the popularization of indigenous cultures, raštika is now increasingly the subject of research due to its rich nutritional composition and biological effect on human health. In this paper, the application of different extraction methods (ultrasound - UZV and microwave - MAE), as well as solvents (water and 50% ethanol), on the yield of total phenols in extracts of kale from the territory of Herzegovina. The proportion of total phenols was determined by the Folin-Ciocalteu spectrophotometric method and antioxidant activity was tested with different methods, depending on the mechanism of action: FRAP (Ferric- reducing antioxidant power), DPPH (2,2-Diphenyl-1-picrylhydrazyl assay) and ORAC (Oxygen radical absorbing capacity). The obtained results indicate an abundant phenolic composition of extracts prepared using water as solvent in both extraction methods, ultrasound and MAE (250-270 mg GAE/L). Comparing the extraction methods, MAE method stood out, which in a much shorter time gave almost similar yields of phenolic components compared to ultrasound. The antioxidant activity determined by the FRAP method was the best in aqueous extracts, while the ORAC and DPPH methods showed large differences in antioxidant activity, especially in ethanol samples extracted by ultrasound and microwaves. The obtained results undoubtedly differ, but all tested samples show extremely good antioxidant potential and total phenolic contents. Considering that the differences in the results of phenolic composition and antioxidant activity of the tested samples was very small, the microwave was chosen as the most appropriate extraction method because of the shorter duration of extraction
Cytotoxic activity of sesquiterpene lactones cynaropicrin and costunolide : diploma thesis
No full textSeskviterpeni su prirodni kemijski spojevi koji su po svojoj kemijskoj strukturi C-15 terpenoidi. Pojavljuju se kao ugljikovodici ili u oksidiranoj formi kao alkoholi, aldehidi, kiseline ili laktoni u prirodi. Važni su sastojci biljnih ekstrakata i esencijalnih ulja koja imaju značajnu primjenu u medicinskim, mirisnim pripravcima ili sapunima. Seskviterpenski laktoni posjeduju značajna biološki aktivna svojstva koja mogu biti od iznimne koristi u liječenju mnogih bolesti. Mogu imati protuupalan, antitumorski, antimikrobni, učinak na živčani i kardiovaskularni sustav i druge biološke učinke. Od biološke aktivnosti značajan je njihov citotoksični, antitumorski učinak na ljudske stanice. Citotoksični učinak vezan je za α,β-nezasićenu karbonilnu strukturu kao što je α-metilen-γ-lakton, odnosno α,β-nezasićeni ciklopentanon ili konjugirani ester. Seskviterpenski laktoni cinaropikrin i kostunolid mogu se izolirati iz biljaka porodice Asteracea, posebno iz biljaka njezinog roda Centaurea. Dobro je poznat i značajan njihov citotoksični učinak dokazan u brojnim istraživanjima. U ovom radu tesitan je citotoksičan učinak seskviterpenskih laktona cinaropikrina i kostunolida na ljudske stanice fibroblaste. Pomoću MTT testa utvrđena je viabilnost stanica. Pokazali smo da je potrebno testirati koncentracije cinaropikrina više od 2,890 μM i kostunolida više od 21,500 μM kako bismo postigli vrijednosti inhibicije rasta stanica niže od 50%. Testiranja cinaropikrina pokazala su da manje koncentracije imaju i pozitivan učinak na rast stanica fibroblasta, te su potrebna dodatna istraživanja kako bismo utvrdili o kakvom se učinku i mehanizmu aktivacije radi.Sesquiterpenes are natural chemical compounds that are C-15 terpenoids by their chemical structure. They appear as hydrocarbons or oxidized form products as alcohols, aldehydes, acids or lactones in nature. They are important ingredients of plant extracts and essential oils that have significant application in medical, fragrant preparations or soaps. Sesquiterpene lactones own important biologically active properties that can be very useful in many disease treatments. They can have anti-inflammantory, antitumor, antimicrobial effects on central nervous and cardiovascular system as well as other biological effects. Of biological activities, cytotoxic, antitumor activity is significant on human cells. Cytotoxic activity is realted to α,β-unsaturated carbonyl structure such as α-methylene-γ-lactone or to α,β- unsaturated cyclopentanone or conjugated ester. Sesquiterpene lactones cynaropicrin and costunolide can be isolated from plants of Asteracea family, especially from plants of its genus Centaurea. Their cytotoxic activity is well known and proven in numerous studies. In this paper, the cytotoxic activity of cynaropicrin and costunolide sesquiterpene lacones was tested on human fibroblast cells. Cell viability was determined by MTT assay. We have shown that it is necessary to test higher concentrations of cynaropicrin of 2,890 μM and costunolide of 21,500 μM in order to achieve cell growth inhibition values lower than 50%. Cynaropicrin tests have shown that lower concentrations have positive effect on fibroblast cell growth and further research is needed in order to determine what the effect and mechanism of activation is
Enzymatic and microwawe assisted degradation of glucosinolates and their identification using breakdown and desulfated products : diploma thesis
No full textGlukozinolati su sekundarni metaboliti koji su zastupljeni u 16 botaničkih porodica reda Capparales, a najznačajnija je porodica Brassicaceae u koju se ubrajaju dobro poznate biljke iz svakodnevne prehrane kao što su kupus, brokula, cvjetača, prokulice, rotkvica, repa, gorušica i druge. Po kemijskoj strukturi to su β- tioglukozidni-N-hidroksisulfati s varijabilnim bočnim lancem. Glukozinolati su kemijski i biološki neaktivni. Enzimskom, kemijskom ili termičkom razgradnjom nastaje niz biološki aktivnih produkata od kojih su najviše istaživani izotiocijanati. U ovom radu primjenjene su različite metode izolacije uključujući hidrodestilaciju, autolizu te mikrovalnu destilaciju i ekstrakciju kako bi istražili termičku, enzimsku i mikrovalovima potpomognutu razgradnju glukozinolata. Posebno je zanimljiva mikrovalna ekstrakcija jer predstavlja pravi primjer zelene tehnologije. Cilj ovoga rada bio je izolirati i identificirati hlapljive sumporove spojeve iz sredozemne rusomače (Capsella bursa-pastoris L. Medik.), rotkvice (Raphanus sativus var. radicula Pers.), bijele rotkve (Raphanus sativus var. longipinnatus L.H. Bailey), čunjastog repušca (Bunias erucago L.) i sivkaste ljubičine (Matthiola inacana (L.) R. Br.). Za identifikaciju izoliranih spojeva korištene su GC-MS i HPLC-UV tehnike. U izolatima sredozemne rusomače identificiran je samo dimetil trisulfid. U izolatima rotkvice je preko razgradnih produkata identificiran glukodehidroerucin, a u bijeloj rotkvi glukodehidroerucin i glukoberteroin. U izolatima čunjastog repušca su preko desulfatiziranih produkata identificirani glukoerucin, glukonapin i glukotropeolin, a u sivkastoj ljubičini glukorafenin.Glucosinolates are secondary metabolites present in 16 botanical families of the Capparales Order, among which the most important is Brassicaceae family, which includes well-known plants of everyday nutrition such as cabbage, broccoli, cauliflower, broomsticks, radis, beets and others. Chemically these are β- thioglucoside-N-hydroxysulfates with a variable side chain. Glucosinolates are chemically and biologically inactive. Enzymatic, chemical, and thermal degradation result in formation of series of biologically active products, among which the most studied ones are isothiocyanates. In our study, we used different methods including hydrodistillation, autolysis followed by extraction, and microwave assisted distillation and extraction in order to investigate thermal, enzymatic, and microwave-assisted decomposition of glucosinolates. Microwave extraction is particularly interesting because it represents a true example of green technology. The aim of this study was to isolate and identify volatile sulfur compounds from the Capsella bursa-pastoris L. Medik., Raphanus sativus var. radicula Pers., Raphanus sativus var. longipinnatus L. H Bailey, Bunias erucago L. and Matthiola inacana (L.) R. Br.). GC-MS and HPLC-UV techniques were used to identify the isolated compounds. Only dimethyl trisulfide was identified in the isolates of the Capsella bursa-pastoris L. Medik. Glucodehydroerucin has been identified by the breakdown products in Raphanus sativus var. radicula Pers. and glucodehydroerucin and glucoberteroin in Raphanus sativus var. longipinnatus L. H Bailey. Glucoerucin, gluconapin and glucotropaeolin in Bunias erucago L. and glucoraphenin in Matthiola inacana (L.) R. Br. have been identified by their desulfated products
FePO4 : Ag2S : PTFE = 1 : 1 : 2 membrane response at 1 and 1,5 Ph values in FeCl3 i Fe(NO3)3 solutions : bachelor thesis
No full textOsnovni cilj ovoga rada je testiranje ionsko selektivnih membranskih elektroda kako bi pronašli membranu koja je selektivna na željezove (III) katione (Fe 3+ ) te da se s odgovarajućom membranom može odrediti kolika je koncentracija Fe 3+ kationa u nekoj otopini. Prethodno je obavljena priprava i dobivanje membrana a svaka od njih razlikuje se u svom sastavu odnosno u omjerima pripadajućih komponenata. Dakle, potrebno je ispitati učinkovitost membrane u procesu detekcije željezovih (III) kationa u otopini. Upravo to ispitivanje je područje ovoga rada koje se provodi u dvije osnovne otopine željezovog nitrata, odnosno željezovog klorida za njihov odziv na željezove katione. Temeljna provedba ovog ispitivanja je kontrola promjene potencijala s obzirom na promjenu koncentracije željezovih kationa. Pri tome testiranju također se mora voditi računa o pH otopine koji je kroz ispitivanja u oba slučaja imao vrijednost 1 i 1,50.The main object of this work is to test ion-selective membrane electrodes to find a membrane that is selective for iron (III) cations (Fe 3+ ), and to determine with a suitable membrane the concentration of Fe 3+ cations in a solution. The preparation and production of membranes has been done before, and each of them differs in its composition or in the proportions of its components. Therefore, it is necessary to investigate the efficiency of the membrane in the process of detecting ferric cations in solution. The basic implementation of this test is to control the change in potential with respect to the change in the concentration of iron cations. In this test, the pH of the solution, which in both cases had a value of 1 and 1,50, must also be taken into account
The vinegar fly - Drosophila suzukii in the area of Kastela vineyards : bachelor thesis
No full textDrosophila suzukii – octena mušica ploda je polifagni štetnik. Pojavila se 1916. godine u Japanu, a kasnije se proširila prekooceanskom i međunarodnom trgovinom te letom odraslih jedinki octene mušice ploda po Južnoj i Sjevernoj Americi te Europi. U Hrvatskoj je prvi put zapažena 2010. godine. D. suzukii uzrokuje značajne ekonomske štete na različitim voćnim kulturama te se kao posljedica toga javljaju ekonomski gubitci. Iako je razvijeno nekoliko metoda praćenja i suzbijanja octene mušice ploda, još uvijek nije razvijena metoda koja u potpunosti suzbija ovog štetnika. U kaštelanskom vinogorju D. suzukii uzrokuje zarazu bobica na grozdovima i prenosi kiselu trulež vinove loze uzrokovanu Acetobacter spp. koja zadaje velike probleme kaštelanskim vinogradarima.Drosophila suzuki - the vinegar fly is a polyphagous pest. It appeared in 1916 in Japan and later spread through overseas and international trade, and the flight of adult spotted wing drosophila throughout South and North America and Europe. It was first noticed in Croatia in 2010. D. suzukii causes signifficant economic damage to various fruit crops resulting in economic losses. Although several methods of survey and supression of the spotted wing drosophila have been developed, still an efficient method that completely supress this pest has not been developed. In vineyards of Kastela, D. Suzukii causes an infestation of grape berries and transmit acidic rotting of the grape vine caused by Acetobacter spp. which leads to great problems to the winegrowers
Testing of the teflon ration influence on the composition of ion-selective membranes in the determination of iron(III) cation : master thesis
No full textIspitan je odziv ionsko–selektivnih membrana na željezove(III) ione pri pH = 1 i pH =1,5, te utjecaj udjela teflona, kao neaktivnog nosača, na odziv samih membrana. Svako mjerenje je ponovljeno minimalno tri puta. Ispitivanje odziva izvršeno je potenciometrijski zbog jednostavnosti i praktičnosti metode, ali i njene pristupačne cijene. Selektivnost metode povećana je promjenom reakcijskih uvjeta, odnosno promjenom pH otopine uzorka. Membrane su se ispitivale u elektrokemijskoj ćeliji koristeći otopinu željezovog(III) klorida, pripremljenu u puferu sumporne kiseline, metodom slijednog razrjeđivanja. Za svako mjerenje zabilježena je vrijednost elektrodnog potencijala. Razrjeđivanje je trajalo dok razlika između dvaju mjerenja nije iznosila 1-2 mV.The main purpose of this thesis is testing the response of ion–selective membranes on iron (III) ions in pH = 1 and pH = 2, and Teflon part influence, as inactive carrier, on the composition of membranes. Each measurement was repeated minimum three times. The potentiometric method was used to test the response because of its simplicity and practicality, and also its affordable cost. The selectivity of the method is increased by changing the reaction conditions such as the pH of the sample solution. Membrane electrodes are tested for in electrochemical cell by using iron (III) chloride, prepared in sulfuric acid buffer, using sequentially dilution method. The value of the electrode potential was recorded for each measurement. Dilution was made until the potential difference between two measurements reached about 1-2 mV
Comparative study of volatile compounds of brandy Travarica : diploma thesis
No full textTravarica je jako alkoholno piće koje se tradicionalno proizvodi u južnim dijelovima Hrvatske. Travarice su specijalne rakije, aromatizirane biljnim ekstraktima. Za proizvodnju travarice najčešće se koriste rakije od grožđa, različiti macerati, perkolati, infuzi i drugi oblici ekstrakata ljekovitih biljaka. Biološki aktivni spojevi ljekovitog i aromatičnog bilja su eterična ulja, flavonoidi, tanini, saponini, sluzi i gorke tvari koje se ekstrahiraju u alkoholnu bazu pri sobnoj temperaturi. Uglavnom se kao alkoholna baza koristi rakija komovica. Cilj rada bio je usporedititi aromatski profil četiri različita uzorka travarica. Hlapljivi spojevi izolirani su pomoću mikroekstrakcije vršnih para na krutoj fazi (HS-SPME) i analizirani vezanim sustavom plinska kromatografija-masena spektrometrija (GC- MS). Usporedbom dobivenih rezultata utvrđen je različiti aromatski profil uzoraka. Dominantni spoj identificiran u svim uzorcima je etil-dekanoat. Uzorak rakije proizvođača "Vinoplod", pokazao je kompleksniji sastav u odnosu na ostale ispitane uzorke.Herbal brandy Travarica is a strong alcoholic beverage which is traditionally produced in southern parts of Croatia. Herbal brandies are special brandies, flavored with plant extracts. Grape brandies, various macerates, percolates, infusions and other forms of herbal extracts are most often used for the production of herbal brandies. Biologically active compounds of medicinal and aromatic herbs are essential oils, flavonoids, tannins, saponins, slippery secretion and bitter matters which are extracted into alcoholic base on ambient temperature. Komovica brandy is mostly used as an alcoholic base. The goal of this work was to compare aromatic profile od four different herbal brandy specimens. The volatile compounds were isolated by headspace solid-phase microextraction (HS-SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS). When comparing the obtained results, a different aromatic profile of specimens was found. Dominant compound identified in all the specimens is ethyl decanoate. The sample of brandy, produced by "Vinoplod" showed a more complex composition in relation to other tested samples
Electrochemical behavior of caffeic acid on carbon nanomaterials: a contribution to the optimization of electroanalytical methods for determination of natural reducers : diploma thesis
No full textU ovom radu su predstavljeni rezultati istraživanja ponašanja kofeinske kiseline na različito modificiranim elektrodama od staklastog ugljika. Elektrokemijska ispitivanja su vršena u tri različite puferske otopine (acetetnom, otopini model vina, Britton-Robinson puferu) te pri različitim pH vrijednostima (2,6 – 3,6 u Britton-Robinson puferu). Uočena je znatna ovisnost elektrokemijskog ponašanja kofeinske kiseline na modificiranim elektrodama u ovisnosti o puferu u kojima su mjerenja vršena. Kao najpogodniji pufer pokazao se Britton-Robinson pufer, dok su značajna kinetička ograničenja zabilježena u acetatnom pufer. Ove pojave su pripisane Frumkinovom efektu, koji je posebno naglašen na elektrodama modificiranim s ugljikovim nanocijevčicama. Nadalje, kinetička ograničenja vezana za prijenos elektrona kroz heterogenu granicu faza ispitivana su u širokom području brzina posmika. Na osnovu analize izračunati su koeficijenti prijelaza (α), kao i konstante brzine prijenosa elektrona za sve modificirane elektrode i u svim puferima. Povišenjem pH vrijednosti dolazi do pomaka potencijala strujnih pikova, ali i do smanjenja osjetljivosti. Ove pojave objašnjene su u kontekstu predloženih mehanizama oksidacije/redukcije kofeinske kiseline. Kao najoptimalniji sustav za određivanje kofeinske kiseline, na osnovu analize, isprofilirale su se elektrode modificirane ugljikovim nanocijevčicama u Britton-Robinson puferu, pri pH 3,6. Rezultati ovog diplomskog rada, zajedno s rezultatima dobivenim s drugim polifenolima na istim elektrodama mogu pomoći u prevladavanju interferencija, povećanju osjetljivosti i razvoju nove metode za određivanje polifenola u realnim uzorcima.This graduate thesis presents the results of research on the behavior of caffeic acid on variously modified glassy carbon electrodes. Electrochemical tests were performed in three different buffer solutions (acetate, wine model solution, Britton-Robinson buffer) at different pH values (2,6 – 3,6 in Britton-Robinson buffer). A significant dependence of the electrochemical behavior of caffeic acid on the modified electrodes was observed depending on the buffer in which the measurements were performed. Britton-Robinson buffer proved to be the most suitable buffer, while significant kinetic limitations were noted in acetate buffer. These phenomena are attribute to Frumkin effect, which is particularly pronounced on electrodes modified with carbon nanotubes. Furthermore, the kinetic constraints related to electron transfer across the heterogeneous phase boundary were investigated over a wide range of scan rates. Based on the analyses, the transition coefficients (α), and constant electron transfer rates for all modified electrodes in all buffers were calculated. Increasing the pH value shifts the potential of current peaks, but also reduces the sensitivity These phenomena are explained in the context of the proposed mechanisms of oxidation / reduction of caffeic acid. Based on analyses most optimal system for the determination of caffeic acids are modified electrodes with carbon nanotubes in Britton-Robinson buffer, at pH 3,6. The results of this thesis, together with the results obtained with other polyphenols on the same electrodes can help to overcome interference, increase sensitivity and develop new methods for the determination of polyphenols in real samples