Priprema Cu(II)/politiraminskog kompleksa kao katalizatora za mjerenje koncentracije askorbinske kiseline

master's thesis

• Title (english): Preparation of polytyramine Cu(II) complex layer as a catalyst for ascorbic acid determination
• Author: Alen Đalapa
• Mentor: Stjepan Milardović (mentor)
• Committee member: Stjepan Milardović (predsjednik povjerenstva)
• Committee member: Ema Horak (član povjerenstva)
• Committee member: Marijana Kraljić Roković (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2017-09-25, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry; Inorganic Chemistry

Abstract

U ovom radu izvedena je priprema Cu(II)/politiraminskog kompleksa kao katalizatora za mjerenje koncentracije askorbinske kiseline, modificiranjem zlatne (Au) elektrode politiraminom i naknadnim kompleksiranjem politiramina bakrom. Ciklička voltametrija korištena je kao glavna tehnika za pripremu i karakterizaciju elektrode. Sloj politiramina nanesen je na zlatnu elektrodu elektropolimerizacijom tiramina iz 2,5 mM otopine tiramina pripravljene u fosfatnom puferu pH=4,10. Naneseno je ukupno 20 slojeva polimera. Cu(II)/politiraminski kompleks pripremljen je uranjanjem Au-PTy modificirane elektrode u 1 mM otopinu bakrovih iona pripravljenu u HEPES puferu pH=8. Akumulacija bakra provedena je u trajanju od 20 minuta, nakon čega je elektroda temeljito isprana deioniziranom vodom. Provedena su mjerenja odziva zlatne te modificiranih Au-PTy i Au-PTy-Cu elektroda uz promjenu koncentracije askorbinske kiseline, te su u rezultatima prikazane njihove usporedbe. Provjerena je stabilnost Au-PTy-Cu modificirane elektrode. Napravljena je optimizacija vremena akumulacije bakra, pH medija pogodnog za akumulaciju bakra, te broja slojeva politiramina nanesenih na površinu zlatne elektrode. Oslojavanjem zlatne elektrode politiraminom uspješno je uklonjeno interferiranje mokraćne kiseline te je tako omogućeno mjerenje koncentracije askorbinske kiseline. Modifikacijom Au-PTy elektrode bakrom dolazi do pojave katalitičkog efekta koji se očituje u procesu oksidacije askorbinske kiseline. Stabilnost Au-PTy-Cu modificirane elektrode smanjuje se s vremenom stajanja na zraku i uzastopnim mjerenjem. Za mjerenje koncentracije askorbinske kiseline uočeno je optimalno vrijeme akumulacije bakra od 20 minuta u blago lužnatom mediju (pH=8).

Abstract (english)

In this thesis Cu(II)/polytyramine complex is prepared as a catalyst for determination of ascorbic acid by modification of a gold electrode with polytyramine and further modification by copper complexation. Cyclic voltammetry is used as the main technique for preparation and characterization of the electrode. Polytyramine layer is deposited on the gold electrode with electropolymerization of tyramine from 2,5 mM solution of tyramine and phosphate buffer pH=4,10. Altogether 20 layers of polytyramine is deposited on the gold electrode. Cu(II)/polytyramine complex is prepared by immersion of Au-PTy modified electrode into a 1 mM solution of copper ions prepared in HEPES buffer pH=8. Accumulation is carried out for 20 minutes, after which the electrode was thoroughly washed with deionized water. Responses of Au, Au-PTy and Au-PTy-Cu electrodes are measured with changing concentrations of ascorbic acid and comparisons of these measurements is shown in the results section. Stability of the Au-PTy-Cu modified electrode is tested. Optimization of time of copper accumulation, pH of solution from which copper is accumulated and number of polytyramine layers deposited on gold electrode was carried out. With deposited polytyramine on the gold electrode the interference of uric acid with ascorbic acid is removed, thus enabling measurement of ascorbic acid. Modified Au-PTy electrode with copper shows catalytic effect on oxidation of ascorbic acid. Stability of Au-PTy-Cu modified electrode decreases with time of the electrode being exposed to air and its repeated use. Optimal time of accumulation of copper is 20 minutes and optimal pH of solution from which copper is accumulated is pH= 8.

• Keywords: bakar(II); zlatna elektroda; modificirana elektroda; politiramin; ciklička voltametrija; askorbinska kiselina
• Keywords (english): copper(II); gold electrode; modified electrode; polytyramine; cyclic voltammetry; ascorbic acid
• Language: croatian
• URN:NBN: urn:nbn:hr:149:097064
• Study programme: Title: Chemical Engineering - Graduate study; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka kemijskog inženjerstva (magistar/magistra inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2020-04-22 09:52:17