Title Određivanje tiabendazola koristeći senzor s funkcionaliziranim ugljikovim nanocjevčicama
Title (english) Determination of thiabendazole using sensor with functionalized carbon nanotubes
Author Ivana Novak
Mentor Mirela Samardžić (mentor)
Mentor Mateja Budetić (pomoć pri izradi, neposredni voditelj)
Committee member Marija Jozanović (predsjednik povjerenstva)
Committee member Mirela Samardžić (član povjerenstva)
Committee member Elvira Kovač-Andrić (član povjerenstva)
Granter Josip Juraj Strossmayer University of Osijek Department of Chemistry (Department of Analytical, Organic and Applied Chemistry) Osijek
Defense date and country 2022-10-07, Croatia
Scientific / art field, discipline and subdiscipline NATURAL SCIENCES Chemistry Analytic Chemistry
Abstract Tiabendazol (TBZ) je derivat benzimidazola koji ima široku primjenu kao fungicid. Koristi se za suzbijanje bolesti voća i povrća kao što su plijesan, trulež, plamenjača i mrlje. Veliku primjenu ima kod banana i agruma za održavanje svježine te kao komponenta voska koji se nanosi na voće. Sukladno navedenom, najviše se zadržava u kori voća. TBZ ima nisku toksičnost ali je klasificiran kao kancerogen kod većih doza te može izazvati poremećaj u radu štitnjače. U ljudskom organizmu prilikom konzumacije voća i povrća tretiranih tiabendazolom, sukladno postojećim propisima, nakuplja se koncentracija TBZ nedovoljna da izazove rak. Najčešće korištene metode za određivanje TBZ su kromatografske metode, Ramanova spektroskopija, UV/Vis spektrofotometrija, fosforometrija i imunotest. Većina navedenih metoda iziskuje skupu opremu, korištenje velikih količina organskih otapala te komplicirane procedure i pripreme uzoraka. S obzirom na navedeno, korištenje ionsko selektivnih elektroda (ISE) je dobra alternativna metoda zbog jednostavnosti njihove pripreme i primjene te dobrih analitičkih preformansi. Takve elektrode najčešće sadrže tekuću membranu koja sadrži senzorski materijal, plastifikator i polivinil klorid. Glavni nedostatak elektroda s tekućom membranom je mogućnost istjecanja senzorskog materijala. Navedeni nedostatak dovodi do promjena karakteristika samog senzora, a time i smanjenja radnog vijeka senzora. Kako bi se izbjegli navedeni nedostatci, moguće je koristiti senzore s čvrstim kontaktom (engl. solid state) ili modificirati sastav membrane koristeći senzorske materijale koji su manje topljivi u vodi. Nanomaterijali bazirani na ugljiku su se pokazali vrlo pogodnim za tu svrhu. Modifikacija senzorskog materijala s višestjenčanim ugljikovim nanocjevčicama (engl. multi-walled carbon nanotubes, MWCNT) rezultira boljim odzivnim karakteristikama senzora, manjim ispiranjem senzorskog materijala
iz membrane te manjim šumom signala. MWCNT se mogu kovalentno modificirati zadržavajući svoja inicijalna svojstva te na taj način formirati hibridni senzorski materijal. Direktna potenciometrijska mjerenja, koristeći senzore s čvrstim kontaktom i tekućom membranom modificiranom MWCNT, imaju veliki potencijal za određivanje TBZ zbog jednostavnosti metode te jednostavne primjene, točnosti i dugotrajnosti takvih senzora.
U ovom radu korišten je novi potenciometrijski senzor s čvrstim kontaktom i tekućom membranom za određivanje TBZ. Kao senzorski materijal novog senzora korišten je hibridni materijal temeljen na MWCNT modificiranim sulfatnom skupinom i TBZ ionom. Senzor je pokazao Nernstovski odziv na TBZ (60,4 mV/dekada aktiviteta) u mjernom području između 8.6 ∙ 10-7 i 1.0 ∙ 10-3 M. Granica detekcije za TBZ je bila 6.2 ∙ 10-7 M dok je vrijeme odziva senzora na TBZ bilo 8 s. Tijek signala (engl. signal drift) iznosio je 1.7 mV/h. Mjerno pH područje senzora bilo je između 2 i 4, što nije predstavljalo ograničenje za korištenje senzora jer je TBZ topiv tek pri pH 2.6. Senzor je uspješno primijenjen za izravno potenciometrijsko određivanje TBZ-a u čistim otopinama te u složenim realnim uzorcima (kora naranče, limuna, banane, klementine i limete). Točnost senzora potvrđena je metodom standardnog dodatka. Vrijeme trajanja senzora, uz svakodnevno korištenje bilo je oko tri mjeseca.
Abstract (english) Thiabendazole (TBZ) is a benzimidazole derivative that is widely used as a fungicide. It is used to control fruit and vegetable diseases such as mold, rot, blight and spots. It is widely used in bananas and citrus fruits to maintain freshness and as a component of wax that is applied to the fruit. According to the above, it is mostly retained in the fruit peel. TBZ has low toxicity, but it is classified as a carcinogen at higher doses and can cause thyroid disorders. In the human body, when consuming fruits and vegetables treated with TBZ, in accordance with existing regulations, a concentration of TBZ will be insufficient to cause cancer. The most commonly used methods for TBZ determination are chromatographic methods, Raman spectroscopy, UV/Vis spectrophotometry, phosphorimetry and immunoassay. Most of the mentioned techniques require expensive equipment, the use of large amounts of organic solvents, and complicated procedures and sample preparations. Considering the above, the use of ion selective electrodes (ISE) is a good alternative method due to the simplicity of their preparation, application and good analytical performance. Such electrodes usually contain a liquid membrane containing sensor material, plasticizer and polyvinyl chloride. The main disadvantage of electrodes with a liquid membrane is the possibility of leakage of the sensor material. The aforementioned deficiency leads to changes in the characteristics of the sensor itself and shortened lifetime of the sensor. In order to avoid the mentioned shortcomings, it is possible to use solid-state sensors or to modify the composition of the membrane using sensor materials that are as less soluble as possible in water. Carbon-based nanomaterials have proven to be very suitable
for this purpose. Modification of the sensor material with multi-walled carbon nanotubes (MWCNT) results in better response characteristics of the sensor, less leaching of the sensor material from the membrane and less signal noise. MWCNTs can be covalently modified while retaining their initial properties, thus forming a hybrid sensor material. Direct potentiometric measurements, using sensors with a solid contact and a liquid membrane modified with MWCNT, have great potential for TBZ determination due to the simplicity of the method and the simple application, accuracy and durability of such sensors.
In this work, a new potentiometric solid-state sensor with a liquid membrane was used to determine TBZ. A hybrid material based on MWCNT modified with sulfate group and TBZ ion was used as the sensor material of the new sensor. The sensor showed a Nernstian response for TBZ (60.4 mV/decade of activity) in the measuring range between 8.6 ∙ 10-7 and 1.0 ∙ 10-3 M. The detection limit for TBZ was 6.2 ∙ 10-7 while the response time of the sensor for TBZ was 8 s. The signal drift was 1.7 mV/h. The measuring pH range of the sensor was between 2 and 4, which was not a limitation for the use of the sensor because TBZ is soluble only at pH 2.6. The sensor was successfully applied for direct potentiometric determination of TBZ in pure solutions and in complex real samples (peel of orange, lemon, banana, clementine and lime). The accuracy of the sensor was confirmed using the standard addition method. The lifetime of the sensor, with daily use, was approximately three months.
Keywords
direktna potenciometrija
senzor s čvrstim kontaktom
tiabendazol
Keywords (english)
direct potentiometry
solid-state sensor
thiabendazole
Language croatian
URN:NBN urn:nbn:hr:182:698996
Study programme Title: Graduate University Study of Chemistry; educational program; specializations in: Educational program Course: Educational program Study programme type: university Study level: graduate Academic / professional title: magistar/magistra edukacije kemije (magistar/magistra edukacije kemije)
Type of resource Text
File origin Born digital
Access conditions Open access
Terms of use
Public note Rezultati diplomskog rada publicirani su u časopisu Sensors:
Dandić, Andrea, Ivana Novak, Marija Jozanović, Iva Pukleš, Aleksandar Széchenyi, Mateja Budetić, and Mirela Samardžić. 2022. "A New, MWCNT-Based, Solid-State Thiabendazole-Selective Sensor" Sensors 22, no. 10: 3785. https://doi.org/10.3390/s22103785
Created on 2022-11-02 11:36:01