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Title:Razvoj metod za določanje organskih molekul z uporabo modificiranih in nemodificiranih sitotiskanih ogljikovih elektrod : doktorska disertacija
Authors:ID Majer, David (Author)
ID Finšgar, Matjaž (Mentor) More about this mentor... New window
Files:.pdf DOK_Majer_David_2024.pdf (25,18 MB)
MD5: AD24DD4909EA765C0181221C4646DB34
 
Language:Slovenian
Work type:Doctoral dissertation
Typology:2.08 - Doctoral Dissertation
Organization:FKKT - Faculty of Chemistry and Chemical Engineering
Abstract:Kvalitativna in kvantitativna analiza organskih molekul v različnih vzorcih je ključnega pomena za zagotavljanje varnosti, učinkovitosti, skladnosti z zakonodajo in kakovostjo na področjih okoljskega varstva, zdravstva ter živilske in farmacevtske industrije. V doktorski disertaciji so predstavljene novo razvite elektroanalizne metode z nemodificiranimi in modificiranimi sitotiskanimi ogljikovimi elektrodami (SPCE) za določanje epinefrina (EP), sečne kisline (UA), metil parationa (MP) in inzulina (IN) v različnih realnih vzorcih, kot so zdravila, človeški urin in pitna voda. Pri prvi razviti metodi smo pokazali individualno določanje EP in UA, ki je potekalo z nemodificiranim SPCE-senzorjem, kjer smo razvili elektroanalizno metodo z analizo ene kapljice raztopine (50 µL). Linearni regresijski model smo ovrednotili z uteženo metodo najmanjših kvadratov, ki je izboljšala točnost pri nizkih koncentracijah linearnega koncentracijskega območja za oba analita v primerjavi z metodo najmanjših kvadratov. Razviti in validirani metodi sta bili uspešno uporabljeni za določanje EP v zdravilu (injekcijski peresnik) in UA v človeškem urinu. Razvoj druge elektroanalizne metode smo izvedli tako, da smo z L-cisteinsko kislino (LCA) modificirali površino SPCE-senzorja (LCA-SPCE), kar je omogočilo določanje pesticida MP v vzorcu pitne vode. Uspešno elektronalaganje LCA na površino delovne elektrode LCA-SPCE-senzorja smo potrdili s tehniko masne spektrometrije sekundarnih ionov z analizatorjem na čas preleta (ToF-SIMS). Prisotnost LCA na površini delovne elektrode SPCE-senzorja je signifikantno povišala signal tehnike angl. square-wave (SW) voltametrije, kar omogoča določanje MP v sledovih. Razvita metoda je vključevala postopek odštevanja ozadja, ki je pripomogel k povišanju analitskega signala. S tehniko elektrokemijske impedančne spektroskopije smo pojasnili povišanje signala MP na LCA-SPCE-senzorju. Pri razvoju tretje elektroanalizne metode smo na površino SPCE-senzorja naložili poli-L-cisteinsko (pLC)-plast in ta pLC-SPCE-senzor uporabili za simultano določanje EP in UA. Uspešno elektronalaganje L-cisteina (LC) na površino delovne elektrode SPCE-senzorja smo potrdili s tehniko ToF-SIMS. Za ta senzor smo izvedli optimizacijo različnih SW-parametrov (amplituda, potencialni korak, frekvenca), pH pomožnega elektrolita, čas elektronalaganja, potencial elektronalaganja, množinske koncentracije LC in števila ciklov elektropolimerizacije LC z namenom dosega najboljše elektroanalizne zmogljivosti pLC-SPCE-senzorja. Pod optimiziranimi pogoji smo izvedli validacijo analizne metode za simultano določanje EP in UA. Prav tako smo izvedli študijo interferenc, ki so lahko potencialno prisotne v testiranih realnih vzorcih. Razvit in validiran pLC-SPCE-senzor smo uspešno uporabili za določanje EP v injekcijskem peresniku in UA v človeškem urinu. V četrti študiji smo razvili elektroanalizno metodo za določanje klinično pomembnega biomarkerja IN. Uporabili smo SPCE-senzor, ki smo ga modificirali z molekularno vtisnjenim polimerom (MIP). Razvoj MIP-SPCE-senzorja je potekal tako, da smo najprej elektropolimerizirali pirol v prisotnosti IN. Nato smo iz nastale polipirolne plasti odstranili molekule IN in s tem tvorili praznine z vezavnimi mesti za molekule IN. Odstranjevanje IN smo izvedli s pomočjo elektročiščenja s ciklično voltametrijo. Nato je sledila inkubacija molekul IN, ki so se vezale na tvorjena vezavna mesta na MIP-SPCE-senzorju. Določanje IN z razvitim MIP-SPCE-senzorjem je potekalo z analizo ene kapljice raztopine, ki je vsebovala redoks probo [Fe(CN)6]3‒/4‒. Elektroanalizno metodo z razvitim MIP-SPCE-senzorjem smo validirali in pokazali njeno uporabo za določanje IN v zdravilu (injekcijski vložek).
Keywords:epinefrin, sečna kislina, metil paration, inzulin, sitotiskana ogljikova elektroda, senzor
Place of publishing:Maribor
Place of performance:Maribor
Publisher:[D. Majer]
Year of publishing:2024
Number of pages:XIII, 130 str.))
PID:20.500.12556/DKUM-86968 New window
UDC:543.55:543.63(043.3)
COBISS.SI-ID:201110787 New window
Publication date in DKUM:27.06.2024
Views:465
Downloads:270
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FKKT
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Licences

License:CC BY 4.0, Creative Commons Attribution 4.0 International
Link:http://creativecommons.org/licenses/by/4.0/
Description:This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
Licensing start date:01.02.2024

Secondary language

Language:English
Title:Method development for the determination of organic molecules using modified and unmodified screen-printed carbon electrodes
Abstract:The qualitative and quantitative analysis of organic molecules in various samples is crucial to ensuring safety, efficacy, regulatory compliance, and quality in the fields of environmental protection, healthcare, and the food and pharmaceutical industries. In the doctoral dissertation, newly developed electroanalytical methods are presented using unmodified and modified screen-printed carbon electrodes (SPCE) for the determination of epinephrine (EP), uric acid (UA), methyl parathion (MP), and insulin (IN) in various real samples, such as drugs, human urine, and drinking water. In the first method developed, the individual determination of EP and UA was demonstrated using an unmodified SPCE sensor, and an electroanalytical method was developed with single-drop analysis of the solution (50 µL). The linear regression model was evaluated using the weighted least squares method, which improved the accuracy at low concentrations of the linear concentration range for both analytes, compared to the ordinary least squares method. The developed and validated methods were successfully used for the determination of EP in a drug (an autoinjector) and UA in human urine. In the development of the second electroanalytical method, the surface of the SPCE sensor was modified with L-cysteic acid (LCA), which enabled determination of the pesticide MP in a drinking water sample. The successful electrodeposition of LCA on the working electrode of the LCA-SPCE sensor was confirmed by the time-of-flight secondary ion mass spectrometry (ToF-SIMS) technique. The signal of the square-wave (SW) voltammetry technique was significantly enhanced by the presence of LCA on the working electrode of the SPCE sensor, which enabled the analysis of MP in trace amounts. The method developed included a background subtraction process that enhanced the analytical signal. Electrochemical impedance spectroscopy was used to clarify the signal enhancement of MP on the LCA-SPCE sensor. In the development of the third electroanalytical method, a poly-L-cysteine (pLC) layer was electrodeposited on the surface of the SPCE sensor, and this pLC-SPCE sensor was used for the simultaneous determination of EP and UA. The successful electrodeposition of L-cysteine (LC) on the working electrode of the SPCE sensor was confirmed using the ToF-SIMS technique. Various SW parameters (amplitude, potential step, frequency), the pH of the supporting electrolyte, the electrodeposition time, the electrodeposition potential, the molar concentrations of LC, and the number of cycles of LC electropolymerization were optimized to achieve the best electroanalytical performance of the pLC-SPCE sensor. Under these optimized conditions, the analytical method for the simultaneous determination of EP and UA was validated. A study of interferences that could be present in the tested real samples was also performed. The developed and validated pLC-SPCE sensor was successfully used for the determination of EP in an autoinjector and UA in human urine. In the fourth study, an electroanalytical method for determining the clinically important biomarker IN was developed. An SPCE sensor, modified with a molecularly imprinted polymer (MIP), was used. In the development of the MIP-SPCE sensor, pyrrole was electropolymerized in the presence of IN. Then, IN molecules were removed from the formed polypyrrole layer, creating cavities with binding sites for IN molecules. The removal of IN was carried out using electrocleaning with cyclic voltammetry. The binding of IN molecules to the formed binding sites on the MIP-SPCE sensor was then achieved by incubation. The determination of IN with the developed MIP-SPCE sensor was performed using single-drop analysis of the solution containing a redox probe [Fe(CN)6]3‒/4‒. The electroanalytical method using the developed MIP-SPCE sensor was validated and its application for the determination of IN in a drug (a cartridge) was demonstrated.
Keywords:epinephrine, uric acid, methyl parathion, insulin, screen-printed carbon electrode, sensor


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