BRNO UNIVERSITY OF TECHNOLOGY Faculty of Chemistry VRIJE UNIVERSITEIT BRUSSEL Faculty of Sciences and Bioengineering Sciences DOCTORAL THESIS 2020 Ing. Marek Reichstädter BRNO UNIVERSITY OF TECHNOLOGY FACULTY OF CHEMISTRY INSTITUE OF FOOD SCIENCE AND BIOTECHNOLOGY VRIJE UNIVERSITEIT BRUSSEL FACULTY OF SCIENCES AND BIOENGINEERING SCIENCES ANALYTICAL, ENVIRONMENTAL AND GEO- CHEMISTRY APPLICATION OF DIFFUSIVE GRADIENTS IN THIN FILMS TECHNIQUE IN FOOD- AND ENVIRONMENTAL ANALYSIS VYUŽITÍ TECHNIKY DIFÚZNÍHO GRADIENTU V TENKÉM FILMU V ANALÝZE POTRAVIN A V ENVIRONMENTALNÍ ANALÝZE DOCTORAL THESIS DISERTAČNÍ PRÁCE AUTHOR Ing. Marek Reichstädter AUTOR PRÁCE SUPERVISORS doc. Ing Pavel Diviš, Ph.D. ŠKOLITELÉ Prof. Dr. Yue Gao BRNO 2020 Doctoral Thesis Assignment Number of thesis: FCH-DIZ0193/2019 Academic year: 2019/20 Institute: Institute of Food Science and Biotechnology Student: Ing. Marek Reichstädter Study programme: Chemistry and Technology of Foodstuffs Study field: Food Science Head of thesis: doc. Ing. Pavel Diviš, Ph.D. Title of Doctoral Thesis: Application of diffusive gradients in thin films technique in food and environmental analysis Doctoral Thesis assignment: 1) Laboratory preparation of sorbent containing immobilized cysteine 2) Validation of DGT technique with binding gel containing laboratory prepared sorbent for determination of mercury event. other elements in the aqueous medium in conjunction with spectroscopic / spectrometric methods 3) Validation of DGT technique with binding gel containing Purolite S924 for determination of mercury event. other elements in the aqueous medium in conjunction with spectroscopic / spectrometric methods 4) Validation of new types of DGT for the determination of selected metals in liquid flavorings in conjunction with spectroscopic / spectrometric methods 5) Analysis of real samples using new types of DGT and spectroscopic / spectrometric methods 6) Publication of achieved results in journals wit impact factor Deadline for Doctoral Thesis delivery: 7. 8. 2020 Doctoral Thesis is necessary to deliver to a secretary of institute in the number of copies defined by the dean. This assignment is part of Doctoral Thesis. Ing. Marek Reichstädter doc. Ing. Pavel Diviš, Ph.D. prof. RNDr. Ivana Márová, CSc. Student Head of thesis Head of institute In Brno, 1. 9. 2019 prof. Ing. Martin Weiter, Ph.D. Dean Faculty of Chemistry, Brno University of Technology / Purkyňova 464/118 / 612 00 / Brno EXAMINATION COMMITTEE Promotors: Associate prof. Ing. Pavel Diviš, Ph.D. FCH, Brno University of Technology Prof. Dr. Yue Gao AMGC, Vrije Universiteit Brussel Other members: Prof. RNDr. Ivana Márová, CSc. FCH, Brno University of Technology Chairperson Prof. Dr. Frederik Tielens ALGC, Vrije Universiteit Brussel Secretary Prof. Dr. Martine Leermakers AMGC, Vrije Universiteit Brussel Associate prof. Ing. Stanislav Obruča, Ph.D. FCH, Brno University of Technology External members: Prof. Ing. Josef Čáslavský, CSc. CzechGlobe. Czech Academy of Sciences Associate prof. RNDr. Martin Urík, Ph.D. FNS, Comenius University in Bratislava Joint PhD between the Brno University Technology and the Vrije Universiteit Brussel. A dissertation submitted to the Brno University of Technology and the Vrije Universiteit Brussel, in partial fulfilment of the requirement for the double degree of Doctor (Ph.D.) from the Brno University of Technology and Doctor of Sciences from the Vrije Universiteit Brussel. 3 REICHSTÄDTER, Marek. Application of diffusive gradients in thin films technique in food- and environmental analysis. Brno, 2020. Also available at: https://www.vutbr.cz/studenti/zav- prace/detail/129384. Doctoral Thesis. Joint PhD of Brno University of Technology, Faculty of Chemistry, Institute of Food Science and Biotechnology and Vrije Universiteit Brussel, Faculty of Sciences and Bioengineering Sciences, Analytical, Environmental and Geo- Chemistry. Supervisors Pavel Diviš and Yue Gao. ACKNOWLEDGEMENTS Here, I would like to thank both supervisors for their help and advice, all my colleagues from both institutions for friendly work- and non-work environment and everyone who supported me throughout my PhD journey. Thank you. DECLARATION I declare that the doctoral thesis has been worked out by myself and that all the quotations from the used literary sources are accurate and complete. The content of the doctoral thesis is the property of the Faculty of Chemistry of Brno University of Technology and Faculty of Sciences and Bioengineering Sciences of Vrije Universiteit Brussel and all commercial use is allowed only if approved by both the supervisors and the deans of both institutions. …..…………………………… student's signature 4 TABLE OF CONTENTS Table of contents .............................................................................................................................. 5 List of Figures ................................................................................................................................... 7 Abbreviations ................................................................................................................................... 8 Summary ......................................................................................................................................... 10 Abstrakt .......................................................................................................................................... 11 Samenvatting .................................................................................................................................. 12 1 Introduction ............................................................................................................................... 13 1.1 General introduction .......................................................................................................... 13 1.2 References .......................................................................................................................... 14 2 Theoretical part ......................................................................................................................... 16 2.1 Trace elements ................................................................................................................... 16 2.1.1 Sources of trace elements in the environment ....................................................... 16 2.1.2 Biogeochemical cycle of trace elements ................................................................ 17 2.1.3 Human exposure to trace elements ........................................................................ 19 2.1.4 Trace elements in the foodstuffs ............................................................................ 20 2.1.5 Toxicity of trace elements ...................................................................................... 21 2.2 Methods for analysis of trace elements .............................................................................. 24 2.2.1 Spectroscopic and spectrometric methods ............................................................. 24 2.2.2 Electrochemical methods ....................................................................................... 26 2.2.3 Sample pre-treatment steps and specifics of trace elements analysis .................... 26 2.2.3.1 Environmental analysis specifics ................................................................ 27 2.2.3.2 Food analysis specifics ............................................................................... 29 2.2.4 Diffusive gradients in thin films technique ............................................................ 30 2.2.4.1 Principle ...................................................................................................... 30 2.2.4.2 Advantages ................................................................................................. 32 2.2.4.3 Application ................................................................................................. 33 2.2.4.4 Diffusive and binding layers used in DGT ................................................. 34 2.3 References .......................................................................................................................... 36 3 Aims and objectives ................................................................................................................... 49 4 Materials and methods .............................................................................................................. 50 4.1 Chemicals and materials .................................................................................................... 50 4.2 Methods .............................................................................................................................. 51 4.2.1 Cysteine modified silica preparation and characterisation .................................... 51 4.2.1.1 Modification of silica .................................................................................. 51 4.2.1.2 Characterisation of the modified silica ....................................................... 53 4.2.2 Diffusive gradients in thin films (DGT) technique ................................................ 54 4.2.2.1 DGT preparation and assembly .................................................................. 54 4.2.2.2 Basic DGT tests .......................................................................................... 55 4.2.3 Sample preparation of foodstuffs ..........................................................................