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USD 60 /hr

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Hire Dr. Žiga T.

Slovenia

USD 60 /hr

LC/GC-MS Method Development Expert | Non-targeted & Metabolomics Data Analysis | Scientific Consultant

Profile Summary

I am an analytical chemist with expertise in chromatography coupled with mass spectrometry (LC-MS and GC-MS). I specialize in method development, including targeted quantification and non-targeted screening in environmental and metabolomics applications, as well as metabolomics-based data workflows that ensure high data quality, reproducibility, and biological interpretability. My work focuses on helping research teams and biotech groups develop and optimize analytical methods, improve data quality, and produce reproducible and publishable high-impact results. Key areas of expertise: LC-MS / GC-MS method development, optimization and validation Environmental and biological sample cleanup strategies (LLE, SPE, protein precipitation, etc.) Development of targeted quantification strategies Processing of high-resolution mass spectrometry data Development of QA/QC procedures and troubleshooting Creation of standard operating procedure (SOP) documentation for analytical workflows and QA/QC protocols Scientific writing, editing, and proofreading I collaborate with academic teams, research groups, and startups on a project basis to support method development, data processing, and documentation within the LC/GC-MS workflow. My goal is to provide practical, detail-oriented support that complements in-house expertise and helps streamline analytical tasks. If you're working on a challenging method, setting up a new workflow, or refining your data processing pipeline, I offer precise, science-driven support based on hands-on experience.

Subject Matter Expertise

• ★ Analytical Chemistry
• ☆ Separation & Purification
• ☆ Mass Spectrometry
• ☆ Liquid Chromatography/HPLC
• ☆ Gas Chromatography
• ☆ Molecular Biology
• ☆ Biomarkers
• ☆ Omics
• ☆ Metabolomics

Services

• Writing
• Research
• Consulting
• Data & AI
• Product Development

Writing Technical Writing, General Proofreading & Editing

Research Fact Checking, Scientific and Technical Research, Systematic Literature Review

Consulting Scientific and Technical Consulting

Data & AI Statistical Analysis, Data Mining

Product Development Concept Development

Work Experience

Postdoc

RECETOX, Masaryk University, Brno, Czech Republic

August 2022 - June 2025

PhD Fellow

Department of Environmental Science, Jožef Stefan Institute, Ljubljana, Slovenia

September 2017 - July 2022

Education

PhD (Ecotechnologies)

International Postgraduate School Jožef Stefan, Ljubljana, Slovenia

September 2017 - July 2022

MS Chemistry

Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia

October 2014 - September 2017

BSc Chemistry

Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia

October 2011 - September 2014

Certifications

• Certification details not provided.

Publications

JOURNAL ARTICLE

Žiga Tkalec, Štěpán Koudelka, Jana Klánová, Elliott J. Price (2025). Dual LC column characterization for mass spectrometry-based small molecule profiling of human plasma and serum . Analytica Chimica Acta.

Žiga Tkalec, Sarah Lennon, Jade Chaker, Elliott J. Price, Juliane Hollender, Carolin Huber, Tobias Schulze, Lutz Ahrens, Frederic Béen, Nicolas Creusot, et al. (2024). Harmonized quality assurance/quality control provisions to assess completeness and robustness of MS1 data preprocessing for LC-HRMS-based suspect screening and non-targeted analysis . TrAC Trends in Analytical Chemistry.

Žiga Tkalec, Jean-Philippe Antignac, Nicole Bandow, Frederic M. Béen, Lidia Belova, Jos Bessems, Bruno Le Bizec, Werner Brack, German Cano-Sancho, Jade Chaker, et al. (2024). Innovative analytical methodologies for characterizing chemical exposure with a view to next-generation risk assessment . Environment International.

J. Snoj Tratnik, A.A. Runkel, P. Klemenčič, N. Palir, A. Stajnko, M. Jagodic Hudobivnik, A. Alilović, Z. Tkalec, T. Kosjek, D. Mazej, et al. (2023). P09-46: Preliminary results of the second National Human Biomonitoring program in Slovenia: bisphenols, parabens, PFAS, glyphosate and trace elements in children and adolescents . Toxicology Letters.

Žiga Tkalec, Agneta Annika Runkel, Tina Kosjek, Milena Horvat, Ester Heath (2023). Contaminants of emerging concern in urine: a review of analytical methods for determining diisocyanates, benzotriazoles, benzothiazoles, 4-methylbenzylidene camphor, isothiazolinones, fragrances, and non-phthalate plasticizers . Environmental Science and Pollution Research.

Schillemans, T., Iszatt, N., Remy, S., Schoeters, G., Fernández, M.F., D'Cruz, S.C., Desalegn, A., Haug, L.S., Lignell, S., Lindroos, A.K., et al.(2023). Cross-sectional associations between exposure to per- and polyfluoroalkyl substances and body mass index among European teenagers in the HBM4EU aligned studies . Environmental Pollution. 316.

Govarts, E., Gilles, L., Rodriguez Martin, L., Santonen, T., Apel, P., Alvito, P., Anastasi, E., Andersen, H.R., Andersson, A.-M., Andryskova, L., et al.(2023). Harmonized human biomonitoring in European children, teenagers and adults: EU-wide exposure data of 11 chemical substance groups from the HBM4EU Aligned Studies (2014–2021) . International Journal of Hygiene and Environmental Health. 249.

Žiga Tkalec, Garry Codling, Jana Klánová, Milena Horvat, Tina Kosjek (2022). LC-HRMS based method for suspect/non-targeted screening for biomarkers of chemical exposure in human urine . Chemosphere.

Tkalec, Codling, G., Klánová, J., Horvat, M., Kosjek, T.(2022). LC-HRMS based method for suspect/non-targeted screening for biomarkers of chemical exposure in human urine . Chemosphere. 300.

Runkel, A.A., Mazej, D., Snoj Tratnik, J., Tkalec, Ž., Kosjek, T., Horvat, M.(2022). Exposure of men and lactating women to environmental phenols, phthalates, and DINCH . Chemosphere. 286.

Tkalec, Ž., Codling, G., Tratnik, J.S., Mazej, D., Klánová, J., Horvat, M., Kosjek, T.(2022). Suspect and non-targeted screening-based human biomonitoring identified 74 biomarkers of exposure in urine of Slovenian children . Environmental Pollution. 313.

Tkalec, Ž., Negreira, N., López de Alda, M., Barceló, D., Kosjek, T.(2022). UHPLC-HRMS data from non-targeted screening for biotransformation products of cytostatic drug imatinib . Data in Brief. 41.

Žiga Tkalec, Tina Kosjek, Janja Snoj Tratnik, Anja Stajnko, Agneta Annika Runkel, Marianthi Sykiotou, Darja Mazej, Milena Horvat(2021). Exposure of Slovenian children and adolescents to bisphenols, parabens and triclosan: Urinary levels, exposure patterns, determinants of exposure and susceptibility . Environment International. 146. p. 106172. Elsevier {BV}

Tkalec, Ž., Kosjek, T., Snoj Tratnik, J., Stajnko, A., Runkel, A.A., Sykiotou, M., Mazej, D., Horvat, M.(2021). Exposure of Slovenian children and adolescents to bisphenols, parabens and triclosan: Urinary levels, exposure patterns, determinants of exposure and susceptibility . Environment International. 146.

Tkalec, Negreira, N., López de Alda, M., Barceló, D., Kosjek, T.(2021). A novel workflow utilizing open-source software tools in the environmental fate studies: The example of imatinib biotransformation . Science of the Total Environment. 797.