Liquid chromatography methods for analysis of microbial secondary metabolites of bioactive nature

(EN) This work is focused on development of new analytical methods involving modern solid phase extraction (SPE) for sample purification and pre-concentration, state-of-art ultra high- performance liquid chromatography (UHPLC) for separation of analytes and detection using diode-array detection (DAD) and/or time-of-flight mass spectrometry (ToFMS). The major part of the results has been published in prestigious international journals. The relevant yet unpublished results are included in the thesis as well. Besides a model comparison of various column chemistries used for "ultra-high performance" separations, some meaningful applications were developed. While one part of applications deal with determination of antibiotics as environmental contaminants that are responsible for the development and spread of microbial resistance, the second part is concerned with analyzing and finding of potential natural source of novel antimicrobial agents that can be further used as new antibiotics. The first part of the thesis was focused on the determination of residual antibiotics in different matrices (liquid hog manure, wastewater, surface water). The mostly prescribed antibiotics in both human and veterinary medicine were chosen as analytes in this study employing analytical methods consisting of UHPLC-DAD and..