In my work, I examined the effects of dilution of complex samples on chromatographic peak profiles. For the study, I used samples of Donat Mg mineral water and seawater, which differ in concentration range and cation ratios. For each sample, I prepared six differently diluted solutions and analyzed them by cation chromatography. The resulting chromatograms were appropriately processed, integrated, and used to derive results for peak areas, heights, and retention times. These data were then analyzed both computati-onally and visually (by plotting graphs using MS Excel). The results confirmed that dilu-tion has a significant effect on the peak areas, heights, and retention times of chromato-graphic peaks, which is directly related to the ionic strength of the sample and to in-teractions between ions within the chromatographic column. For both complex samples, increasing dilution led to a systematic decrease in signal intensity, while the retention times of most ions increased. An exception is the sodium ion, for which the retention time shortens upon dilution, likely due to column overloading and the influence of high concentrations of divalent ions. An ideal chromatographic peak has a Gaussian shape, is symmetrical, well separated from adjacent peaks, and exhibits a stable retention time. In this study, the occurrence of peak fronting was observed, which is characteristic of co-lumn overloading, as well as peak tailing resulting from the slow desorption of the analyte from the ion-exchange sites. As a consequence, overlapping of individual chro-matographic peaks is observed in the chromatograms, which complicates quantitative determination and may even hinder qualitative identification, as in the case of strontium ion. By comparing different integration methods available in the PeakNet software, it was determined that the tangential skim integration method was the most suitable for this study. Based on visual inspection of the chromatograms and statistical analysis of peak areas and heights (calculation of relative standard deviation for each ion), the most appropriate solutions for reliable determination of the composition of complex samples were identified for each sample. For Donat Mg mineral water, solution A3 with a dilu-tion factor of 60.73 was found to be optimal, while for seawater the optimal solution was A5 with a dilution factor of 23.80.
The results obtained in this master’s thesis open possibilities for further research. It wo-uld be reasonable to include additional complex samples with different ionic composi-tions in order to verify whether they confirm the conclusions drawn in this study.
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