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The usage of the "Ethanol as internal standard" method for the SPME-GC/FID analysis of volatile compounds in alcoholic products
Zavoralová, Lucie ; Korban, Anton (advisor) ; Sobotníková, Jana (referee)
This bachelor thesis dealt with the optimization of a method for the determination of 10 volatile compounds occurring as minor components in alcoholic products. The quantification was performed by the internal standard method, comparing the results using 1-pentanol and ethanol as classical and proposed internal standards, respectively. In the case of ethanol usage, better repeatability and accuracy of the results were expected as this method does not require any sample pre-treatment. The optimized measurement method was monitored for both internal standards, while following these parameters - repeatability, recovery, linearity and limits of detection and quantification. It was found out that, as expected, the method of the proposed ethanol internal standard gives more accurate results for the analysis of real alcoholic beverage samples. However, it did not outperform the classical internal standard method in all parameters. That one gave better results for repeatability and linearity for the set of calibration solutions measured, despite the fact that each sample had to be pre-treated. It was also found that samples with a high ethanol or other volatile content were not suitable for SPME analysis, because the fibre then loses its ability to sorb these substances in the same proportions and...
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Optimization of nontargeted analysis of beer by gas chromatography with mass spectrometry
Růžičková, Hedvika ; Vrzal, Tomáš (advisor) ; Korban, Anton (referee)
A non-targeted analysis of beer samples was carried out using dispersive liquid-liquid microextraction (DLLME) and gas chromatography with mass spectrometric detection (GC-MS). The method was optimized in terms of the composition of the reaction mixture and the type of dispersing agent used. One sample of alcoholic beer was used for the optimization. The processed data showed that the optimal arrangement of DLLME for non-targeted analysis of beer is a reaction mixture consisting of 1 ml of the sample, 300 µl of the extraction agent (chloroform), and 700 µl of the dispersing agent (ethanol).
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Development and metrological evaluation of gas chromatographic methods for quality and safety control of alcoholic products
Korban, Anton ; Čabala, Radomír (advisor) ; Kubinec, Róbert (referee) ; Maier, Vítězslav (referee)
Dissertation is dealing with the development of methods of quality control of alcoholic products, particularly, with quantification of volatile congeners. Previously suggested "Ethanol as internal standard (IS)" method was compared with existing analytical methods of internal and external standardisation. After satisfactory results the method was validated in one laboratory and then an inter-laboratory study which included nine laboratories from four countries was conducted. It was shown that the method usage on GC-FID is beneficial due to the absence of necessity of internal standard compound addition into tested sample, and absence of tedious sample alcohol by volume (ABV) or density measurements. The algorithm of the method usage on GC-MS instruments was also suggested and developed. It was found out that MS detector sensitivity should be reduced in order to register ethanol signal successfully. For this aim it was suggested to employ less abundant 47 m/z ions during ethanol elution. These ions correspond to non-fragmented ethanol molecules containing one heavy isotope, mainly 13 C. According to the obtained results the suggested methodology allowed employing the "Ethanol as IS" method on GC-MS instruments with metrological properties better or similar as for the traditional IS method. The...
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