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Recovery of the method for assessment of fatty acids
Gross, Michal ; Hrstka, Miroslav (referee) ; Vítová, Eva (advisor)
The objective of this bachelor thesis is to verify recovery yield used for determination of fatty acids based on gas chromatography with flame-ionization detection. In the theoretical part, fatty acids and lipids are characterized and extraction of lipidic fraction from food samples with its subsequent adjustments is suggested. Furthermore, the principle and current instrumentation of capillary gas chromatography with flame-ionization detection and standard parameters for validation of the analytical method are specified. In the experimental part, verification of recovery yield of the method for assessment of fatty acids was performed. The used method includes extraction of lipids from a sample in accordance with the standard ISO 1735 regulation and transesterification of both free and bounded fatty acids catalysed by boron trifluoride according to the ISO 12966-2 standard regulation. The produced methyl esters can be effectively determined using gas chromatography with flame-ionization detector. Analysed samples of rapeseed oil and tilsiter-type cheese were purchased in a common food market.
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Assessment of fatty acids in processed cheese
Pruknerová, Kateřina ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This thesis is focused on determination of fatty acids in processed and/or processed cheese analogues using gas chromatography with FID detection. Characterization of fatty acids, various methods for lipid extraction and the possibilities of determination of fatty acids are described in the theoretical part. Simple and rapid method for the determination of fatty acids in natural and/or processed cheese was optimized and validated in the experimental part. The modified Folch method (by mixture of chloroform - methanol) was selected for lipid extraction from the samples. The standard method (ISO 5509), using a methanol solution of potassium hydroxide, was selected for lipid esterification. Type of the stationary phase and parameters of the column, flow of carrier gas, temperature of the injector, injection technique, temperature of the detector and temperature program were optimized. Calibration curves were constructed from five calibration points (in the concentration range of 0.01 - 60 g.ml-1), all correlation coefficients R2 were higher than 0,99. The limits of detection and quantification of individual fatty acids ranged from 0.002 - 6 g.ml-1. The repeatability of the method was good, all the relative standard deviations of the peaks were below 9 %. The optimized and validated method was applied to selected samples of processed cheese analogues. In total five types of analogues containing different kinds of fat (butter, apricot, linseed, black currant and grape seed oils) were analyzed. In samples 34 fatty acids were identified based on a comparison of retention times of standards.
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Analysis of hydroxy fatty acids using GC-EI-MS and HPLC-ESI-MS
GRAHAMMER, Johannes
The analysis of three different Hydroxyeicosatetraenoic acid in human blood plasma shall be determined using gas chromatography with electron ionization and high pressure liquid chromatogtaphy with electron spray ionization. The results shall be compared in terms of sensitivity, linearity and simplicity. Additionally the extraction of the lipids via protein precipitation shall be optimized.
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Recovery of the method for assessment of fatty acids
Gross, Michal ; Hrstka, Miroslav (referee) ; Vítová, Eva (advisor)
The objective of this bachelor thesis is to verify recovery yield used for determination of fatty acids based on gas chromatography with flame-ionization detection. In the theoretical part, fatty acids and lipids are characterized and extraction of lipidic fraction from food samples with its subsequent adjustments is suggested. Furthermore, the principle and current instrumentation of capillary gas chromatography with flame-ionization detection and standard parameters for validation of the analytical method are specified. In the experimental part, verification of recovery yield of the method for assessment of fatty acids was performed. The used method includes extraction of lipids from a sample in accordance with the standard ISO 1735 regulation and transesterification of both free and bounded fatty acids catalysed by boron trifluoride according to the ISO 12966-2 standard regulation. The produced methyl esters can be effectively determined using gas chromatography with flame-ionization detector. Analysed samples of rapeseed oil and tilsiter-type cheese were purchased in a common food market.
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Assessment of fatty acids in processed cheese
Pruknerová, Kateřina ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This thesis is focused on determination of fatty acids in processed and/or processed cheese analogues using gas chromatography with FID detection. Characterization of fatty acids, various methods for lipid extraction and the possibilities of determination of fatty acids are described in the theoretical part. Simple and rapid method for the determination of fatty acids in natural and/or processed cheese was optimized and validated in the experimental part. The modified Folch method (by mixture of chloroform - methanol) was selected for lipid extraction from the samples. The standard method (ISO 5509), using a methanol solution of potassium hydroxide, was selected for lipid esterification. Type of the stationary phase and parameters of the column, flow of carrier gas, temperature of the injector, injection technique, temperature of the detector and temperature program were optimized. Calibration curves were constructed from five calibration points (in the concentration range of 0.01 - 60 g.ml-1), all correlation coefficients R2 were higher than 0,99. The limits of detection and quantification of individual fatty acids ranged from 0.002 - 6 g.ml-1. The repeatability of the method was good, all the relative standard deviations of the peaks were below 9 %. The optimized and validated method was applied to selected samples of processed cheese analogues. In total five types of analogues containing different kinds of fat (butter, apricot, linseed, black currant and grape seed oils) were analyzed. In samples 34 fatty acids were identified based on a comparison of retention times of standards.
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