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A new method for double bond characterization in lipids by ultraviolet photodissociation mass spectrometry
Rumlová, Barbora ; Strmeň, T. ; Cvačka, Josef
Lipids are structurally diverse biomolecules with vital functions in biological systems. Some of these functions are closely associated with the specific location of the carbon-carbon double bond in the lipid acyl chains. The chain length and the number of unsaturated carbon-carbon bonds can be determined using conventional MS/MS-based structural elucidation methods employing low or higher energy collision-induced dissociation. However, these dissociation techniques do not provide more subtle structural details, for example, the position of unsaturated bonds. Another type of activation method – ultraviolet photodissociation can be used for this purpose. In this study, a new method for characterization of double bond location in lipids acyl chain was developed using 193 nm ultraviolet photodissociation implemented on Orbitrap Fusion Lumos mass spectrometer. This approach is based on the derivatization of the double bond with bis-(5-iodo-[2]pyridyl)-disulfide, subsequent specific cleavages provide a unique diagnostic pair bearing information about the double bond position.
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Development of miniaturized ion source for atmospheric pressure chemical ionization (HPLC/MS)
Rumlová, Barbora ; Cvačka, Josef (advisor) ; Jelínek, Ivan (referee)
ionization in which the main component is a heated glass microfluidic chip. The ion source was assembled from the mirocfluidic chip placed on a micromanipulator and a needle electrode creating a corona discharge. The optimization of geometric arrangement of these components towards to inner heated capillary of the mass spectrometer LCQ Fleet (Thermo) was based on the signal intensity of reserpine. The solution of reserpine with concentration 10 µg/ w y g g y g . Furthermore, the flow rate of the nebulizing gas was optimized. The signal intensity of protonated molecule was two orders of magnitude higher than the signal generated by the commercial ion source for APCI (Thermo) using the same mass flow rate of the analyte. High signal instability of the detected ions is the persisting problem of the miniaturized ion source. Key words: mass spectrometry, micro APCI, microfluidic chip
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Temperature-programed micro-HPLC analysis of fatty acid methyl esters with APCI-MS detection
Vrkoslav, Vladimír ; Rumlová, Barbora ; Cvačka, Josef
HPLC/APCI-MS analysis at microliters-per-minute flow rates was optimized for separation of fatty acid methyl esters (FAMEs). HPLC C18 column with an internal diameter of 0.3 mm and isocratic elution using 99.9 % acetonitrile and 0.1% formic acid were employed. Standard APCI ion source was suitable for detection of FAMEs at 10 μl/min flow rate with the detection limit of micrograms-per-milliliter. APCI-MS spectra with predominant [M + H]+ molecular adducts were observed. The main advantage of micro-flow measurements is the possibility of using a temperature gradient, which significantly reduces retention times of FAMEs with longer aliphatic chain. The significant reduction of solvent consumption is also an important economic and environmental advantage. The positions of double bonds in FAME chains were established using acetonitrile-related adducts and tandem mass spectrometry. The optimized method was applied for analysis of FAMEs in triacylglycerol fraction of black currant seeds oil.
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Liquid chromatography with mass-spectrometric detection based on a microfluidic chip
Rumlová, Barbora ; Cvačka, Josef (advisor) ; Jelínek, Ivan (referee)
This diploma thesis deals with hyphenation of liquid chromatography with mass spectrometric detection based on microfluidic chip. Firstly, a miniaturized ion source for atmospheric-pressure chemical ionization (APCI), and atmospheric-pressure photoionization (APPI) was constructed. The main component of this source was a glass microfluidic chip. Geometry and the working conditions of the chip were optimized. Since both ion sources work under the same conditions, possible advantages resulting from APCI/APPI combination were investigated. Furthermore, the performance characteristics of the sources were evaluated, and compared to the conventional high flow-rate sources. The best performing source, APCI, was then hyphenated with HPLC using low flow-rate. A method for separation of fatty acids methyl esters using Supelco 37 standard was developed. The separation conditions were as follows: C18 reversed stationary phase, and acetonitrile containing 0.1 % formic acids was used as the mobile phase. A temperature gradient was used in order to enhance the speed of the separation. The limits of detection and quantitation of for selected analytes using the chip micro-APCI were calculated, and compared to the ones obtained using a commercially available micro-APCI source. The method was used for separation of...
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Development of miniaturized ion source for atmospheric pressure chemical ionization (HPLC/MS)
Rumlová, Barbora ; Cvačka, Josef (advisor) ; Jelínek, Ivan (referee)
ionization in which the main component is a heated glass microfluidic chip. The ion source was assembled from the mirocfluidic chip placed on a micromanipulator and a needle electrode creating a corona discharge. The optimization of geometric arrangement of these components towards to inner heated capillary of the mass spectrometer LCQ Fleet (Thermo) was based on the signal intensity of reserpine. The solution of reserpine with concentration 10 µg/ w y g g y g . Furthermore, the flow rate of the nebulizing gas was optimized. The signal intensity of protonated molecule was two orders of magnitude higher than the signal generated by the commercial ion source for APCI (Thermo) using the same mass flow rate of the analyte. High signal instability of the detected ions is the persisting problem of the miniaturized ion source. Key words: mass spectrometry, micro APCI, microfluidic chip
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