Direct detection and quantification of malondialdehyde vapour in humid air using selected ion flow tube mass spectrometry supported by gas chromatography/mass spectrometry

RATIONALE: It has been proposed that malondialdehyde (MDA) reflects free oxygen-radical lipid peroxidation and can be useful as a biomarker to track this process. For the analysis of MDA molecules in humid air by selected ion flow tube mass spectrometry (SIFT-MS), the rate coefficients and the ion product distributions for the reactions of the SIFT-MS reagent ions with volatile MDA in the presence of water vapour are required. METHODS: The SIFT technique has been used to determine the rate coefficients and ion product distributions for the reactions of H3O(+), NO(+) and O2 (+•) with gas-phase MDA. In support of the SIFT-MS analysis of MDA, solid-phase microextraction, SPME, coupled with gas chromatography/mass spectrometry, GC/MS, has been used to confirm the identification of MDA. RESULTS: The primary product ions have been identified for the reactions of H3O(+), NO(+) and O2 (+•) with MDA and the formation of their hydrates formed in humid samples is described. The following combinations of reagent and the analyte ions (given as m/z values) have been adopted for SIFT-MS analyses of MDA in the gas phase: H3O(+): 109; NO(+): 89, 102; O2 (+•): 72, 90, 108, 126. The detection and quantification of MDA released by a cell culture by SIFT-MS are demonstrated. CONCLUSIONS: This detailed study has provided the kinetics data required for the SIFT-MS analysis of MDA in humid air, including exhaled breath and the headspace of liquid-phase biogenic media. The detection and quantification by SIFT-MS of MDA released by a cell culture are demonstrated. Copyright © 2015 John Wiley & Sons, Ltd

Status of selected ion flow tube MS: accomplishments and challenges in breath analysis and other areas

This article reflects our observations of recent accomplishments made using selected ion flow tube MS (SIFT-MS). Only brief descriptions are given of SIFT-MS as an analytical method and of the recent extensions to the underpinning analytical ion chemistry required to realize more robust analyses. The challenge of breath analysis is given special attention because, when achieved, it renders analysis of other air media relatively straightforward. Brief overviews are given of recent SIFT-MS breath analyses by leading research groups, noting the desirability of detection and quantification of single volatile biomarkers rather than reliance on statistical analyses, if breath analysis is to be accepted into clinical practice. A 'strengths, weaknesses, opportunities and threats' analysis of SIFT-MS is made, which should help to increase its utility for trace gas analysis

Selected ion flow tube mass spectrometry analyses of stable isotopes in water: isotopic composition of H3O+ and H3O+(H2O)3 ions in exchange reactions with water vapor

AbstractA new method has been developed for the determination of the isotope abundance ratios of deuterium, D, and oxygen-18, 18O, in water vapor (and water) using selected ion flow tube mass spectrometry (SIFT-MS). H3O+ ions are injected into the helium carrier gas where they associate with the H2O and HDO molecules in a sample of water introduced into the carrier gas. The D and 18O contents of the product cluster ions H8DO4+ and H918OO3+ at m/e = 74 and 75, respectively, are determined by reference to the majority cluster ion H9O4+ at m/e = 73. Allowance is made for the contribution of the H817OO3+ ions to the m/z = 74 ions. Absolute isotopic ratios are measured within seconds without the need for precalibration of the SIFT-MS instrument, currently to an accuracy of better than 2%

Evaluation of peroxidative stress of cancer cells in vitro by real time quantification of volatile aldehydes in culture headspace

Rationale Peroxidation of lipids in cellular membranes results in the release of volatile organic compounds (VOCs), including saturated aldehydes. The real‐time quantification of trace VOCs produced by cancer cells during peroxidative stress presents a new challenge to non‐invasive clinical diagnostics, which as described here, we have met with some success. Methods A combination of selected ion flow tube mass spectrometry (SIFT‐MS), a technique that allows rapid, reliable quantification of VOCs in humid air and liquid headspace, and electrochemistry to generate reactive oxygen species (ROS) in vitro has been used. Thus, VOCs present in the headspace of CALU‐1 cancer cell line cultures exposed to ROS have been monitored and quantified in real time using SIFT‐MS. Results The CALU‐1 lung cancer cells were cultured in 3D collagen to mimic in vivo tissue. Real‐time SIFT‐MS analyses focused on the volatile aldehydes: propanal, butanal, pentanal, hexanal, heptanal and malondialdehyde (propanedial), that are expected to be products of cellular membrane peroxidation. All six aldehydes were identified in the culture headspace, each reaching peak concentrations during the time of exposure to ROS and eventually reducing as the reactants were depleted in the culture. Pentanal and hexanal were the most abundant, reaching concentrations of a few hundred parts‐per‐billion by volume, ppbv, in the culture headspace. Conclusions The results of these experiments demonstrate that peroxidation of cancer cells in vitro can be monitored and evaluated by direct real‐time analysis of the volatile aldehydes produced. The combination of adopted methodology potentially has value for the study of other types of VOCs that may be produced by cellular damage

Control of dividing attachment

Dělící stroj umí dělit vodiče a kabely na uživatelsky stanovenou délku při zadaném počtu kusů. Tyto stroje jsou obvykle vyrobeny na zakázku pro potřeby vyžádané konkrétní aplikaci, nejsou na českém trhu příliš rozšířené. Zařízení popisované v tomto projektu potřebuji pro zvýšení produktivity práce při přípravě teplovzdorných vodičů, které se používají při zapojování těles rezistorů.Automatic cutting machine can cut wires and cables to user-defined length at a specified number of pieces. These equipments are usually custom-made for needs of the requested application and they are not very spread out tools on the Czech market. This described device is specified for efficiency-rise in the production of heat-resistant cables. These prepared cables are used for internal connection of the resistors.

Email Filtering Administration in Roundcube

Cílem této práce je vytvořit zásuvný modul pro webmail Roundcube, který umožňuje správu filtrování příchozí pošty a automatické oznamování nepřítomnosti, přičemž pro samotné filtrování je využit nástroj Procmail. V práci je dále prozkoumán způsob generování těchto filtrů/oznamování nepřítomnosti a jejich ucelené prezentace uživateli v rámci Roundcube. Výsledkem práce je funkční zásuvný modul a popis zajímavých pasáží z jeho implementace.The aim of this work is to create a plug-in for the Roundcube webmail, which allows the management of filters for incoming mail and automatic absence notification, where the Procmail tool is used for the filtering itself. The work also examines how to generate these filters and report the absence and their comprehensive presentation to the user within the Roundcube. The result of the work is a functional plug-in module and a description of interesting passages from its implementation.