Solid-phase microextraction Dotaz Zobrazit nápovědu
Pomocí mikroextrakce do pevné fáze (SPME) a plynové chromatografie byly v souboru 137 mikrobiologicky positivních i negativních klinických exsudátů stanoveny profily těkavých karboxylových kyselin (VFA). Zatímco aerobní bakterie poskytovaly málo charakteristické profily s malým obsahem nižších kyselin nebo byly chromatograficky negativní, poskytovaly anaerobní bakterie profily s větším obsahem vyšších kyselin. Ve 20,4 % exsudátů umožnila tato metoda během 15 minut detekci mikrobů nenalezených kultivačním vyšetřením, pravděpodobně nesporolujících anaerobů. Jejich bližší charakterizace je touto metodou v důsledku nestandardních podmínek jejich růstu možná jen orientačně.
The volatile fatty acid (VFA) patterns were determined in 137 microbiologically positive and negative clinical exudates using solid phase microextraction (SPME) and gas chromatography. The aerobic bacteria yielded less distinctive patterns with small content of lower acids, whereas patterns of anaerobes contained larger amounts of higher acids. The method made it possible to detect within 15 minutes bacteria, probably non-sporulating anaerobes, in 20,4 % of exudates false-negative by cultivation. Only tentative characterisation of these bacteria was possible due to the poorly defined conditions of their growth.
- MeSH
- aerobní bakterie izolace a purifikace metabolismus MeSH
- anaerobní bakterie izolace a purifikace metabolismus MeSH
- chromatografie plynová využití MeSH
- exsudáty a transsudáty mikrobiologie MeSH
- finanční podpora výzkumu jako téma MeSH
- kyseliny karboxylové analýza MeSH
- lidé MeSH
- Check Tag
- lidé MeSH
247 s.
- Konspekt
- Patologie. Klinická medicína
- NLK Obory
- chemie, klinická chemie
A method employing the direct immersion solid-phase microextraction followed by GC-MS analysis is presented for the determination of essential oils components in herbal tea infusions, i.e. their direct content in the liquid phase. The extraction performances were compared using five different microextraction fibres. Significant parameters affecting sorption process such as sample amount, sorption and desorption time and temperature, stirring speed, pH adjustment and effect of ionic strength were optimised and discussed. By optimising the key parameters, a detection limits (LOD = S/N × 3) for ten target marker compounds were obtained in the range from 5.3 to 48.2 ng/mL with recoveries ranged between 93.03 and 100.50%. Intra-day and inter-day repeatability at three concentration levels were found to be 1.1-15.3 and 7.2-15.5% RSD, respectively. Finally, the optimised procedure enabling a rapid and simple analysis of essential oils was applied for the direct determination of these compounds in ten herbal tea infusions.
The presented study investigates the use of passive sampling, i.e. solid phase microextraction with polydimethylsiloxane fibers (PDMS-SPME), to assess the bioavailability of fiver neutral organic chemicals (phenanthrene, pyrene, lindane, p,p'-DDT, and PCB 153) spiked to natural and artificial soils after different aging times. Contaminant bioavailability was assessed by comparing PDMS concentrations with results from a 10 day bioaccumulation test with earthworms (Eisenia fetida). The hypotheses tested were (i) organic carbon (OC) normalization, which is commonly used to account for sorption and bioavailability of hydrophobic organic chemicals in soil risk assessment, has limitations due to differences in sorptive properties of OC and aging processes (i.e. sequestration and biodegradation) and (ii) PDMS-SPME provides a more reliable measure of soil contaminant bioavailability than OC normalized soil concentrations. The above stated hypotheses were confirmed since the results showed that: (i) the PDMS/soil organic carbon partition ratio (R) accounting for the role that OC plays in partitioning significantly differed between soils and aging times and (ii) the correlation with earthworm concentrations was better using porewater concentrations derived from PDMS concentrations than when organic normalized soil concentrations were used. Capsule: Sorption of organic compounds measured by SPME method and their bioavailability to earthworms cannot be reliably predicted using OC content.
- MeSH
- látky znečišťující půdu chemie metabolismus MeSH
- mikroextrakce na pevné fázi * MeSH
- monitorování životního prostředí MeSH
- Oligochaeta chemie metabolismus MeSH
- organické látky analýza metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
RSC chromatography monographs
655 s.
- Konspekt
- Patologie. Klinická medicína
- NLK Obory
- chemie, klinická chemie
Methods for the separation and determination of terpenes (mono- and sesqui-) and phenylpropanoids such as eugenol and methyleugenol from samples of allspice berries have been developed. Chromatographic analyses of isolated groups of compounds were carried out by means of gas chromatography coupled with mass spectrometry. A comparison of various types of solid-phase microextraction fibers was performed. The highest yields of terpenes were extracted by polydimethylsiloxane and divinylbenzene/Carboxen/polydimethylsiloxane fibers (almost the same for these two fibers), approximately twice as much as by Carbowax/divinylbenzene fiber. The highest amounts of monoterpenes were extracted by divinylbenzene/Carboxen/polydimethylsiloxane fiber, and the highest amounts of sesquiterpenes were extracted by polydimethylsiloxane fiber. Moreover, the effect of water addition on extraction yields as well as time and temperature of extraction were tested. Aroma profiles of extracts obtained by solid-phase microextraction and essential oil obtained by hydrodistillation of allspice berries were compared. The aroma profile of the divinylbenzene/Carboxen/polydimethylsiloxane fiber extract was similar to the aroma profile of essential oil. Particular characteristics of volatile allspice matters were presented. The linear retention indices for each compound were calculated.
- MeSH
- destilace MeSH
- dimethylpolysiloxany chemie MeSH
- mikroextrakce na pevné fázi metody MeSH
- monoterpeny chemie MeSH
- oleje prchavé MeSH
- Pimenta (rod) chemie MeSH
- plynová chromatografie s hmotnostně spektrometrickou detekcí metody MeSH
- polyethylenglykoly chemie MeSH
- seskviterpeny chemie MeSH
- teplota MeSH
- terpeny analýza chemie MeSH
- vinylové sloučeniny chemie MeSH
- voda chemie MeSH
- Publikační typ
- časopisecké články MeSH
Head-space solid phase microextration (SPME), followed by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGC-TOFMS), has been implemented for the analysis of honey volatiles, with emphasis on the optimal selection of SPME fibre and the first- and second-dimension GC capillaries. From seven SPME fibres investigated, a divinylbenzene/Carboxen/polydimethylsiloxane (DVB/CAR/PDMS) 50/30 microm fibre provided the best sorption capacity and the broadest range of volatiles extracted from the headspace of a mixed honey sample. A combination of DB-5ms x SUPELCOWAX 10 columns enabled the best resolution of sample components compared to the other two tested column configurations. Employing this powerful analytical strategy led to the identification of 164 volatile compounds present in a honey mixture during a 19-min GC run. Combination of this simple and inexpensive SPME-based sampling/concentration technique with the advanced separation/identification approach represented by GCxGC-TOFMS allows a rapid and comprehensive examination of the honey volatiles profile. In this way, the laboratory sample throughput can be increased significantly and, at the same time, the risk of erroneous identification, which cannot be avoided in one-dimensional GC separation, is minimised.
