extraction process
Dotaz
Zobrazit nápovědu
Optimized acceptor solutions, which eliminate electrolytically induced variations in their pH values, have been shown to improve electromembrane extraction (EME) performance. Acceptor solutions containing 500 mM formic acid (pH 1.97) ensured stable EME process for three basic drugs extracted at 50 V across 1-ethyl-2-nitrobenzene and constant extraction recoveries (66-89%) were achieved for 40-80 min EMEs. Back-extraction of analytes into donor solutions has been eliminated by application of optimized acceptor solutions, moreover, saturation of acceptor solutions with analytes had no additional effect on their back-extraction; the presence of up to 300-fold excess of analytes in optimized acceptor solutions led to slightly reduced but stable enrichment of analytes over the entire extraction time. Stable EME performance has been also achieved for extractions into 100mM HCl, note however, that seriously compromised performance of subsequent capillary electrophoretic analyses has been observed due to high conductivities of resulting acceptor solutions. Electrolytically produced H(+) and OH(-) ions have mostly remained in corresponding operating solutions, have determined their final pH values and have not been subjects of EME transfers across selective phase interfaces as was experimentally verified by pH measurements of anolytes and catholytes at various EME times.
- MeSH
- autologní transplantace MeSH
- biokompatibilní materiály terapeutické užití MeSH
- extrakce zubů MeSH
- hřeben a laloky MeSH
- implantace zubů MeSH
- lidé MeSH
- membrány umělé MeSH
- resorpce alveolární kosti MeSH
- transplantace heterologní MeSH
- transplantáty klasifikace využití MeSH
- zubní lůžko patologie MeSH
- Check Tag
- lidé MeSH
- MeSH
- experimentální nádory patofyziologie terapie MeSH
- krysa rodu rattus MeSH
- myši MeSH
- nádorová transformace buněk farmakoterapie účinky léků MeSH
- regenerace jater imunologie účinky léků MeSH
- rostlinné extrakty aplikace a dávkování terapeutické užití MeSH
- transplantace nádorů metody MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
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
Fundamental operational principle and instrumental set-up of electromembrane extraction (EME) suggest that electrolysis may play an important role in this recently developed micro-extraction technique. In the present study, the effect of electrolysis in EME is described comprehensively for the first time and it is demonstrated that electrolysis considerably influences EME performance. Micro-electromembrane extraction (μ-EME) across free liquid membrane formed by 1-pentanol was utilized for real-time monitoring of the electrolytically induced changes in composition of μ-EME solutions. These changes were visualized with a set of acid-base indicators. Changes in colours of their aqueous solutions revealed serious variations in their pH values, which occurred within seconds to minutes of the μ-EME process. Variations of up to eight pH units were observed for indicator solutions initially prepared in 1, 5 and 10mM hydrochloric acid. No or only negligible pH changes (less than 0.15 pH unit) were observed for indicator solutions prepared in 50 and 100mM acetic acid demonstrating that initial composition of the aqueous solutions was the crucial parameter. These results were also confirmed by theoretical calculations of maximum pH variations in the solutions, which were based on total electric charge transfers measured in the μ-EME systems, and by exact measurements of their pH values after μ-EMEs. Acceptor solutions that, in the current practice, consist predominantly of low concentrations of strong mineral acids or alkali hydroxides may thus not always ensure adequate EME performance, which was manifested by decrease in extraction recoveries of a basic drug papaverine. A suitable remedy to the observed effects is the application of acceptor solutions containing high concentrations of weak acids or bases. These solutions not only eliminate the decrease in recoveries but also serve well as matrices of extracted samples for subsequent analysis by capillary electrophoresis.
Chirurgická extrakce spermií je v současnosti poslední možností pro pacienty s azoospermií na dosažení geneticky vlastního potomstva. Rozvoj reprodukční medicíny přináší neplodným párům stále pravděpodobnější naději na dosažení těhotenství. Úkolem urologa či androloga v tomto procesu je vyšetřit a léčit neplodného muže a také zvolit optimální metodu extrakce, která přinese co největší šanci na získání kvalitních spermií s minimálními riziky pro pacienta.
Surgical sperm extraction is currently the only option for patients with azoospermia to achieve genetically own offspring. The development of reproductive medicine brings infertile couples a more likely chance of achieving pregnancy. The task of urologist and andrologist in this process is to examine and treat the infertile man and also to choose the optimal extraction method, which will bring the greatest chance of obtaining quality sperm with minimal risks for the patient.
- MeSH
- azoospermie * chirurgie etiologie klasifikace MeSH
- lidé MeSH
- odběr spermií * klasifikace MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
The extraction efficiencies of thirty types of fibers produced by meltblown, alternating current electrospinning, and meltblown-co-electrospinning technologies were tested as advanced sorbents for on-line solid-phase extraction in a high-performance liquid chromatography system have been tested and compared with a commercial C18 sorbent. The properties of each fiber, which were often depended on the production process, and their applicability were demonstrated with the extraction of the model analytes nitrophenols and chlorophenols from various matrices including river water and to purify complex matrix human serum and bovine serum albumin from macromolecular ballast. Polycaprolactone fibers outperformed other polymers and were selected for subsequent modifications including (i) incorporation of hybrid carbon nanoparticles, i.e., graphene, activated carbon, and carbon black into the polymer prior to fiber fabrication, and (ii) surface modification by dip coating with polyhydroxy modifiers including graphene oxide, tannin, dopamine, hesperidin, and heparin. These novel fibrous sorbents were comparable to commercial C18 sorbent and provided excellent analyte recoveries of 70-112% even from the protein-containing matrices.
- MeSH
- extrakce na pevné fázi metody MeSH
- látky znečišťující životní prostředí * MeSH
- lidé MeSH
- nanovlákna * chemie MeSH
- polymery chemie MeSH
- řeky chemie MeSH
- sladká voda MeSH
- voda MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
This paper describes determination of the deoxynivalenol and ergosterol in samples from different varieties of barley and, consequently, malt produced from this barley. In total, 20 samples of barley and 20 samples of barley malt were analyzed. The alkaline hydrolysis with consequent extraction into hexane was applied to obtain the ergosterol from cereals. Extraction to acetonitrile/water and subsequent solid-phase extraction (SPE) were used for deoxynivalenol. The determination of the samples was performed on high-performance liquid chromatography using UV detection (ergosterol) and mass spectrometric detection (deoxynivalenol). The influence of the malting process on the production of two compounds of interest was assessed from obtained results. Ergosterol concentration ranged 0.88-15.87 mg/kg in barley and 2.63-34.96 mg/kg in malt, where its content increased to 95% compared to samples before malting. The malting process was observed as having a significant effect on ergosterol concentration (P = 0.07). The maximum concentration of deoxynivalenol was found to be 641 microg/kg in barley and 499 microg/kg in malt. Its concentration was lower than the legislative limit for unprocessed cereals (1,250 microg/kg). The statistic effect of the malting process on deoxynivalenol production was not found. Linear correlation between ergosterol and deoxynivalenol content was found to be very low (barley R = 0.02, malt R = 0.01). The results revealed that it is not possible to consider the ergosterol content as the indicator of deoxynivalenol contamination of naturally molded samples.
