Hydrodynamic injection Dotaz Zobrazit nápovědu
An electrophoretic apparatus with a flow-gating interface has been developed, enabling hydrodynamic sequence injection of the sample into the separation capillary from the liquid flow by underpressure generated in the outlet electrophoretic vessel. The properties of the apparatus were tested on an artificial sample of an equimolar mixture of 100μM potassium and sodium ions and arginine. The repeatability of the injection of the tested ions expressed as RSD (in%) for the peak area, peak height and migration time was in the range 0.76-2.08, 0.18-0.68 and 0.28-0.48, respectively. Under optimum conditions, the apparatus was used for sequence monitoring of the reaction between the antidiabetic drug phenyl biguanide and the glycation agent methyl glyoxal. The reaction solution was continuously sampled by a microdialysis probe from a thermostated external vessel using a syringe pump at a flow rate of 3μLmin-1 and was injected into a separation capillary at certain time intervals. The electrophoretic separation progressed in a capillary with an internal diameter of 50μm with a length of 11.5cm and was monitored using a contactless conductivity detector.
- Klíčová slova
- Antidiabetic drug, Flow-gating interface, Hydrodynamic injection, Microdialysis, Sequence analysis, Short capillary separation,
- MeSH
- arginin MeSH
- biguanidy chemie MeSH
- časové faktory MeSH
- draslík MeSH
- elektroforéza kapilární přístrojové vybavení metody MeSH
- hydrodynamika * MeSH
- hypoglykemika chemie MeSH
- mikrodialýza MeSH
- pyruvaldehyd chemie MeSH
- roztoky MeSH
- sodík MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- arginin MeSH
- biguanidy MeSH
- draslík MeSH
- hypoglykemika MeSH
- phenyl biguanide MeSH Prohlížeč
- pyruvaldehyd MeSH
- roztoky MeSH
- sodík MeSH
A fast micellar electrokinetic chromatography (MEKC) method for simultaneous assay of aesculin, aesculetin, and phenylephrine was developed and validated. The separation was carried out in a fused-silica capillary (50 μm id, total length 64.5 cm, effective length 8.5 cm) with UV detection at 210 nm, temperature 25°C and separation voltage -25 kV. The samples were loaded hydrodynamically at a pressure of -50 mbar for 6 s. The background electrolyte of pH 8.6 contained 20 mM boric acid, 60 mM SDS, and 5% (v/v) of methanol. The calibration curves were linear in the range 10-500 μg/mL for aesculin and aesculetin and 12.5-625 μg/mL for phenylephrine. The RSD values of corrected peak areas were 0.6-1.2% (n = 6) when determining 0.2 mg/mL of aesculin and aesculetin and 0.25 mg/mL of phenylephrine in prepared standard mixtures. The method was successfully applied to the assay of aesculin and phenylephrine in a pharmaceutical preparation (RSD = 1.9-2.0%; n = 3) and the robustness of the method for both, the determination of analytes and the system suitability test parameter values, was evaluated with the use of Plackett-Burman design.
- Klíčová slova
- Aesculetin, Aesculin, Micellar electrokinetic chromatography, Phenylephrine, Short-end injection,
- Publikační typ
- časopisecké články MeSH
The relative amounts of DNA fragments in a mixture injected into the capillary by electromigration or hydrodynamically by pressure were compared. Even if the electrophoretic mobilities of DNA fragments with different sizes are the same in a free solution in the sample vial, the size bias is brought about by the different mobilities in a sieving medium and by the electroosmosis. The experiments were performed in capillaries filled with a solution of liquified agarose, a replaceable sieving medium. The experimental results were compared with a theoretical model.
- MeSH
- bakteriofág phi X 174 chemie MeSH
- DNA virů chemie MeSH
- DNA chemie MeSH
- elektrochemie MeSH
- elektroforéza v agarovém gelu MeSH
- teoretické modely MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- DNA virů MeSH
- DNA MeSH
Aim of the present paper was to study the electrochemical behavior of copper(II) induced complexes in extracts obtained from mycorrhizal and non-mycorrhizal maize (Zea mays L.) plants grown at two concentrations of copper(II): physiological (31.7 ng/mL) and toxic (317 μg/mL). Protein content was determined in the plant extracts and, after dilution to proper concentration, various concentrations of copper(II) ions (0, 100, 200 and 400 μg/mL) were added and incubated for 1h at 37°C. Further, the extracts were analyzed using flow injection analysis with electrochemical detection. The hydrodynamic voltammogram (HDV), which was obtained for each sample, indicated the complex creation. Steepness of measured dependencies was as follows: control 317 μg/mL of copper
Online electrokinetic preconcentration of magnetite core/carboxylic shell nanoparticles (MNPs) was studied by capillary electrophoresis using reversed and suppressed electroosmotic flow (EOF). 50mM sodium borate pH 9.5 was used as a background electrolyte. CTAB additive was used to reverse EOF and commercial polyvinylalcohol (PVA)-coated capillaries were used for EOF suppressed studies. Analyses in PVA-coated capillaries were more reproducible and therefore, the setup was further optimized in terms of water plug injection time, sample injection time, and voltage. Within the optimal conditions, the MNPs dispersed in water are electrokinetically loaded into BGE consisting of 50mM sodium borate pH 9.5 using -10kV for 120s. In comparison with the hydrodynamic injection of 5s by 50mbar, the electrokinetic injection allows 860-fold preconcentration of MNPs.
- Klíčová slova
- Capillary electrophoresis, Electrokinetic injection, Nanoparticles, On-line preconcentration, Stacking,
- MeSH
- elektroforéza kapilární přístrojové vybavení metody MeSH
- elektrolyty chemie MeSH
- elektroosmóza MeSH
- kyseliny karboxylové chemie MeSH
- magnetické nanočástice chemie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- elektrolyty MeSH
- kyseliny karboxylové MeSH
- magnetické nanočástice MeSH
A simple sample clean-up device with planar supported liquid membrane (SLM) was developed and coupled on-line to capillary electrophoresis (CE) for direct injection of human body fluids. Donor and acceptor compartments of the device were filled with diluted body fluid and deionized water, respectively, and the two solutions were separated by a thin SLM. Analytes of interest were selectively transported from the donor solution through the SLM into the acceptor solution by diffusion whereas interfering matrix components were efficiently retained on the SLM. Equilibrium between the concentrations of analytes at the SLM was obtained typically in 5 min. Then a CE separation capillary was inserted into the acceptor compartment to firmly touch the SLM and the pretreated sample was hydrodynamically injected into the capillary. The analytical procedure was demonstrated by rapid pretreatment, on-line injection, and CE determination of selected amino acids in human serum and plasma samples. 1-Ethyl-2-nitrobenezene and bis(2-ethylhexyl) phosphate (15%, v/v) was used as the selective SLM for clean-up of the body fluids and 0.5M acetic acid was used as a background electrolyte solution for CE analysis of the pretreated amino acids. Concentrations of amino acids on acceptor side of the SLM reached 40-58% of their original concentrations in donor solution after 5 min equilibration time and then remained constant proving that equilibrium was achieved at the SLM. Injection of the pretreated samples was highly repeatable with RSD values of peak areas 2.4-8.4% and 3.4-10.5% for standard solutions and real samples, respectively. Limits of detection between 0.75 and 2.5 μM were achieved, corresponding to 3.75-12.5 μM in 1:4 diluted real samples, which ensure sensitive determination of most amino acids in the body fluids. The developed method is fast, simple, efficient, cheap and selective and may be applied to determination of a wide range of analytes in various samples with complex matrices.
- MeSH
- aminokyseliny krev MeSH
- biochemická analýza krve přístrojové vybavení metody MeSH
- design vybavení MeSH
- elektroforéza kapilární přístrojové vybavení metody MeSH
- lidé MeSH
- membrány umělé * MeSH
- reprodukovatelnost výsledků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- aminokyseliny MeSH
- membrány umělé * MeSH
We use analytical methods and particle-in-cell simulation to investigate the origin of electrons accelerated by the process of direct laser acceleration driven by high-power laser pulses in preformed narrow cylindrical plasma channels. The simulation shows that the majority of accelerated electrons are originally located along the interface between the channel wall and the channel interior. The analytical model based on the electron hydrodynamics illustrates the underlying physical mechanism of the release of electrons from the channel wall when irradiated by an intense laser, the subsequent electron dynamics, and the corresponding evolution of the channel density profile. The quantitative predictions of the total charge of released electrons and the average electron density inside the channel are validated by comparison with the simulation results.
- Publikační typ
- časopisecké články MeSH
A computer-controlled hydrodynamic sample introduction method has been proposed for short-capillary electrophoresis. In the method, the BGE flushes sample from the loop of a six-way sampling valve and is carried to the injection end of the capillary. A short pressure impulse is generated in the electrolyte stream at the time when the sample zone is at the capillary, leading to injection of the sample into the capillary. Then the electrolyte flow is stopped and the separation voltage is turned on. This way of sample introduction does not involve movement of the capillary and both of its ends remain constantly in the solution during both sample injection and separation. The amount of sample introduced to the capillary is controlled by the duration of the pressure pulse. The new sample introduction method was tested in the determination of ammonia, creatinine, uric acid, and hippuric acid in human urine. The determination was performed in a capillary with an overall length of 10.5 cm, in two BGEs with compositions 50 mM MES + 5 mM NaOH (pH 5.1) and 1 M acetic acid + 1.5 mM crown ether 18-crown-6 (pH 2.4). A dual contactless conductivity/UV spectrometric detector was used for the detection.
- Klíčová slova
- Creatinine, Human urine, Hydrodynamic sampling, Short capillary separation, Uric acid,
- MeSH
- amoniové sloučeniny moč MeSH
- analýza moči přístrojové vybavení metody MeSH
- design vybavení MeSH
- elektrická vodivost MeSH
- elektroforéza kapilární přístrojové vybavení metody MeSH
- kationty moč MeSH
- kreatinin moč MeSH
- lidé MeSH
- limita detekce MeSH
- lineární modely MeSH
- reprodukovatelnost výsledků MeSH
- spektrofotometrie ultrafialová MeSH
- tlak MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- amoniové sloučeniny MeSH
- kationty MeSH
- kreatinin MeSH
The establishment of an efficient reaction mixture represents a crucial part of capillary electrophoresis based on-line enzymatic assays. For ketamine N-demethylation to norketamine mediated by the cytochrome P450 3A4 enzyme, mixing of enzyme and reactants in the incubation buffer at physiological pH was studied by computer simulation. A dynamic electrophoretic simulator that encompasses Taylor-Aris diffusivity which accounts for dispersion due to the parabolic flow profile associated with pressure driven flow was utilized. The simulator in the diffusion mode was used to predict transverse diffusional reactant mixing occurring during hydrodynamic plug injection of configurations featuring four and seven plugs. The same simulator in the electrophoretic mode was applied to study electrophoretic reactant mixing caused by voltage application in absence of buffer flow. Resulting conclusions were experimentally verified with enantioselective analysis of norketamine in a background electrolyte at low pH. Furthermore, simulations visualize buffer changes that occur upon power application between incubation buffer and background electrolyte and have an influence on the reaction mixture.
- Klíčová slova
- Capillary electrophoresis, Diffusion, Electrophoretically mediated microanalysis, Enzyme reaction, Simulation, Taylor-Aris dispersion,
- MeSH
- cytochrom P-450 CYP3A metabolismus MeSH
- difuze MeSH
- elektroforéza kapilární * MeSH
- enzymatické testy metody MeSH
- hydrodynamika MeSH
- ketamin analogy a deriváty chemie metabolismus MeSH
- počítačová simulace * MeSH
- pufry MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- cytochrom P-450 CYP3A MeSH
- ketamin MeSH
- norketamine MeSH Prohlížeč
- pufry MeSH
Enhanced sensitivity for determination of basic drugs in body fluids was achieved by in-line coupling of extraction across supported liquid membrane (SLM) to large electrokinetic injection and transient isotachophoresis-capillary zone electrophoresis (tITP-CZE) in commercial CZE instrument. Twelve cm long tITP plug of 300mM ammonium acetate was formed in the separation capillary just before the electrokinetic injection of acceptor solution containing nortriptyline, haloperidol and loperamide extracted across the SLM. The tITP plug ensured efficient stacking and preconcentration of the injected basic drugs due to the tITP action of ammonium and the drugs were then separated by CZE using 5.2M acetic acid as background electrolyte. No interferences were observed from highly-abundant body fluid species (NaCl and human serum albumin) due to the excellent clean-up properties of SLMs and analytical sensitivity increased up to 340 times compared to SLM extractions coupled in-line to CZE with standard hydrodynamic injections. The SLM-tITP-CZE method was characterized by good repeatability (RSDs of peak areas below 7.8%), linearity over two orders of magnitude (r(2) better than 0.994) and limits of detection (defined as 3×S/N) between 3 and 45μg/L. Interfacing of SLM extractions to CZE instrumentation was achieved by low-cost, disposable micro-extraction devices, which can be routinely prepared in every analytical laboratory. These devices eliminated sample carry-over, minimized the need for manual sample handling and ensured fully automated determination (including extraction, injection, preconcentration and separation) of the three basic drugs in 20μL of untreated body fluids.
- Klíčová slova
- Capillary electrophoresis, Complex samples, In-line sample pretreatment, Supported liquid membranes, Transient isotachophoresis,
- MeSH
- chemické techniky analytické přístrojové vybavení metody MeSH
- elektroforéza kapilární * MeSH
- izotachoforéza * MeSH
- lidé MeSH
- membrány umělé MeSH
- tělesné tekutiny chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- membrány umělé MeSH
