On-line coupling
Dotaz
Zobrazit nápovědu
In this work, an on-line SPE-HPLC method with spectrophotometric detection was developed for the determination of coumarins in complex samples. For the on-line cleanup of samples, a molecularly imprinted polymer was packed into the column cartridge and coupled directly with HPLC (MISPE-HPLC) using a column switching system. The separation of coumarins was performed on a C18 core-shell column (100×4.6mm, 5μm) with a mobile phase consisting of 0.3% acetic acid/acetonitrile with gradient elution at a flow-rate of 1mLmin-1. The total time of the whole analytical run, including the extraction step, was 13.25min. The on-line MISPE-HPLC method was optimized and validated. The results showed good linearity (0.10-100μgmL-1) with correlation coefficients higher than 0.99. The LOD values were from 0.03 to 0.15μgmL-1. The proposed method was successfully applied for analysis of real samples (Cassia cinnamon, chamomile tea, and Tokaj specialty wines) and obtained recoveries varied from 78.7% to 112.2% with an RSD less than 9%.
The presented review provides comprehensive and detailed characteristics on microcolumn separation techniques off-line coupled to mass spectrometry. Major attention is paid to the classification of junctions between the separation column and the deposition needle and to the process by which the liquid is transferred onto the target. Both contact and non-contact deposition techniques are covered. In order to emphasize the significance of the topic of off-line separations, current commercially available devices have been compared in terms of their potential utilization in analytical chemistry with a summarization of applications used over the past few years.
The presented paper deals with a new methodology for direct determination of propranolol in human plasma. The methodology described is based on sequential injection analysis technique (SIA) coupled with solid phase extraction (SPE) column based on restricted access materials (RAM). Special RAM column containing 30 microm polymeric material-N-vinylacetamide copolymer was integrated into the sequential injection manifold. SIA-RAM system was used for selective retention of propranolol, while the plasma matrix components were eluted with two weak organic solutions to waste. Due to the acid-basic and polarity properties of propranolol molecule and principles of reversed-phase chromatography, it was possible to retain propranolol on the N-vinylacetamide copolymer sorbent (Shodex MSpak PK-2A 30 microm (2 mm x 10 mm)). Centrifuged plasma samples were aspirated into the system and loaded onto the column using acetonitrile-water (5:95, v/v), pH 11.00, adjusted by triethylamine. The analyte was retained on the column while proteins contained in the sample were removed to waste. Interfering endogenous substances complicating detection were washed out by acetonitrile-water (15:85), pH 11.00 in the next step. The extracted analyte was eluted by means of tetrahydrofuran-water (25:75), pH 11.00 to the fluorescence detector (emission filter 385 nm). The whole procedure comprising sample pre-treatment, analyte detection and column reconditioning took about 15 min. The recoveries of propranolol from undiluted plasma were in the range 96.2-97.8% for three concentration levels of analyte. The proposed SIA-RAM method has been applied for direct determination of propranolol in human plasma.
- MeSH
- financování organizované MeSH
- kalibrace MeSH
- koncentrace vodíkových iontů MeSH
- lidé MeSH
- molekulární struktura MeSH
- on-line systémy přístrojové vybavení MeSH
- propranolol chemie krev MeSH
- průtoková injekční analýza metody přístrojové vybavení MeSH
- senzitivita a specificita MeSH
- Check Tag
- lidé MeSH
In this work, the combination of an immobilized enzyme microreactor (IMER) based on the clinically important isoform cytochrome P450 2C9 (CYP2C9) with capillary electrophoresis (CE) is presented. The CYP2C9 was attached to magnetic SiMAG-carboxyl microparticles using the carbodiimide method. The formation of an IMER in the inlet part of the separation capillary was ensured by two permanent magnets fixed in a cassette from the CE apparatus in the repulsive arrangement. The resulting on-line system provides an integration of enzyme reaction mixing and incubation, reaction products separation, detection and quantification into a single fully automated procedure with the possibility of repetitive use of the enzyme and minuscule amounts of reactant consumption. The on-line kinetic and inhibition studies of CYP2C9's reaction with diclofenac as a model substrate and sulfaphenazole as a model inhibitor were conducted in order to demonstrate its practical applicability. Values of the apparent Michalis-Menten constant, apparent maximum reaction velocity, Hill coefficient, apparent inhibition constant and half-maximal inhibition concentration were determined on the basis of the calculation of the effective substrate and inhibitor concentrations inside the capillary IMER using a model described by the Hagen-Poisseulle law and a novel enhanced model that reflects the influence of the reactants' diffusion during the injection process.
- MeSH
- bioreaktory MeSH
- difuze MeSH
- diklofenak chemie MeSH
- elektroforéza kapilární * MeSH
- enzymy imobilizované metabolismus MeSH
- kinetika MeSH
- objevování léků přístrojové vybavení metody MeSH
- systém (enzymů) cytochromů P-450 chemie metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Open tubular capillary enzyme reactors were studied for rapid protein digestion and possible on-line integration into a CE/ESI/MS system. The need to minimize the time of the analyte molecules to diffuse towards the surface immobilized enzyme and to maximize the surface-to-volume (S/V) ratio of the open tubular reactors dictated the use of very narrow bore capillaries. Extremely small protein amounts (atto-femtomoles loaded) could be digested with enzymes immobilized directly on the inside wall of a 10 microm I.D. capillary. Covalently immobilized L-1-tosylamido-2-phenylethyl chloromethyl ketone (TPCK)-trypsin and pepsin A were tested for the surface immobilization. The enzymatic activity was characterized in the flow-through mode with on-line coupling to electrospray ionization-time of flight-mass spectrometer (ESI/TOF-MS) under a range of protein concentrations, buffer pH's, temperatures and reaction times. The optimized reactors were tested as the nanospray needles for fast identification of proteins using CE-ESI/TOF-MS.
- MeSH
- biokompatibilní potahované materiály MeSH
- elektroforéza kapilární metody MeSH
- elektroforéza mikročipová MeSH
- elektrolyty MeSH
- enzymy imobilizované chemická syntéza klasifikace MeSH
- financování organizované MeSH
- hmotnostní spektrometrie s elektrosprejovou ionizací metody MeSH
- mikrochemie MeSH
- on-line systémy MeSH
- pepsin A metabolismus MeSH
- proteiny analýza chemie MeSH
- sekvenční analýza proteinů metody MeSH
- senzitivita a specificita MeSH
- studie proveditelnosti MeSH
- trypsin metabolismus MeSH
A novel approach for automation of Micro-Extraction by Packed Sorbent (MEPS), a solid phase extraction technique, is presented, enabling precise and repeatable liquid handling due to the employment of sequential injection technique. The developed system was used for human urine sample clean-up and pre-concentration of betaxolol before its separation and determination. A commercial MEPS C-18 cartridge was integrated into an SIChrom™ system. The chromatographic separation was performed on a monolithic High Resolution C18 (50×4.6 mm) column which was coupled on-line in the system with Micro-Extraction using an additional selection valve. A mixture of acetonitrile and aqueous solution of 0.5% triethylamine with acetic acid, pH adjusted to 4.5 in ratio 30:70 was used as a mobile phase for elution of betaxolol from MEPS directly onto the monolithic column where the separation took place. Betaxolol was quantified by a fluorescence detector at wavelengths λ(ex)=220 nm and λ(em)=305 nm. The linear calibration range of 5-400 ng mL(-1), with limit of detection 1.5 ng mL(-1) and limit of quantification 5 ng mL(-1) and correlation r=0.9998 for both the standard and urine matrix calibration were achieved. The system recovery was 105±5%; 100±4%; 108±1% for three concentration levels of betaxolol in 10 times diluted urine - 5, 20 and 200 ng mL(-1), respectively.
- MeSH
- analýza moči přístrojové vybavení metody MeSH
- betaxolol izolace a purifikace moč MeSH
- chromatografie metody MeSH
- design vybavení MeSH
- fluorescenční spektrometrie MeSH
- injekce * MeSH
- lidé MeSH
- mikroextrakce na pevné fázi metody MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem 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
The review presents an evaluation of the development of on-line, at-line and in-line sample treatment coupled with capillary and microchip electrophoresis over the last 10 years. In the first part, it describes different types of flow-gating interfaces (FGI) such as cross-FGI, coaxial-FGI, sheet-flow-FGI, and air-assisted-FGI and their fabrication using molding into polydimethylsiloxane and commercially available fittings. The second part deals with the coupling of capillary and microchip electrophoresis with microdialysis, solid-phase, liquid-phase, and membrane based extraction techniques. It mainly focuses on modern techniques such as extraction across supported liquid membrane, electroextraction, single drop microextraction, head space microextraction, and microdialysis with high spatial and temporal resolution. Finally, the design of sequential electrophoretic analysers and fabrication of SPE microcartridges with monolithic and molecularly imprinted polymeric sorbents are discussed. Applications include the monitoring of metabolites, neurotransmitters, peptides and proteins in body fluids and tissues to study processes in living organisms, as well as the monitoring of nutrients, minerals and waste compounds in food, natural and wastewater.
- MeSH
- elektroforéza kapilární metody MeSH
- elektroforéza mikročipová * metody MeSH
- mikrodialýza MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
