On-line coupling Dotaz Zobrazit nápovědu
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.
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 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
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
Cílem práce bylo otestovat vhodné podmínky pro stanovení VPA v séru metodou ITP-CZE s vodivostní detekcí. Zjišťovalo se, zda pro metodu popsanou Ölveckou et al. se dá použít podobná příprava vzorku jako pro metodu plynové chromatografie, která se rutinně používá pro stanovení VPA v séru. 200 rl vzorku séra se extrahovalo 200 rl acetonu a po centrifugaci se odebralo 200 rl horní vrstvy a doplnilo do 10 ml demineralizovanou vodou. Spotřeba séra se při dávkování mikrostříkačkou dá snížit až na 5 l, což je výhodné hlavně pro terapeutické monitorování léků u dětí. Délka analýzy byla 20 minut. Metoda byla lineární v rozmezí 20–400 mg/l, což zahrnuje terapeutické rozmezí VPA (50 až 100 mg/l). Limit detekce a kvantifikace byl 2,5 a 8,5 mg/l. Variační koeficienty byly pod 10 % u všech tří koncentrací (30, 70 a 120 mg/l). Nová metoda byla porovnána s metodou plynové chromatografie pomocí regresní analýzy Passing-Bablok a zjistilo se, že obě metody dávají shodné výsledky.
The paper aimed to test suitable conditions for the determination of VPA in serum using the ITPCZE method with conductometric detection. It attempted to find whether for the method described by Ölvecká et al. it is possible to use a similar procedure of sample preparation as for the gas chromatographic method which is routinely employed for the assessment of VPA in serum. A 200 rl sample of serum was extracted with 200 rl of acetone and after centrifugation 200 rl of the upper layer was withdrawn and supplemented with demineralized water to make 10 ml. When a microsyringe is used for dosing, consumptions of serum can be reduced up to 5 rl, which is advantageous mainly for therapeutic drug monitoring in children. The length of analysis was 20 minutes. The method was linear within the range of 20–400 mg/l, which includes the therapeutic range of VPA (50–100 mg/l). The detection and quantification limits were 2.5 and 8.5 mg/l, respectively. The variation coefficients were below 10 % in all three concentrations (30, 70 and 120 mg/l). The new method was compared with the method of gas chromatography by means of the Passing-Bablok regression analysis and both methods were found to give identical results.
Společnost EULAR zahájila nový dvouletý kurz klinické revmatologie na internetu. Projekt zahrnuje 42 modulů věnovaných jednotlivým tematickým okruhům, které obsahují přehledné články, praktické kazuistiky a odkazy na literaturu se vztahem k tématu. Celý kurz je zakončen testem, na jehož základě je účastníkům vystaven certifikát EULAR. Autoři představují upravenou ukázkovou interaktivní kazuistiku, vybranou z modulu poly/dermatomyozitida. U 42leté nemocné s nebolestivou proximální svalovou slabostí byla na základě splnění kritérií Bohana a Petera diagnostikována idiopatická polymyozitida. Popis případu je doplněn otázkami zaměřenými na diagnosticko-terapeutický postup u nemocných s myopatiemi s komentovanými odpověďmi, které ilustrují obtíže spojené s péčí o tyto komplikované pacienty. Na závěr kazuistiky je čtenář seznámen s předpokládanou definitivní diagnózou nemocné.
EULAR commenced a new 2-years-course of clinical rheumatology on the internet. This project includes 42 modules dedicated to specific topics, which contain review articles, practical case reports and references related to the topic. The whole course will end with an examination, based on which the EULAR certificate will be granted to the participants. The authors present a modified sample interactive case report, chosen from the poly/dermatomyositis module. A 42-years old female patient with painless proximal muscle weakness was diagnosed with idiopathic polymyositis according to the Bohan and Peter criteria. The case description is coupled with questions directed on diagnostic-therapeutic practice in patients with myopathies, with commented answers, which illustrate the difficulties linked with the treatment of these complicated patients. In the end of this case report, the reader is acquainted with the definitive diagnosis of the patient.
- MeSH
- distanční studium metody trendy MeSH
- financování organizované MeSH
- internet trendy využití MeSH
- lidé MeSH
- polymyozitida diagnóza terapie MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- kazuistiky 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
