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MeSH: Analytic Sample Preparation Methods-instrumentation

11 záznamů v Medvik Filtry

Článek

Large volume preconcentration and determination of nanomolar concentrations of iron in seawater using a renewable cellulose 8-hydroquinoline sorbent microcolumn and universal approach of post-column eluate utilization in a Lab-on-Valve system

Horstkotte, Burkhard
Autor Horstkotte, Burkhard Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University in Prague, Czech Republic. Electronic address: Horstkob@faf.cuni.cz
Chocholouš, Petr
Autor Chocholouš, Petr Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University in Prague, Czech Republic
Solich, Petr
Autor Solich, Petr Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University in Prague, Czech Republic

Talanta. 2016 ; 150 (-) : 213-23. [pub] 20151218

ISSN 1873-3573
Medvik
Zdroj

We report on a Lab-On-Valve (LOV) configuration for analyte preconcentration from milliliter sample volumes using confluent mixing in the holding coil for in-line addition of loading buffer. The system was applied to the spectrophotometric determination of iron(II) in acidified seawater using 1,10-phenanthroline as color reagent. A cellulose-based chelating sorbent containing 8-hydroxyquinoline was used for the first time in LOV and excellent retention behavior and loading capacity were found. The flow system employs a syringe pump for handling all solutions (sorbent suspension, loading buffer, water, eluent, and color reagent) and a peristaltic pump for sample propulsion and includes a fit-for-purpose 14 cm long detection glass flow cell and a bubble trap for in-line carrier degasification. Advantage was taken of the LOV flow-through port to keep the eluted analytes for re-aspiration for subsequent chromogenic reaction. In effect, a universal analyzer configuration and preconcentration procedure was developed, which is combinable with other analytes, sorbents, and reagents. Among the studied parameters were the compositions, pH, volumes, and flow rates of loading buffer, eluent, and color reagent, as well as the microcolumn size, repeatability, and system stability. Reproducibility of 4.1% RSD over the entire working range, a LOD of down to 5 nmol L(-1), sampling frequency of 12h(-1), and linearity up to 1 µmol L(-1) for 3.3 mL of sample were obtained and applicability to real samples was demonstrated. It was proven that both Fe(III) and Fe(II) were retained and yielded similar recovery and sensitivity values. The method was applied to coastal seawater samples and spiking experiments yielded recovery values close to 100%.

MeSH
barva MeSH
celulosa chemie MeSH
chelátory chemie MeSH
extrakce na pevné fázi MeSH
fenantroliny chemie MeSH
koncentrace vodíkových iontů MeSH
limita detekce * MeSH
metody pro přípravu analytických vzorků přístrojové vybavení metody MeSH
mořská voda chemie MeSH
oxychinolin chemie MeSH
pufry MeSH
reprodukovatelnost výsledků MeSH
železo analýza chemie izolace a purifikace MeSH
Publikační typ
časopisecké články MeSH
práce podpořená grantem MeSH

Kniha

Drogy v dopravě

Blažejovský, Marek
Autor Autorita

Praha : Wolters Kluwer, 2015

Vydání první 185 stran : ilustrace, tabulky ; 21 cm

Monografie pojednává o problematice nelegálních návykových látek v silniční dopravě. Obliba užívání drog v populaci se logicky promítá i do situace v silniční dopravě v podobě zvýšeného počtu řidičů řídících vozidlo pod vlivem návykové látky a zvýšeného počtu nehod zaviněných těmito řidiči. Autor analyzuje situace při řešení tohoto problému policií a dalšími odpovědnými orgány a uvádí komplikace s eliminací tohoto celospolečenského negativního jevu.

Článek online

Elektrochemické stanovení nízkomolekulárních antioxidantů v séru
[Electrochemical determination of low-molecular-weight antioxidants in blood serum]

Chemické listy. 2014 ; 108 (1) : 64-69.

Chem. Listy
ISSN 0009-2770
Medvik
Zdroj

The aim of the study was to establish and optimize an electrochemical method for the assay of low-molecular-weight antioxidants (LMWA). We used square-wave vol¬tammetry (at 01.1 V) on screen-printed sensors with C working electrodes. Optimum parameters were: potential step and amplitude 5 mV and frequency 1 Hz. Ascorbic acid, trolox, N-acetylcysteine and melatonin were used as standard antioxidants to test the linearity and sensitivity of the method. Limits of detection were 0.09 mmol l1 for ascorbic acid, 0.04 mmol l1 for melatonin, 0.03 mmol l1 for trolox, and 0.07 mmol l1 for N-acetylcysteine. 20 ??????l samples were used. The suitability of the method for the assay was confirmed by the standard ferric reducing ability of plasma test. Both methods correlated well (correlation coefficient 0.9778).

Článek online

Preparative divergent flow IEF without carrier ampholytes for separation of complex biological samples

Electrophoresis. 2010 ; 31 (3) : 433-439.

ISSN 1522-2683
Medvik
Zdroj

Efficient separation method is a crucial part of the process in which components of highly complex biological sample are identified and characterized. Based on the principles of recently newly established electrophoretic method called divergent flow IEF (DF IEF), we have tested the DF IEF instrument which is able to operate without the use of background carrier ampholytes. We have verified that during separation and focusing of sample consisting of high numbers of proteins (yeast lysate and wheat flour extract), the pH gradient of preparative DF IEF can be created by autofocusing of the sample components themselves without any addition of carrier ampholytes. In DF IEF, the proteins are separated, desalted and concentrated in one step. The fractions of yeast lysate sample, collected at the DF IEF output and subjected to gel IEF, contained the zones of proteins gradually covering the pI values from 3.7 to 8.5. In our experimental arrangement, the highest number of proteins has been found in fractions with pI values around 5.3 as detected by polyacrylamide gel IEF with CBB staining. During DF IEF, the selected protein bands have been concentrated up to 16.8-fold.