The electrochemical behavior of the herbicide chloridazon, I (pyrazon), at different pH is described. The electrode reaction (one wave in acidic media and another in alkaline media), investigated using direct current and pulse voltammetry, controlled-potential coulometry, and HPLC-MS, is a combination of the electroreduction (two-electron in the first step) and a kinetic process as a result of which simple compounds (HCl, NH3) are released and, moreover, a five-membered pyrrole cycle is formed in strongly acid media. Products of the kinetic reaction are further reducible. The dissociation constant of I, pKa = 2.96, was found spectrophotometrically. Fast-scan differential pulse voltammetry (FSDPV) was used for determination of I; the detection limit was 2.7 x 10(-8) mol L(-1) (0.006 microg L(-1)) at pH 2.3. Chloridazon was determined in spiked drinking and river water.
- MeSH
- chemické znečištění vody analýza MeSH
- elektrochemie přístrojové vybavení metody MeSH
- elektrody MeSH
- herbicidy analýza chemie MeSH
- koncentrace vodíkových iontů MeSH
- oxidace-redukce MeSH
- pyridaziny analýza chemie MeSH
- rtuť MeSH
- sladká voda analýza MeSH
- zásobování vodou analýza MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- herbicidy MeSH
- pyrazon MeSH Prohlížeč
- pyridaziny MeSH
- rtuť MeSH
Infrared laser ablation (IR-LA) has been studied as a sample introduction technique for the analysis of sintered cobalt-cemented tungsten carbide materials by inductively coupled plasma atomic emission spectrometry (ICP-AES). Fractionation of cobalt was observed. Linearity of calibration plots was verified at least up to 15% Ti, 8% Ta, and 3% Nb. Above 1% (m/m) Ti, Ta, and Nb, the repeatability of results was better than 3% R.S.D. The relative uncertainty at the centroid of the calibration line was in the range from +/- 3% to +/- 4% for Ti, Ta, and Nb with internal standardization by tungsten and up to +/- 5% without internal standardization. The limits of detection were 0.004% Ti, 0.001% Ta, and 0.004% Nb. Elimination of the cemented hardmetal dissolution procedure is the main advantage of this method.
- Publikační typ
- časopisecké články MeSH
Both boron and zirconium are present in ceramic materials as major silica components and have to be determined for quality control in the ceramic industry. For boron determination, sintering with a mixture of Na2CO3 and ZnO is proposed for decomposition of samples. For zirconium determination, acid digestion using an HF-HClO4 mixture and subsequent fusion with NaKCO3 and H3BO3 is proposed as decomposition step. The AAS absorbance signal of these elements is suppressed by the fusion elements in the samples. Therefore, the calibration solutions for both B and Zr must contain an appropriate concentration of sodium, sodium-potassium, and boron salts. An AIF3 solution was used for signal enhancement and improving the linearity of the Zr calibration curve. The methods proposed are well suited for the determination of higher concentrations of both boron and zirconium in silicate samples.
- Publikační typ
- časopisecké články MeSH
This brief overview summarises the immunoassay-based results obtained in the course of two years of the European INCO-Copernicus project BIOTOOLS. The project is aimed at simplifying the procedures for detection of surface active compounds (SAC) using, among others, antibody-based methods, i.e., microtiter plate-based enzyme-linked immunosorbent assays (ELISA), polarisation fluoro immunoassays (PFIA), and enzyme flow injection immunoassays (FIIA). Thirty-three rabbits were immunised with five different sulphophenyl moieties and three p-hydroxyphenyl moieties conjugated to protein immunogens to produce analytical antibodies against linear alkylbenzene sulphonates (LAS) and nonylphenol (NP). Although most of the antibodies exhibited binding reaction in indirect ELISA, only a few showed the required assay sensitivity. The best antibodies for LAS exhibited a 50% binding inhibition at IC50 19.8 microg L(-1) in indirect ELISA. Similar inhibition was observed for direct ELISA using peroxidase tracers. Antibodies against NP allowed the establishment of an indirect assay operating in the mg L(-1) range. A rapid and simple protocol for the screening of NP and LAS using homogeneous PFIA is described. The assay time for 10 samples was 7 minutes, thus allowing fast detection of the selected SAC at the mg L(-1) level. A generic competitive FIIA system, using a protein G column for separation of free and antibody-bound beta-galactosidase (beta-Gal) tracer, was developed for the screening of LAS, NP, and nonylphenol decaethoxylate (NPEO10). The FIIA had a sample throughput (STP) of 5-10 samples per hour, with limits of detection (LOD) for LAS, NP, and NPEO10 of 19.5, 52, and 2.4 microg L(-1), respectively. The developed FIIAs were applied to spiked rain and surface water.
- MeSH
- imunoanalýza metody MeSH
- králíci MeSH
- lidé MeSH
- povrchově aktivní látky analýza MeSH
- zvířata MeSH
- Check Tag
- králíci MeSH
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- povrchově aktivní látky MeSH
The electrochemical behavior of the herbicide metribuzin (4-amino-6-tert-butyl-4,5-dihydro-3-methylthio-1,2,4-triazin-5-one) at mercury electrodes was studied in aqueous solutions by direct current (DC) and tast polarography, differential pulse (DPV) and cyclic voltammetry (CV), and controlled-potential coulometry. The electrolysis products were separated and identified by chromatographic techniques combined with mass spectrometric detection. The reduction process in acid media includes two irreversible steps. In the first four-electron step the N-NH2 and the 1,6-azomethine bonds are reduced. The second step leads to the formation of 5-tert-butyl-2,3,4,5-tetrahydroimidazol-4-one at the mercury-pool electrode. The first reduction step combined with adsorptive accumulation of the herbicide molecule at the mercury electrode surface was used for its determination by differential pulse adsorptive stripping voltammetry (DPAdSV). Calibration curves were linear in the range 1-30 microg L(-1) with a detection limit of 0.27 microg L(-1) (1 nmol L(-1)) under the conditions used (buffer pH 4.5, Eacc = -0.45 V relative to Ag/AgCl and tacc = 10 s). Preconcentration on solid-phase extraction columns (SPE-phenyl) was used for the determination of very small amounts of metribuzin in river water samples. Recovery was approximately 97%. The reproducibility of the analytical procedure including SPE treatment and DPV determination was expressed as relative standard deviations of 2.53 and 3.66% for 2 and 6 microg L(-1) metribuzin, respectively.
- MeSH
- elektrochemie metody MeSH
- elektrody MeSH
- herbicidy analýza MeSH
- hmotnostní spektrometrie metody MeSH
- koncentrace vodíkových iontů MeSH
- polarografie metody MeSH
- rtuť chemie MeSH
- triaziny analýza MeSH
- vysokoúčinná kapalinová chromatografie metody MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- herbicidy MeSH
- metribuzin MeSH Prohlížeč
- rtuť MeSH
- triaziny MeSH
Infrared laser ablation (IRLA) was studied as a sample-introduction technique for the analysis of steels by inductively coupled plasma atomic emission spectrometry (ICP-AES). A comparison of two IRLA-ICP-AES systems based on Q-switched nanosecond Nd: YAG lasers was performed. The beam of the LINA-Spark atomizer (LSA Sarl, Cully, Switzerland) based on the Surelite 1-20 laser (Continuum, USA) was moved along a circle. A Perkin-Elmer Optima 3000 DV ICP system was used both with lateral and axial viewing modes. A laboratory-made ablation system based on the Brilliant laser (Quantel) was coupled to a Jobin-Yvon 170 Ultrace ICP (lateral viewing, polychromator part employed). A sample was rotated along a circle during ablation. Linearity of calibration plots was verified at least up to 19% Cr and 12% Ni without internal standardization for both LA-ICP-AES systems. Other elements examined were Mo up to 3%, Mn up 1.5%, Si up to 1.7%, and Cu up to 0.15%. The reproducibility was in the range 5-1 %RSD for a mass percentage 0.5-20% of steel constituents. The relative uncertainty of the centroids of the calibration lines was in the range from +/- 4% to +/- 12% for Cr, Ni, Mn, Mo, and Si, and from +/- 8% to +/- 19% for Cu. The lowest determinable quantities were calculated for calibration dependencies. Performances of both the IR-LA-ICP-AES were comparable.
- Publikační typ
- časopisecké články MeSH
The capabilities of neutron and photon activation analysis (NAA and PAA, respectively) for low-level determination of silicon in biological materials have been examined. Sensitivities of a variety of modes of NAA and PAA with radiochemical separation have been evaluated. Results are presented for silicon in reference materials CSRM 12-2-03 Lucerne, Bowen's Kale, NIST SRM-1571 Orchard Leaves, and NIST SRM-1515 Apple Leaves. The results were obtained by employing the 29Si(n,p)29Al reaction with fast reactor neutrons and the radiochemical procedure developed for aluminium separation. Possibilities of further improvement of the silicon determination limit down to the microg g(-1) level by employing NAA and PAA with radiochemical separation are outlined.
- MeSH
- aktivační analýza metody MeSH
- fotony MeSH
- hliník izolace a purifikace MeSH
- izotopy MeSH
- játra chemie MeSH
- křemík analýza MeSH
- neutronová aktivační analýza MeSH
- prasata MeSH
- radiochemie metody MeSH
- radionuklidy MeSH
- referenční standardy MeSH
- rostliny chemie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- hliník MeSH
- izotopy MeSH
- křemík MeSH
- radionuklidy MeSH
Several sets of reference air filters were prepared as part of an IAEA evaluation of the performance of laboratories involved in air-pollution studies. Each set comprised three polycarbonate membrane filters, two of which were loaded with urban air particulate matter (APM) obtained in Vienna or Prague, and one unloaded filter. The filters were loaded by filtration of a suspension of the APM materials in water. The homogeneity both of bulk APM materials and of the loaded filters was evaluated and found suitable by determining several elements by instrumental neutron-activation analysis (INAA), proton-induced X-ray emission (PIXE), and micro-X-ray energy-dispersive fluorescence analysis (micro-EDXRF). After evaluation of the homogeneity, INAA, PIXE, EDXRF, atomic absorption spectrometry (AAS), inductively coupled plasma optical emission spectrometry (ICP-OES), and ICP mass spectrometry (ICP-MS) were used to characterize the filter materials and establish "target values" and their associated standard deviations for 15 elements. Problems encountered during the preparation of these unique, simulated air filters and the criteria for setting both the target values and standard deviations are presented.
- MeSH
- chemické techniky analytické přístrojové vybavení metody normy MeSH
- filtrace přístrojové vybavení MeSH
- kovy analýza MeSH
- laboratoře normy MeSH
- látky znečišťující vzduch analýza normy MeSH
- monitorování životního prostředí přístrojové vybavení metody normy MeSH
- referenční standardy * MeSH
- řízení kvality MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- kovy MeSH
- látky znečišťující vzduch MeSH
After installation and calibration of k0-assisted NAA in three Central European research institutes (AEKI-Budapest, NPI-Rez, and IJS, Ljubljana), its validation was established via the analysis of three BCR certified reference materials. The matrices of choice were: CRM 277 estuarine sediment, CRM 038 coal fly ash from pulverized coal, and CRM 101 spruce needles. For some elements, e.g. Zn, Cd, and Hg, the analyses were not only performed instrumentally (INAA), but also in the radiochemical mode (RNAA). The work was performed in the framework of a European Copernicus Project.
- MeSH
- geologické sedimenty chemie MeSH
- látky znečišťující životní prostředí analýza MeSH
- pevné částice MeSH
- popel uhelný MeSH
- referenční standardy MeSH
- reprodukovatelnost výsledků MeSH
- rostliny chemie MeSH
- těžké kovy analýza MeSH
- uhlík chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- validační studie MeSH
- Geografické názvy
- Česká republika MeSH
- Maďarsko MeSH
- Slovinsko MeSH
- Názvy látek
- látky znečišťující životní prostředí MeSH
- pevné částice MeSH
- popel uhelný MeSH
- těžké kovy MeSH
- uhlík MeSH
A fast and simple capillary electrophoretic method suitable for the determination of native alpha-, beta-, gamma-cyclodextrins, their randomly substituted tert-butyl derivatives (average degree of substitution 3.8-4.4), heptakis (2,6-di-O-methyl)- and heptakis (2,3,6-tri-O-methyl)-beta-cyclodextrin was developed. Naphthyl-2-sulfonic acid (2-NSA), 3-iodobenzoic acid (3-IBA) and (1S)-1-phenylethylamine (PHEA) were tested as selective complex forming and UV absorbing background electrolyte additives. The composition of optimized background electrolyte for the separation of uncharged cyclodextrins and their derivatives was: 15 mM 3-iodobenzoic acid titrated with tris[hydroxymethyl]aminomethane to pH 8.0, 5% (v/v) of acetonitrile. A complete resolution of mono-2-O-, mono-3-O- and mono-6-O-carboxymethyl-beta-cyclodextrin regioisomers was achieved in the optimized background electrolyte system: 40 mM PHEA titrated with 2-[N-morpholino]ethanesulfonic acid to pH 5.6. In addition to indirect UV detection a contactless conductometric detector was successfully utilized.
- MeSH
- cyklodextriny analýza chemie MeSH
- elektrická vodivost MeSH
- elektrochemie metody MeSH
- elektroforéza kapilární metody MeSH
- indikátory a reagencie MeSH
- spektrofotometrie ultrafialová metody MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- cyklodextriny MeSH
- indikátory a reagencie MeSH
