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Biomedical subjects

Hartmut Frank

Publications and source records attributed to Hartmut Frank.

8 recordsLinked to original sources
PubMed2006

Determination of some heavy metal cations in molten snow by transient isotachophoresis/ capillary zone electrophoresis.

Online combination of transient ITP and CZE is employed for the determination of Cd(II), Pb(II), Cu(II), Ni(II), and Zn(II). Acetic acid is used for creating the transient isotachophoretic state. alpha-Hydroxyisobutyric acid and 4-aminopyridine are used as BGEs for the separation and indirect UV detection. At optimum conditions, the method allows to determine the metals at levels of 40-120 microg/L, about 50 times more sensitive than conventional CZE. In combination with a 20-fold evaporative concentration, the method is suitable for environmental monitoring of the heavy metals in snow samples.

Cations↗
PubMed2006

Quantitative determination of perfluorinated surfactants in water by LC-ESI-MS/MS.

The surfactants perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), and derivatives of the latter have emerged as globally distributed persistent environmental contaminants. Methods for their reliable quantitative determination at ppt-levels (ng/L) are needed in order to detect their main sources, to elucidate their environmental fate, and to identify potential sinks. The common method for water analysis involves preconcentration by SPE followed by LC coupled to ESI MS/MS (LC-ESI-MS/ MS). All sample preparation steps must be carefully optimized in order to arrive at reliable quantitative data. Two major aspects are important: (i) during SPE, contaminations may arise from materials containing traces of PFOA/S; (ii) during LC-ESI-MS/ MS, ionization yields are suppressed by matrix components and depend upon the analyte concentrations in the extracts. The levels of PFOA/S in the river Roter Main near Bayreuth have been determined using the optimized method.

Alkanesulfonic Acids↗
PubMed2005

Polypyrrole-coated capillaries for capillary zone electrophoresis.

Fused-silica capillaries are permanently coated by silanization with 3-{[3-(N-pyrrole)-2-hydroxypropyl]amino}propyltriethoxysilane followed by oxidative polymerization of the pyrrole moieties with iron (III) or peroxodisulfate in the presence of chloride, perchlorate, or dextransulfate as anions. This approach allows to modulate the EOF in its magnitude as well as in its direction. With the small anions chloride and perchlorate, the EOF is reversed below pH 5 while with the large dextransulfate polyanions (DS) the EOF is relatively constant over the pH range from 2.5 to 9.4. This can be of advantage at low pH, at which the EOF of uncoated capillaries is close to zero. Application for separation of some herbicides is shown. The lifetime of PP-modified capillaries is satisfactory: the decrease in EOF is less than 3% during 80 analyses (160 min) and less than 5% over three months of storage. The reproducibility of capillary modification is about 5% (RSD of EOF).

Electrophoresis, Capillary↗
PubMed2005

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Editorial↗
PubMed2003

Determination of chloroacetates in atmospheric particulate matter.

Chloroacetates (CAAs) are ubiquitous in the environment. This study presents chloroacetates level in atmospheric particulate matter (APM) collected at Athens center. CAAs have been derivatized to their respective propyl esters and determined by gas chromatography (GC) with electron capture detection (ECD). Monochloroacetate (MCA) was the most abundant, followed by dichloroacetate (DCA) and trichloroacetate (TCA). Concentration values range from 3.0 to 8240 ng g(-1) (0.6-2010 pg m(-3)). Correlations to meteorological and pollution parameters are discussed, indicating that car exhausts may be a direct or indirect source of MCA, but origin from natural marine sources may also be relevant.

Acetates↗
PubMed2002

Trifluoroacetate in ocean waters.

Trifluoroacetate (TFA) is a ubiquitous xenochemical presently increasing in concentration in some environmental compartments, especially in the plant biomass of industrialized countries. Direct anthropogenic emissions of TFA are probably low, and the major anthropogenic sources are most likely various TFA precursors. As TFA has been found in ocean waters from remote locations, the question arose whether it is also a naturally occurring environmental chemical. Determination of the depth dependence of TFA in the ocean water column should shed some light on this question. However, in environmental analytical studies, the risk of systematic errors can be high and may lead to wrong conclusions. Therefore, special attention has been paid to the fact that TFA is a common atmospheric pollutant in the urban environment and that contributions from sampling, storage, and transport potentially lead to artificially high TFA values. The results of the ocean water sampling campaigns indicate that TFA is a naturally occurring chemical, homogeneously distributed in ocean waters of all ages with a concentration of about 200 ng/L.

Cities↗