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Biomedical subjects

P Popp

Publications and source records attributed to P Popp.

32 records · Page 2Linked to original sources
PubMed2000

Evaluation of extraction procedures for the ion chromatographic determination of arsenic species in plant materials.

The determination of arsenic species in plants grown on contaminated sediments and soils is important in order to understand the uptake, transfer and accumulation processes of arsenic. For the separation and detection of arsenic species, hyphenated techniques can be applied successfully in many cases. A lack of investigations exists in the handling (e.g., sampling, pre-treatment and extraction) of redox- and chemically labile arsenic species prior to analysis. This paper presents an application of pressurized liquid extraction (PLE) using water as the solvent for the effective extraction of arsenic species from freshly harvested plants. The method was optimized with respect to extraction time, number of extraction steps and temperature. The thermal stability of the inorganic and organic arsenic species under PLE conditions (60-180 degrees C) was tested. The adaptation of the proposed extraction method to freeze-dried, fine-grained material was limited because of the insufficient reproducibility in some cases.

Arsenic↗
PubMed2000

Solid-phase microextraction-gas chromatography-mass spectrometry of biologically active substances in water samples.

A solid-phase microextraction (SPME) method for determining trace amounts of polar, biologically active substances in water systems was developed and compared with solid-phase extraction followed by derivatization and GC-MS. SPME was examined with respect to the simultaneous determination of pharmaceuticals such as ibuprofen, paracetamol, phenazone, carbamazepine, and nonylphenols known to be xenoestrogens. The extraction performance of different SPME fibre coatings was studied. Coatings like polyacrylate and Carbowax-divinylbenzene proved to be the best suited. The optimum extraction time was found to be 30 min and the detection limits were between 0.2 and 50 microg/l. Low concentrations of accompanying organic matter did not impair these limits. One of the main pharmaceutical contaminants found in ground and river water around Leipzig (Germany) was ibuprofen, with a concentration in the ng/l range. The enantioselective metabolism of ibuprofen was investigated.

Estrogens↗
PubMed2000

Determination of chlorophenols in soils using accelerated solvent extraction combined with solid-phase microextraction.

A method for the determination of chlorophenols in soil samples using accelerated solvent extraction (ASE) with water as the solvent combined with solid-phase microextraction (SPME) and GC/MS has been developed. Important ASE parameters, such as extraction temperature and time, were optimized using a spiked wetland soil. The effect of small amounts of organic modifiers on the extraction yields was studied. An extraction temperature of 125 degrees C and 10 min extractions performed three times proved optimal. Two ASE-SPME procedures without and with an organic modifier (5% acetonitrile) were evaluated with respect to precision and detection limits (LOD). The reproducibility of replicate water extractions/SPME determinations (n = 6) was in the range 7-20% relative standard deviation for the nine chlorophenols investigated. LOD values in the low-ppb range were achieved for all chlorophenols. The ASE-SPME procedure presented here was applied to the determination of chlorophenols in soil samples taken from contaminated areas near Bitterfeld, Germany.

Chlorophenols↗
PubMed2000

Chlorobenzenes and hexachlorocyclohexanes (HCHs) in the atmosphere of Bitterfeld and Leipzig (Germany).

Concentrations of tetrachlorobenzenes, pentachlorobenzene, hexachlorobenzene and alpha-, beta-, gamma- and delta-HCH in air and deposition were measured at three different contaminated sites in Greppin, Roitzsch (both near Bitterfeld) and Leipzig during five time intervals of 14 days in the summer months of 1998. The mean values of the chlorobenzene concentrations (gas phase and particle bound portions) over the whole sampling time were 0.11 ng/Nm3 (Leipzig), 0.17 ng/Nm3 (Roitzsch) and 0.37 ng/Nm3 (Greppin), the mean values of the HCH concentrations were 0.22 ng/Nm3 (Leipzig), 0.31 ng/Nm3 (Roitzsch) and 0.69 ng/Nm3 (Greppin). This increase of the concentration values from Leipzig over Roitzsch to Greppin indicates the influences of industrial waste sites in the Bitterfeld region on the atmospheric environment. The significantly higher values of hexachlorobenzene, alpha- and beta-HCH in Greppin are probably caused by emissions from the former chemical plant Bitterfeld-Wolfen and the landfill 'Antonie' near Greppin. Compared with literature data from other industrial impacted areas the measured air concentration and deposition values are relatively low.

Air Pollutants↗
PubMed1999

Biomonitoring of airborne inorganic and organic pollutants by means of pine tree barks. I. Temporal and spatial variations.

Scots pine (Pinus sylvestris L.) bark samples were collected at two field sites (Neuglobsow, Rösa) and in different years between 1987 and 1996 in the east of Germany. The barks were analyzed with respect to the following inorganic and organic substances: Al, As, B, Ca, Cd, Ce, Cr, Cu, Fe, Hg, Mo, NH4+, Ni, NO3-, PO4(3)-, Pb, Sr, SO4(2)-, Ti, V, W, Zr, Zn, benzo[a]pyrene, fluoranthene, pyrene, alpha-hexachlorocyclohexane (alpha-HCH) and dichlorodiphenyltrichloroethane (DDT). In addition to bark samples from the site Rösa, 53 test sites were investigated in the Nature Park Dübener Heide. Here, the analysis of the barks aimed at discovering spatial patterns of the above-mentioned substances. Since 1991, most of the determined substances (e.g. sulfate, nitrate, calcium, lead, benzo[a]pyrene, alpha-HCH) show decreased concentration values in bark samples from both sites. Temporal variations reflect substantial infra-structural changes in eastern Germany, especially at Rösa and in the industrial region around the cities Leipzig, Halle, and Bitterfeld. Moreover, nitrate concentrations in barks are increasing since 1995. The trend can be explained with increased nitrogen emissions from motor traffic and livestock farms. Spatial patterns of sulphate and ammonia reflect inputs from power plants and agriculture in pine stands of the Nature Park Dübener Heide. The results show that barks of pine trees can be used as biomonitoring tools to indicate and characterize depositions of airborne organic and inorganic pollutants.

Agriculture↗
PubMed1999

Seasonal impacts on beta-hexachlorocyclohexane concentration in soil solution.

We analysed monthly the concentration of beta-hexachlorocyclohexane (beta-HCH), a hydrophobic organic contaminant, in aqueous saturation extracts of the topsoil from five differently contaminated sites. beta-HCH concentration in the aqueous soil extract shows a high seasonal variability. Concentrations differ up to 60-fold with peaks up to 2.24 microg l(-1). Higher beta-HCH concentrations were found in summer and autumn and accompanied by peaks in dissolved organic carbon concentration. This indicates the importance of dissolved organic matter for beta-HCH mobilization and the risks for groundwater pollution and plant uptake.

Journal Article↗
PubMed1997

Determination of urinary acylcarnitines by ESI-MS coupled with solid-phase microextraction (SPME).

The determination of selected short-, medium- and long-chain acylcarnitines by electrospray ionization mass spectrometry (ESI-MS) is discussed. The differences in fragmentation behaviour and ionization efficiency are described in dependence on collision induced dissociation (CID) conditions and mixture composition. A new method combination, solid-phase microextraction (SPME)-ESI-MS, is introduced to characterize acylcarnitines in body fluids. This method utilizes SPME for pre-concentration of acylcarnitines from complex biological samples and ESI-MS for a selective and sensitive detection. The method is presented by standard experiments determining of acylcarnitines in aqueous solutions and urine samples from patients with secondary carnitine deficiency syndromes or related disorders.

Calibration↗
PubMed1983

Detection of gaseous pollutions in the environment and at work places by means of aerosol detectors.

The protection of the free atmosphere and of people at work places requires the development of highly sensitive devices for the assessment of the air-hygiene situation and for the continuous control after measures have been taken. Favourable properties for the solution of such problems are displayed by aerosol detectors, which are suitable for automatic continuous measurements (aerosol ionization gas analyzer AIG) and for applications in gas chromatography (AID-GC). Starting from the principle of measurement the main parameters and properties of both modes of detection for selected pollutions (SO2, NOx, NH3, Ni(CO)4, halocarbons, amines) are given and discussed with consideration of practical experience.

Air Ionization↗
PubMedDate not supplied

Determination of organochlorine pesticides and chlorobenzenes in strawberries by using accelerated solvent extraction combined with sorptive enrichment and gas chromatography/mass spectrometry.

An analytical scheme for the determination of several organochlorine pesticides like hexachlorocyclohexanes (HCHs) and DDX compounds (p,p'-DDE, p,p'-DDD, and p,p'-DDT) as well as chlorobenzenes in strawberries has been developed. The procedure is based on aqueous accelerated solvent extraction (ASE) followed by solid-phase microextraction (SPME) or stir bar sorptive extraction (SBSE) and subsequent thermodesorption-gas chromatography/mass spectrometry analysis. A 65 microm polydimethylsiloxane/ divinylbenzene fiber was chosen for the SPME experiments. Significant SPME and ASE parameters were optimized using spiked water and strawberry samples. For the ASE of the organochlorine compounds, a water-acetone mixture (90 + 10, v/v) as the extraction solvent, an extraction temperature of 120 degrees C, and 2 cycles of 10 min extraction proved optimal. The developed method was evaluated with respect to precision and limits of detection (LOD). The relative standard deviations of replicate ASE-SPME determinations (n = 5) were in the range of 4-24%. LOD values between 1 and 10 microg/kg were achieved with the exception of DDT and DDE (40 microg/kg). Using SBSE, the LOD of these compounds could be improved (2 and 5 microg/kg). The main advantages of this method are the avoidance of cleanup and concentration procedures as well as the significant reduction of the required volume of organic solvents. The described method was applied to the determination of the pollutants in strawberry samples collected from different allotment gardens in a potentially polluted area, the Bitterfeld-Wolfen region (Germany).

Chlorobenzenes↗