Biomedical subjects

Peter Popp

Publications and source records attributed to Peter Popp.

25 records · Page 2Linked to original sources

PubMed2004

Dynamic extraction in rotating coiled columns, a new approach to direct recovery of polycyclic aromatic hydrocarbons from soils.

A new approach to the direct recovery of polycyclic aromatic hydrocarbons (PAHs) from environmental solid samples has been proposed. It has been shown that rotating coiled columns (RCCs) earlier used mainly in countercurrent chromatography can be successfully applied to the fast continuous-flow extraction of PAHs from soils. A particulate solid sample was retained in the rotating column as the stationary phase under the action of centrifugal forces while a mixture of organic solvents (acetone-cyclohexane, 1:1, v/v) was continuously pumped through. The separation procedure requires less than half an hour, complete automation being possible. No clean-up step is needed before the subsequent HPLC- analysis of extracts. Besides, the dynamic multistage extraction performed in the rotating column at room temperature and normal pressure may have nearly the same efficiency as accelerated batch solvent extraction repeated three times at 150 degrees C and 14 MPa. Contents of PAHs in extracts obtained by using both methods are in good agreement with the certified data on the PAHs concentrations in the soil samples. The use of appropriate "mild" solvents for the dynamic extraction in rotating columns may be very perspective for the simulation of naturally occurring processes and determination of environmentally-relevant forms of PAHs and other pollutants in environmental solids. A particular emphasis could be placed on time-resolved (kinetic) studies of the mobilization of toxicants in soil systems.

Chromatography, Liquid↗

PubMed2004

PCBs and HCHs in a salt-marsh sediment record from South-Central Chile: use of tsunami signatures and 137Cs fallout as temporal markers.

This paper documents the occurrence of polychlorinated biphenyl (PCB) and hexachlorocyclohexane (HCH) deposition inferred from a sedimentary record exposed in a salt-marsh trench in South-Central Chile. Sediments were carefully collected every 1 cm from the trench wall. The samples were analyzed for PCBs, HCHs, 137Cs, organic carbon and grain size. The 137Cs fallout and the sedimentary signature left by the 1960 Chilean tsunami were used as temporal markers to estimate the stratigraphic chronology and the sedimentation rates. PCBs were quantified by gas chromatography with electron capture detection (GC-ECD), and positive samples were confirmed by gas chromatography and mass spectrometry detection (GC-MS). Based on these results, PCBs and HCHs deposition over the last 40 years was estimated. No PCBs were detected below the tsunami signature. Total concentrations ranged from undetectable (ND) to 32 ng/g d.w. for PCBs and from undetectable (ND) to 1.29 ng/g d.w. for HCHs. The highest PCB concentrations were found in the upper 7 cm of the core. Even though PCBs were banned in 1982 as electrical fluids in Chile, total estimated PCB fluxes have increased approximately 20 times during the last 40 years: from undetectable values to 102.6 ng/cm2/year, reflecting that PCBs are still in use and being released into the environment.

Carbon↗

PubMed2003

Semi-automated hollow-fibre membrane extraction, a novel enrichment technique for the determination of biologically active compounds in water samples.

An automated hollow fibre membrane extraction technique was developed for the GC-MS determination of pharmaceutical and endocrine disrupting compounds in water samples. Enrichment was carried out inside a porous polypropylene hollow fibre membrane, which separated the aqueous and organic phases and regulated the transfer of analytes. n-Octanol placed inside the hollow fibre was used as the acceptor solution. A water-solvent ratio of about 300:1 was used to concentrate the analytes. After 1 hour's extraction of the water sample under magnetic stirring, 1 microl of the n-octanol phase was automatically injected from the hollow fibre into the GC-MS. Development work included examining the influence of different sample matrices, volumes, extraction times and extraction solvents. The detection limits, linearity and standard deviations of the method were determined using drugs such as ibuprofen, phenazone and carbamazepine as well as the endocrine disrupting compounds. technical nonylphenols, bisphenol A, 17alpha-ethinylestradiol and tonalide by way of example.

Automation↗

PubMed2003

Development of an integrative passive sampler for the monitoring of organic water pollutants.

The development of convenient and competitive devices and methods for monitoring of organic pollutants in the aquatic environment is of increasing interest. An integrative passive sampling system has been developed which consists of a solid poly(dimethylsiloxane) (PDMS) material (tube or rod), acting as hydrophobic organic receiving phase, enclosed in a water-filled or an air-filled low-density polyethylene (LDPE) membrane tubing. These samplers enable the direct analysis of the pollutants accumulated during exposure in the receiving phase by thermodesorption-GC/MS, avoiding expensive sample preparation and cleanups. The capabilities of these sampling devices were studied for the sampling of 20 persistent organic pollutants (chlorobenzenes, hexachlorocyclohexanes, p,p'-DDE, PAHs, and PCBs) in laboratory exposure experiments. For the three sampler designs investigated the uptake of all target analytes was integrative over exposure periods up to 9 days (except PCB 101). The determined sampling rates range from 4 to 1340 microl h(-1) for the water-filled samplers and from 20 to 6360 microl h(-1) for the air-filled ones, respectively. The sampling rate of the analytes is dependent on their molecular weight, partition between water and sampler media (PDMS, polyethylene, water, air) and also of the sampler design. The passive samplers enable the estimation of time-weighted average (TWA) concentration of water pollutants in the lower ng l(-1) to pg l(-1) range.

Dimethylpolysiloxanes↗

PubMed2002

Study of fungal degradation products of polycyclic aromatic hydrocarbons using gas chromatography with ion trap mass spectrometry detection.

Representatives of polycyclic aromatic hydrocarbons (PAHs) were degraded by ligninolytic fungus Irpex lacteus. The products were analyzed by GC-Ion trap mass spectrometry. The combination of full scan mass spectra, product ion scans (MS-MS) and derivatization of the degradation products of anthracene, phenanthrene, fluoranthene and pyrene provided further insight in the degradation mechanism initiated by I. lacteus. Particularly, the product ion scans enabled the interpretation of unknown degradation products, even though they were only produced at trace level. Most of the structures suggested were later confirmed with authentic standards.

Fungi↗

PubMed2002

Membrane-assisted solvent extraction of triazines and other semi-volatile contaminants directly coupled to large-volume injection-gas chromatography-mass spectrometric detection.

A simple device was developed for in-vial liquid-liquid extraction using a polymer membrane (nonporous polypropylene) to separate an aqueous sample from an organic extractant. The membrane consisted of tubing with an internal diameter of 6 mm and a wall thickness of 0.05 mm, which was heat-sealed at the lower end and filled with 500 microl hexane. This membrane bag was incorporated into a conventional 20 ml headspace vial suitable for a multi-purpose sampler (MPS 2, Gerstel, Mülheim, Germany) directly interfaced to a gas chromatograph with a mass-selective detector. The sampler enabled the extraction vial to be mixed at a defined temperature with subsequent large-volume injection of the organic extract taken from the membrane bag. The method was evaluated using several triazines, 2,4-dichloroaniline, alpha-hexachlorocyclohexane and phenanthrene as model compounds. Extraction parameters such as temperature, agitation speed, and extraction time were optimised. Recoveries of 60-90% were achieved after 30 min extraction. By increasing the injection volume to 100 microl, detection limits of 1-10 ng/l were determined.

Gas Chromatography-Mass Spectrometry↗

PubMed2002

Novel integrative passive samplers for the long-term monitoring of semivolatile organic air pollutants.

Two types of passive sampler were developed for the long-term monitoring of semivolatile organic compounds (SOCs) in air. They consist of poly(dimethylsiloxane) (PDMS)-coated stir bars (type A) or silicone tubing (type B), acting as a solid receiving medium, enclosed in a heat-sealed low-density polyethylene (LDPE) membrane. These samplers combine the advantages of integrative passive sampling with those of analysing accumulated analytes by thermodesorption-GC-MS, whilst avoiding the use of solvents and expensive sample preparation and cleanup steps. The performance of these samplers was investigated for the integrative sampling of SOCs, including alpha- and gamma-hexachlorocyclohexanes, hexachlorobenzene, 2,4,4'-trichlorobiphenyl, 2,2',5,5'-tetrachlorobiphenyl and fluoranthene, in laboratory exposure experiments under controlled conditions. For both types of sampler, the uptake of all the analytes investigated was linear over an exposure period of 15 days. The sampling rates calculated ranged from 70 to 320 ml h(-1) (sampler A) and 630 to 4300 ml h(-1) (sampler B). The passive samplers are able to detect low time-weighted average air concentrations in the pg m(-3) range. The small, robust and inexpensive sampling devices were tested successfully for the long-term air monitoring of semivolatile organic pollutants in a polluted area over an exposure period of up to 28 days.

Air Pollution, Indoor↗