Albrecht Paschke

Application of accelerated solvent extraction followed by gas chromatography, high-performance liquid chromatography and gas chromatography–mass spectrometry for the determination of polycyclic aromatic hydrocarbons, chlorinated pesticides and polychlorinated dibenzo-p-dioxins and dibenzofurans in solid wastes

Accelerated solvent extraction (ASE) is a new method for the extraction of organic compounds from soils, sludges and other wastes. Due to the elevated temperatures and pressures, the ASE is a time-saving procedure with low consumption of solvents. Applications of this procedure for the determination of chlorinated pesticides in contaminated soils, for the determination of polycyclic aromatic hydrocarbons in heap material, slurry from copper smelting (Theissenschlamm) and soils and for the determination of polychlorinated dibenzo-p-dioxins and dibenzofurans in a fly ash sample are given. Optimization of the procedure relating to extraction time, number of extractions and solvents is described. Comparisons with other extraction methods (Soxhlet extraction and automated Soxhlet extraction) are carried out.

Air–Water Partitioning of 222Rn and its Dependence on Water Temperature and Salinity

Radon is useful as a tracer of certain geophysical processes in marine and aquatic environments. Recent applications include detection of groundwater discharges into surface waters and assessment of air/sea gas piston velocities. Much of the research performed in the past decade has relied on continuous measurements made in the field using a radon stripping unit connected to a radon-in-air detection system. This approach assumes that chemical equilibrium is attained between the water and gas phases and that the resulting air activity can be multiplied by a partition coefficient to obtain the corresponding radon-in-water activity. We report here the results of a series of laboratory experiments that describes the dependence of the partition coefficient upon both water temperature and salinity. Our results show that the temperature dependence for freshwater closely matches results that were previously available. The salinity effect, however, has largely been ignored and our results show that this can result in an overestimation of radon concentrations, especially in cooler, more saline waters. Related overestimates in typical situations range between 10 (warmer less saline waters) and 20% (cooler, more saline waters).

Selective determination of estrogenic compounds in water by microextraction by packed sorbents and a molecularly imprinted polymer coupled with large volume injection-in-port-derivatization gas chromatography–mass spectrometry

A fully automated protocol consisting of microextraction by packed sorbents (MEPS) coupled with large volume injection-in-port-derivatization-gas chromatography-mass spectrometry (LVI-derivatization-GC-MS) was developed to determine endocrine disrupting compounds (EDCs) such as alkylphenols, bisphenol A, and natural and synthetic hormons in river and waste water samples. During method optimization, the extraction parameters as ion strength of the water sample, the MEPS extraction regime, the volume of organic solvent used for the elution/injection step, the type of elution solvents and the selectivity of the sorbents were studied. For optimum in-port-derivatization, 10 μL of the derivatization reagent N,O-bis(trimethylsilyl)triufloroacetamide with 1% of trimethylchlorosilane (BSTFA+1% TMCS) was used. 17β-Estradiol-molecularly imprinted polymer (MIP) and silica gel (modified with C-18) sorbents were examined for the enrichment of the target analytes from water samples and the obtained results revealed the high selectivity of the MIP material for extraction of substances with estrogen-like structures. Recovery values for most of the analytes ranged from 75 to 109% for the C18 sorbent and from 81 to 103% for the MIP material except for equilin (on C18 with only 57-66% recovery). Precision (n=4) of the entire analysis protocol ranged between 4% and 22% with both sorbents. Limits of detection (LODs) were at the low ngL(-1) level (0.02-87, C18 and 1.3-22, MIP) for the target analytes.

Determination of polycyclic aromatic hydrocarbons in waste water by off-line coupling of solid-phase microextraction with column liquid chromatography

A new method for the determination of polycyclic aromatic hydrocarbons (PAHs) in waste water using solvent-free solid-phase microextraction (SPME) is described. The PAHs are extracted with a 100 microm polydimethylsiloxane (PDMS) fiber, desorbed in 40 microl acetonitrile and measured with LC and fluorescence detection. The detection limits of this very simple method under the given conditions (extraction from 5 ml sample, extraction time 1 h) are in the range of 1-6 ng l(-1). The standard deviations (n = 6) at a concentration level of 0.8 microg l(-1) are between 1.8 and 14.4%. The procedure was used for the determination of PAHs in contaminated water samples.

Performance of the Chemcatcher® passive sampler when used to monitor 10 polar and semi-polar pesticides in 16 Central European streams, and comparison with two other sampling methods

We investigated the performance of the Chemcatcher, an aquatic passive sampling device consisting of a sampler body and an Empore disk as receiving phase, when used to monitor acetochlor, alachlor, carbofuran, chlorfenvinphos, alpha-endosulfan, fenpropidin, linuron, oxadiazon, pirimicarb and tebuconazole in 16 Central European streams. The Chemcatcher, equipped with an SDB-XC Empore disk, detected seven of the aforementioned pesticides with a total of 54 detections. The time-weighted average (TWA) concentrations reached up to 1 microg/L for acetochlor and alachlor. Toxic units derived from these concentrations explained reasonably well the observed ecological effects of pesticide stress, measured with the SPEAR index. In a follow-up analysis, we compared the Chemcatcher performance with those of two other sampling systems. The results obtained with the Chemcatcher closely matched those of the event-driven water sampler. By contrast, the TWA concentrations were not significantly correlated with concentrations on suspended particles. We conclude that the Chemcatcher is suitable for the monitoring of polar organic toxicants and presents an alternative to conventional spot sampling in the monitoring of episodically occurring pollutants.

Towards a renewed research agenda in ecotoxicology

New concerns about biodiversity, ecosystem services and human health triggered several new regulations increasing the need for sound ecotoxicological risk assessment. The PEER network aims to share its view on the research issues that this challenges. PEER scientists call for an improved biologically relevant exposure assessment. They promote comprehensive effect assessment at several biological levels. Biological traits should be used for Environmental risk assessment (ERA) as promising tools to better understand relationships between structure and functioning of ecosystems. The use of modern high throughput methods could also enhance the amount of data for a better risk assessment. Improved models coping with multiple stressors or biological levels are necessary to answer for a more scientifically based risk assessment. Those methods must be embedded within life cycle analysis or economical models for efficient regulations. Joint research programmes involving humanities with ecological sciences should be developed for a sound risk management.

Silicone rod and silicone tube sorptive extraction.

This review focuses on the applications of silicone in the form of tubes or rods for sorptive extraction of organic compounds as sample preparation method in combination with various chromatographic techniques. Silicone rods (SRs) and silicone tubes (STs) have the advantage of being inexpensive, flexible and robust. SRs and STs with different sizes and volumes of silicone (8-635microL) have so far been applied for the extraction/preconcentration of a large variety of organic micropollutants from different matrices. The theoretical principle of SR and ST extraction in comparison with similar microextraction techniques is presented as well as a summary of the published applications of SR and ST extraction in combination with gas chromatography (GC) or liquid chromatography (LC). Furthermore, the use of SRs and STs for time-integrated (passive) sampling is reported.

How to deal with lipophilic and volatile organic substances in microtiter plate assays

Microtiter plate-based assays are a promising technique for toxicity assessment of substances. Chemicals with physicochemical properties such as high volatility and/or high lipophilicity, however, can be lost from the exposure solution during an experiment, so that exposure concentrations are not consistent. The aim of the present study was to determine and reduce the proportion of the reference compounds phenanthrene and phenanthridine lost during exposure in the zebra fish (Danio rerio) embryo test regime. It could be shown that under the standard exposure regime (48 h), the concentration of phenanthrene decreased strongly, by more than 99%, whereas that of phenanthridine decreased by 17% during a 48-h experiment. After modifications to the microtiter plate exposure regime, the phenanthrene concentration showed a decrease of only 40%, while the phenanthridine concentration remained unchanged. The major processes of substance loss could be assigned to accumulations of these substances into the glue of commercially available adhesive foils and the polystyrene walls of the microtiter plates. Furthermore, by investigating the sorption capacity of different plastics, it was found that the phenanthrene concentration decreased less when using a plexiglass specimen (28%) compared with the same-sized polystyrene specimen (94%). Moreover, it was found, for a constant exposure regime, that concentration profiles of different phenanthrene concentrations in the microtiter plate assay during an experiment were similar. A mathematical method is proposed to predict concentration profiles in an exposure solution by scaling a determined profile.

Use of semipermeable membrane devices (SPMDs). Determination of bioavailable, organic, waterborne contaminants in the industrial region of Bitterfeld, Saxony-Anhalt, Germany.

Triolein-containing semipermeable membrane devices (SPMDs) were employed as passive samplers to provide data on the bioavailable fraction of organic, waterborne, organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polynuclear aromatic hydrocarbons (PAHs) in streams flowing through a highly polluted industrial area of Bitterfeld in Saxony-Anhalt, Germany. The contamination of the region with organic pollutants originates in wastewater effluents from the chemical industry, from over one-hundred years of lignite exploitation, and from chemical waste dumps. The main objective was to characterise time-integrated levels of dissolved contaminants, to use them for identification of spatial trends of contamination, and their relationship to potential pollution sources. SPMDs were deployed for 43 days in the summer of 1998 at four sampling sites. The total concentration of pollutants at sampling sites was found to range from a low of 0.8 μg/SPMD to 25 μg/ SPMD for PAHs, and from 0.4 ug/SPMD to 22 μg/SPMD for OCPs, respectively. None of the selected PCB congeners was present at quantifiable levels at any sampling site. A point source of water pollution with OCPs and PAHs was identified in the river system considering the total contaminant concentrations and the distribution of individual compounds accumulated by SPMDs at different sampling sites. SPMD-data was also used to estimate average ambient water concentrations of the contaminants at each field site and compared with concentrations measured in bulk water extracts. The truly dissolved or bioavailable portion of contaminants at different sampling sites ranged from 4% to 86% for the PAHs, and from 8% to 18% for the OCPs included in the estimation. The fraction of individual compounds found in the freely dissolved form can be attributed to the range of their hydrophobicity. In comparison with liquid/liquid extraction of water samples, the SPMD method is more suitable for an assessment of the background concentrations of hydrophobic organic contaminants because of substantially lower method quantification limits. Moreover, contaminant residues sequestered by the SPMDs represent an estimation of the dissolved or readily bioavailable concentration of hydrophobic contaminants in water, which is not provided by most analytical approaches.

Influence of food limitation on the effects of fenvalerate pulse exposure on the life history and population growth rate of Daphnia magna

Laboratory ecotoxicity tests may not adequately evaluate the effects of pesticides, because they often do not include more environmentally relevant conditions, such as pulsed toxicant exposures and low food conditions. Therefore, we tested the effects of a pulse of the pyrethroid insecticide fenvalerate (FV) on the life history and population growth rate (r) of the cladoceran Daphnia magna. The daphnids were subjected to a 24-h pesticide pulse exposure (0.03, 0.1, 0.3, 0.6, 1.0, and 3.2 microg/L) under high and low food conditions and were monitored for 21 d. Chemical analysis showed that at t = 1 h, the nominal FV concentrations were reduced by 50 to 66%. Fenvalerate decreased survival and growth in the week following pulse exposure. Age at first reproduction increased, with consequent adverse effects on cumulative reproduction per living female and, therefore, on r. Thus, a short-term exposure of FV caused a long-term reduction on r as a result of increased mortality and a delay in development. Low food conditions exacerbated the effects of the FV exposure on juvenile survival and growth during the first week. This caused a much stronger reduction in r under low food conditions. We concluded that a pulsed FV exposure may result in long-term reduction of r that can be predicted only with more environmentally relevant toxicity tests, as described in the present study.