Luise Wennrich

Polycyclic Aromatic Hydrocarbon Burden in Fruit and Vegetable Species Cultivated in Allotments in an Industrial Area

The polycyclic aromatic hydrocarbon (PAH) burden of various fruit and vegetable species (strawberries, apples, tomatoes, lettuce, kohlrabi, potatoes, parsley and kale) cultivated in allotments in the industrial area of Bitterfeld-Wolfen (Germany) were determined. In addition, the garden soils of the sampling sites were analysed. The total PAH concentrations of fruit and vegetables investigated varied in the range of 1-120 µg/kg fresh weight, with the highest being found in parsley and kale. As the highest concentration of benzo(a)pyrene (BaP) was 0.55 µg/kg in a parsley sample, none of the samples exceeded the recommended BaP limit in vegetable foods of 1 µg/kg. A positive relationship between the total PAH burden and the cultivating site was only found for the more highly contaminated species parsley and kale. The total PAH concentrations in the garden soils ranged from 28 to about 7000 µg/kg dry weight.

Chapter 10 Membrane-enclosed sorptive coating for the monitoring of organic compounds in water

Publisher Summary This chapter presents an overview of theoretical aspects and design of the different membrane-enclosed sorptive coating (MESCO) sampler formats for water monitoring such as: polydimethylsiloxane (PDMS)-coated fiber enclosed in an low-density polyethylene (LDPE) membrane, PDMS-coated stir bar enclosed in a dialysis membrane bag (MESCO I), and Silicone material enclosed in an LDPE membrane (MESCO II). It summarizes the efforts to calibrate the samplers for several priority pollutants in laboratory studies and to test them under field conditions. The performance of the PDMS-coated fiber in LDPE membrane bag was tested by time-dependent exposure in a flow-through system at 19°C. The sampling rates obtained have been tabulated. MESCO I samplers were also tested in this flow-through apparatus. Due to its much larger sampling capacity, the standard semipermeable membrane device (SPMD) has up to five orders of magnitude higher sampling rates than the MESCO formats tested. Further flow-through calibration experiments showed that the sampling rates in MESCO I were not significantly affected by the flow velocity, within the tested range of exposure conditions.

GC Trace Analysis of Haloethers in Water — Comparison of Different Extraction Techniques

Abstract The capabilities of three extraction techniques (solid-phase microextraction, solid-phase extraction, and liquid-liquid extraction) for the GC trace analysis of di- and tetrachlorinated haloethers in natural water samples were studied. The extraction procedures are described and evaluated with respect to recoveries, precision and detection limits using FID and MS detection. The results are compared. Investigations of the matrix influence show that efficiency and precision of the extraction procedures tested are not significantly influenced by dissolved organic matter in the relevant concentration range. Combined with GC-MS in SIM mode all three extraction techniques are generally suitable for the haloether analysis at ng/L level. However, the precision of solid-phase microextraction (SPME) is poor in this concentration range. Nevertheless, because of several advantages (low time consuming for sample preparation, no employment of solvents) the SPME is favorable for the determination of haloethers ...

Gaschromatographische Untersuchung der Adsorptionseigenschaften von Silicalit und ZSM-5

High silica molecular sieves (silicalite, ZSM-5) were tested as adsorbents for gas chromatographic trace analysis. Therefore the retention behaviour of low-boiling organic compounds (hydrocarbons, halogenated hydrocarbons, amines, alcohols and ethers) on these materials was investigated. The specific retention volumes at different temperatures have been determined and elution orders and peak shapes were studied. The retention data allow a simple calculation of the breakthrough volumes (dynamic adsorption capacity) and the chromatographic characterisation of the adsorbents. Both nitrogen and oxygen containing compounds could not—or at least unreproducibely—be eluated up to 300°. The elution order and the peak shape of compounds with the same number of carbon atoms but different geometric and electronic structure (e.g.n-butenes;n-hexane, cyclohexane, benzene) can be explained by the action of exclusion effects and different diffusion barriers.On the basis of calculated breakthrough volumes we conclude that silicalite should be useful in the preconcentration of both saturated C3–C6 hydrocarbons and C1–C2 chlorinated hydrocarbons from gaseous streams.

Chapter 5 Membrane-enclosed sorptive coating as integrative sampler for monitoring organic compounds in air

Publisher Summary The membrane-enclosed sorptive coatings (MESCOs) for air sampling combine the benefits of a passive sampling system with those of analyzing the accumulated analytes by thermodesorption, while avoiding the use of solvents and laborious and expensive sample preparation and clean-up steps. The passive sampling devices developed are small, robust, and inexpensive. The receiving medium employed—stir bar, silicone tubing or silicone rod—can be reused after each deployment. The stable enveloping low-density polyethylene (LDPE) membrane makes the MESCOs of the type A robust for field experiments. On the other hand, the thin LDPE film of the MESCOs of the type B reduces the lag-phase. The results of the measurements with both sampler types show that the uptake of polychlorinated biphenyls (PCBs) and hexachlorocyclohexane (HCH) is linear over some weeks. Moreover, the passive sampling technique can detect time weighted average (TWA) air concentrations in the pg m -3 range and the passive samplers were successfully tested in a polluted area. Finally it should be mentioned that the scope of the MESCOs is not restricted to field air monitoring. For indoor air analysis, typically performed under nearly stationary conditions it is possible to determine TWA concentrations of SVOCs that are hardly to monitor with commercial devices at present.