Coretta Bauer

Synthesis of a molecularly imprinted polymer and its application for microextraction by packed sorbent for the determination of fluoroquinolone related compounds in water.

Molecularly imprinted polymer (MIP) has been synthesized by precipitation polymerization using ciprofloxacin (CIP) as template for the analysis of fluoroquinolone antibiotics (FQs). This MIP material was packed as sorbent in a device for microextraction by packed sorbent (MEPS) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the analysis of selected FQs drugs including CIP, norfloxacin (NOR) and ofloxacin (OFLO) in municipal wastewater samples. In comparison to the new MIP-MEPS procedure, the target compounds were also determined by solid-phase extraction (MISPE) using the new molecular imprinted polymer material to validate the new MIP-MEPS method. The ability of the MIP for molecular recognition of CIP, NOR and OFLO was proved in presence of structurally different environmental relevant substances such as quinolones (Qs), flumequine (FLU), di(methyl)phthalate (DMP), technical 4-nonylphenol (NP), caffeine, Galaxolide(®), Tonalid(®), di(butyl)phthalate (DBP), Triclosan, bisphenol-A (BPA), carbamazepine, di(ethylhexyl)phthalate (DEHP), estradiol and octocrylene. The analysis of wastewater samples revealed the high selectivity of the synthesized polymer which was able to recognize and retain the target analytes by both extraction methods, the offline SPE with MIP material and the semi-automated MEPS packed with MIP material.

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.

High performance liquid chromatography-tandem mass spectrometry for the analysis of 10 pesticides in water: a comparison between membrane-assisted solvent extraction and solid phase extraction.

This work describes the application of two sample preparation methods: membrane-assisted solvent extraction (MASE) and solid phase extraction (SPE) in combination with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) for the determination of 10 pesticides in surface and ground water. Optimal extraction conditions for MASE were 60 min extraction time at 30 degrees C with a solvent volume of 100 microL toluene. 5 microL of the toluene extract were directly injected in the HPLC-MS-MS system. Concerning SPE, two materials were tested and C18 was superior to Oasis HLB. Complete desorption was ensured by desorbing the SPE (C18) cartridge with 3 mL of an acetonitrile/methanol mixture (1:1). After evaporation, the extract was injected in the analytical system. Analyte breakthrough was not found for the investigated compounds. For both methods, high extraction yields were achieved, in detail 71% (metalaxyl) till 105% (linuron) for MASE and 52% (ethiofencarb) till 77% (prometryne) for SPE (C18). Detection limits were in the low ng/L range for both methods and precision, expressed as the relative standard deviation (RSD) of the peak areas was below 13%. Five real water samples were analyzed applying both extraction methods. The results were in good agreement and standard addition proved that no matrix effects (such as ion suppression) occurred. In this comparison SPE has the potential of larger sensitivity whereas faster analysis and slightly better recoveries were achieved with MASE. MASE shows potential to be a promising alternative to the conventional off-line SPE concerning low to medium polar compounds.

Pesticide impact on aquatic invertebrates identified with Chemcatcher® passive samplers and the SPEARpesticides index

Pesticides negatively affect biodiversity and ecosystem function in aquatic environments. In the present study, we investigated the effects of pesticides on stream macroinvertebrates at 19 sites in a rural area dominated by forest cover and arable land in Central Germany. Pesticide exposure was quantified with Chemcatcher® passive samplers equipped with a diffusion-limiting membrane. Ecological effects on macroinvertebrate communities and on the ecosystem function detritus breakdown were identified using the indicator system SPEARpesticides and the leaf litter degradation rates, respectively. A decrease in the abundance of pesticide-vulnerable taxa and a reduction in leaf litter decomposition rates were observed at sites contaminated with the banned insecticide Carbofuran (Toxic Units≥-2.8), confirming the effect thresholds from previous studies. The results show that Chemcatcher® passive samplers with a diffusion-limiting membrane reliably detect ecologically relevant pesticide pollution, and we suggest Chemcatcher® passive samplers and SPEARpesticides as a promising combination to assess pesticide exposure and effects in rivers and streams.

Comparison of Stir Bar Sorptive Extraction and Solid Phase Extraction as Enrichment Techniques in Combination with Column Liquid Chromatography for the Determination of Polycyclic Aromatic Hydrocarbons in Water Samples

The commonly used solid-phase extraction (SPE) was compared with the recently developed stir bar sorptive extraction (SBSE) to determine EPA-PAHs from precipitation water samples. SPE was performed using C18 PAH-filled cartridges; magnetic stirring rods 10 mm long and coated with 0.5 mm (24 µL) polydimethylsiloxane were used for SBSE. Determination was performed by high performance liquid chromatography and fluorescence detection. The investigations were performed at a concentration level of 30 ng/L, adjusted to actual PAH concentration levels of precipitation water. The recoveries ranged between 54% (SBSE) and 20% (SPE) respectively and about 100%, while the standard deviation ( n = 5) varied in the range of 4.7-13.5% (SBSE) and 3.6-16.9% (SPE) except for the more volatile compounds acenaphthene and fluorene. The detection limits calculated were between 0.4 and 5.0 ng/L. Both techniques were applied to study the PAH contents of precipitation water of several polluted sites in the city of Halle (Saxony-Anhalt, Germany). The advantages and disadvantages of the methods used are discussed.