Search

The combination of ultrafiltration (UF) and powdered activated carbon (PAC) has gained in importance over the last 15 years. The aim of applying PAC-UF hybrid processes is to improve the rejection capacity and the performance of membrane processes. In this work the influence of PAC-addition on membrane flux decline and fouling formation was studied with a submerged module using different water matrices. The PACs used were characterized by measurements of the surface area, the particle size distribution and the surface charge to get a better understanding of the observed effects. Results showed that the membrane flux decline was dependent on the applied type of activated carbon. When adding Picachem 8P, the transmembrane pressure (TMP) increased very quickly and the membrane performance was even worse than that without PAC. However, when adding Norit SA-UF under identical filtration conditions, the TMP was stable and the membrane performance was better than that without PAC. The fouling layers of the two PACs applied showed entirely different structures. Therefore the selection of a suitable PAC is a main factor for the overall performance of PAC-UF hybrid systems with submerged membranes.

Anaerobic degradation processes play an important role in contaminated aquifers. To indicate active biodegradation processes signature metabolites can be used. In this study field samples from a high-resolution multilevel well in a tar oil-contaminated, anoxic aquifer were analyzed for metabolites by liquid chromatography-tandem mass spectrometry and time-of-flight mass spectrometry. In addition to already known specific degradation products of toluene, xylenes, and naphthalenes, the seldom reported degradation products benzothiophenemethylsuccinic acid (BTMS), benzofuranmethylsuccinic acid (BFMS), methylnaphthyl-2-methylsuccinic acid (MNMS), and acenaphthene-5-carboxylic acid (AC) could be identified (BFMS, AC) and tentatively identified (BTMS, MNMS). The occurrence of BTMS and BFMS clearly show that the fumarate addition pathway, known for toluene and methylnaphthalene, is also important for the anaerobic degradation of heterocyclic contaminants in aquifers. The molar concentration ratios of metabolites and their related parent compounds differ over a wide range which shows that there is no simple and consistent quantitative relation. However, generally higher ratios were found for the more recalcitrant compounds, which are putatively cometabolically degraded (e.g., 2-carboxybenzothiophene and acenaphthene-5-carboxylic acid), indicating an accumulation of these metabolites. Vertical concentration profiles of benzylsuccinic acid (BS) and methyl-benzylsuccinic acid (MBS) showed distinct peaks at the fringes of the toluene and xylene plume indicating hot spots of biodegradation activity and supporting the plume fringe concept. However, there are some compounds which show a different vertical distribution with the most prominent concentrations where also the precursor compounds peaked.

Herein we report on the photocatalytic degradation of natural organic matter from a bog lake (Lake Hohloh, Black Forest, Germany) as followed by size exclusion chromatography with dissolved organic carbon (DOC) and ultraviolet ( λ = 254 nm) detection (SEC-DOC and SEC-UV). When irradiating this humic-rich water in the presence of 0.5 g L−1 titanium dioxide (P25), we found a preferential degradation of the higher molecular weight DOC fraction. This was coupled to growth of the middle and small DOC fractions. Mineralization proceeded in two distinct steps: a first stage without noticeable mineralization, followed by a phase of steady decrease in dissolved organic carbon. Formic, oxalic, succinic and glutaric acids were found in the irradiated samples and contribute significantly to the bioavailable DOC after irradiation, which favors bacterial regrowth.

The evaluation of the molecular size distribution of natural organic matter (NOM) in aquatic environments via size exclusion chromatography (SEC) is important for the understanding of environmental processes such as nutrient cycling and pollutant transport as well as of technical water treatment processes. The use of organic carbon (OC) detectors has become popular in recent studies due to improved availability and quantification possibilities, which supposedly are superior to those of ultraviolet (UV) detectors. A set of 12 NOM samples was used to demonstrate the limitations of online OC detection (OCD) when analyzing complex aquatic organic matter. A novel evaluation approach for SEC data is introduced by combining the information from UV absorbance (UVA) and OCD chromatograms as well as offline total OC (t-OC) and dissolved OC-specific UVA (SUVA) measurements. It could be shown that about 70% of certain OC components were not detected with the OCD system used in this study. For the investigated samples, these types of carbon accounted for up to 72% of the t-OC, i.e. for such NOM samples quantification by OCD is not possible or at least highly questionable. The addition of an oxidant improved the overall oxidation efficiency only slightly. Most likely NOM that predominantly consists of polysaccharides and features a nominal molecular weight of 150 kg/mol or more was responsible for low OCD yields. For future applications, a further improvement of the OCD system would be worthwhile so that quantitative analytical data on the molecular size distribution of NOM and its structural characteristics such as the SUVA distribution can be obtained.

The efficiency of binding during enzyme immobilisation does not only depend on the chemical properties of the enzyme and the matrix particle, but also on their surface potential. Zeta potential quantifies the electrostatic interactions between enzyme and matrix particles, and can therefore, be used as an indicator of the binding efficiency in the enzyme immobilisation studies. In order to establish a correlation between the zeta potential and the binding efficiency, we used CALA (Candida antarctica A-type lipase) as a model protein for immobilisation on non-porous magnetic microparticles with epoxy (M-PVA E02), carboxy (M-PVA C12) and amine (M-PVA N12) terminations. We observed maximal binding of CALA onto the M-PVA N12 beads, due to the electrostatic attraction between negatively charged protein and carrier particles with slightly positive zeta potential. The binding of CALA was lower when M-PVA E02 beads were used, followed by M-PVA C12 beads. The decreasing binding efficiency was obviously the result of increasing electrostatic repulsion between the interaction partners. This could be correlated to the increasing negative zeta potential of the magnetic particles. Moreover, the medium of suspension of the particles also makes a significant difference. We found highest specific activity of the lipase immobilised on M-PVA E02 beads in a medium concentrated buffer (0.3 M). The results demonstrate a clear correlation between zeta potential and binding efficiency but no correlation between the bead related specific activity and the zeta potential. These findings are advocating the possibility of using the zeta potential as a diagnostic tool in enzyme immobilisation.

The application of membrane filtration in the treatment of spent filter backwash water (SFBW) permits efficient removal of microorganisms, suspended particles and organic substances, depending on the used membrane molecular weight cut-off. However, flux decline, due to deposits and adsorption of substances (salts, colloids, organics, particles, microorganisms, etc.) tends to limit the use of membranes. Characterization of SFBW samples from different waterworks showed that three major factors contribute to the SFBW properties: the raw water itself, the time interval of sand filter operation and additional treatment steps. The main differences between SFBW samples were found principally in DOC, TOC and turbidity. Experiments with submerged membranes (lab- and pilot- scale modules) showed that there was a clear correlation between DOC concentration of the feed and the flux decline: when the DOC-concentration increased, the flux decline increased. Additionally, the presence of calcium led not only to an important flux decline but to high adsorption of NOM on the membrane surface. Iron concentrations in the micromolar range resulted in a considerably decline of flux. Filtration of SFBW revealed that the decline of permeability is mainly determined by DOC, calcium and iron concentrations. A decisive effect of biofouling on membrane performance is expected for long term experiments.

The effects of four different filtration modes (i.e. relaxation, backwash, mixed and continuous) producing the same flux productivity (time average flux) on membrane fouling were investigated in membrane bioreactors (MBRs). The fouling behaviour was found to be strongly dependent on the applied instantaneous flux rather than the filtration modes themselves. The transmembrane pressure (TMP) obtained after 24 h of filtration was dominated by the fouling rates calculated within the first hour of the experiment. After the filtration experiments, the resulting fouling layers were fractionated by rinsing, backwashing and then chemical cleaning, with the foulant removal reflecting the strength of attachment to the membrane. An analysis of the three different fouling layers provided a unique insight into the composition (protein and carbohydrate) and spatial distribution of the particulate and soluble foulants. The upper fouling fraction consists of a porous, loosely bound cake layer with a similar composition to the biomass flocs. The intermediate fraction, which consists of equal parts of soluble molecular products (SMP) and biomass aggregates, features a higher concentration of carbohydrates and possibly plays a significant in the formation of consecutive cake layer. The lower fraction, representing the irreversible fouling fraction and predominantly consisting of SMP, features a relative higher concentration of strongly bound proteins. Whereas the lower and the intermediate fractions showed similar properties for all filtration modes, the upper fraction was influenced by the instantaneous flux.

The combination of semiconductor photocatalysis with cross-flow microfiltration accompanied by periodical back-washing was investigated in a pilot plant. The investigation included the testing of membrane materials because the membrane must resist the abrasion and the periodical back-washing. Another objective of this investigation was to assess the potential of two different TiO(2) materials (Hombikat UV100 and P25) for continuous photocatalytic degradation of persistent organic pollutants. The study focused on the long-term stability of the photocatalytic activity of TiO(2) during its continuous application. The combination of photocatalysis and cross-flow microfiltration allowed the separation and reuse of TiO(2) after the photocatalytic degradation of clofibric acid, carbamazepine and iomeprol. The investigations showed that the photocatalytic activity of P25 and Hombikat UV100 was constant during continuous usage over several days. This study indicates the high potential of the combination of heterogeneous photocatalytic oxidation processes with cross-flow microfiltration accompanied by periodical back-washing of the membrane. Thus environmentally relevant pharmaceuticals and X-ray contrast media can be transformed and mineralized in a continuous water treatment process.

A full-scale (110 ML/d) potable water treatment plant (WTP) based on the MIEX process, an innovative new process based on a strong base anion-exchange resin with magnetic properties, has been operating in Perth Western Australia since 2001. This plant has been configured so that a combined MIEX-coagulation (MIEX-C) process can be operated in parallel with a conventional enhanced coagulation (EC) process, allowing comparison of the performance of the two processes. Here, we report the use of size exclusion chromatography (SEC) to compare the removal of different apparent molecular weight (AMW) fractions of DOC by the two processes. Water was sampled from five key locations within the WTP, and SEC was carried out using three different on-line detector systems, DOC-specific detection, UV absorbance detection at lambda = 254 nm, and fluorescence detection (lambda(ex) = 282 nm; lambda(em) = 353 nm). This approach provided information on the chemical nature of the DOC comprising the various AMW fractions. The study showed that the MIEX-C process outperformed the EC process with greater removal of DOC in each of the eight separate AMW fractions identified. While EC preferentially removed the fractions of highest AMW, and those exhibiting the greatest aromatic (humic) character, MIEX-C removed DOC across all AMW fractions and did not appear to discriminate as strongly on the basis of differences in aromatic character or AMW. The results demonstrate the benefits of combining these complementary treatment processes. The study also demonstrates the utility of SEC coupled with multiple detection systems in determining the characteristics of various AMW components of DOC.

Due to defects in sewerage systems, wastewater might contaminate groundwater. The aim of the study was to analyse the removal efficiency of organic matter from wastewater after trickling through columns filled with sand. Size-exclusion chromatography (SEC) coupled to on-line UV, dissolved organic carbon (DOC), and dissolved nitrogen (DN) detection as well as the analysis of amino acids (AA) and carbohydrates (CH) were employed as analytical tools to investigate structural changes of the dissolved organic matter (DOM). The DOC removal in the columns accounted for about 80 % based on the DOC concentration of the influent. The chromatograms gained by DOC detection showed three fractions: 1) colloids and polysaccharides, 2) humic material, and 3) low-molecular-weight compounds. The DOM present in fractions 1 and 3 was removed to a much higher extent (95 %, 90 %) than the DOM in fraction 2 (54 %) indicating ongoing humification processes. At the same time, highly bioavailable organic N compounds were lost, whereas N fractions bound to humic material remained. AA and CH belonged to the bioavailable fraction of the DOM. Despite the considerable variations of the ratios of AA and CH carbon to the DOC, a fairly constant pattern of the relative concentrations of the compounds was found. After acid hydrolysis of the column inflows, the AA pattern was dominated by glycine, alanine, glutamic acid, and aspartic acid, and the CH pattern by glucose. The relatively high concentrations of rhamnose and fucose in comparison to arabinose and xylose showed the strong microbial influence on the DOM composition. Transformation abwasserburtiger, geloster organischer Materie unterhalb von Kanalleckagen — Verbleib von Aminosauren und Kohlenhydraten Als Folge von Schaden im Kanalsystem kann es zur Verunreinigung von Grundwasser durch Abwasser kommen. Das Ziel dieser Arbeiten war es, die Effizienz der Eliminierung der organischen Materie von Abwasser bei Versickerung in mit Sand gefullten Saulen zu untersuchen. Zur Charakterisierung der strukturellen Veranderungen der gelosten organischen Materie (DOM) wurden die Grosenausschlusschromatographie gekoppelt mit Online-Detektion der UV-Absorption, des gelosten organischen Kohlenstoffs (DOC) und des gelosten Stickstoffs (DN) sowie die Analytik von Aminosauren (AA) und Kohlenhydraten (CH) eingesetzt. Die DOC-Eliminierung in den Saulen betrug etwa 80 %, bezogen auf die DOC-Konzentration des Zulaufs. Die Chromatogramme mit DOC-Detektion zeigten drei Fraktionen: 1) Kolloide und Polysaccharide, 2) huminstoffartiges Material und 3) niedermolekulare Verbindungen. Die DOM der Fraktionen 1 und 3 wurde in einem viel groseren Ausmas eliminiert (95 %, 90 %) als die DOM der Fraktion 2 (54 %), was auf fortschreitende Humifizierung hindeutet. AA und CH gehorten zur bioverfugbaren Fraktion der DOM. Trotz beachtlicher Variationen bezuglich der Konzentrationen an AA- und CH-Kohlenstoff, bezogen auf den DOC, wurde ein relativ konstantes Muster bezuglich der relativen Konzentrationen gefunden. Glycin, Alanin, Asparaginsaure und Glutaminsaure wurden als wichtigste AA nach Saurehydrolyse in den Saulenzulaufen nachgewiesen, Glucose als wichtigstes CH. Die in Bezug auf Arabinose und Xylose relativ hohen Konzentrationen an Rhamnose und Fucose zeigten den starken mikrobiellen Einfluss auf die Zusammensetzung der DOM.

An overview of different characterization methods and the possibilities for describing structural elements of humic substances from aqueous environments (HS, or refractory organic substances (ROS)) is given within this review. The application of different analytical methods for the qualitative and quantitative characterization of HS, including physical/chemical analysis (elemental analysis, acid/base titration), spectroscopic methods (UV/VIS, NMR, fluorescence, mass spectrometry), fractionation methods (gel chromatography, flow-field-flow-fractionation), and degradation methods (oxidation, pyrolysis, hydrolysis) are discussed. The paper focuses on the most commonly used chemical, spectroscopic and chromatographic methods used in the last few years. Aspects concerning information related to newer procedures are considered. Case studies representing results gained from reference samples isolated from brown water and wastewater effluents are given to cross-check results gained from several methods. The influence of different isolation procedures on the specific character of the fractions is also discussed.

Environmental contaminants of recent concern are pharmaceuticals, estrogens and other endocrine disrupting chemicals (EDC) such as degradation products of surfactants, algal and cyanobacterial toxins, disinfection by-products (DBPs) and metalloids. In addition, pesticides (especially their transformation products), microorganisms, and humic substances (HS), in their function as vehicles for contaminants and as precursors for by-products in water treatment, traditionally play an important role. The present status of the application of LC-MS techniques for these water constituents are discussed and examples of application are given. Solid-phase extraction with various non-selective materials in combination with liquid chromatography (LC) on reversed-phase columns have been the most widely used methods for sample preconcentration and separation for different compound classes like pesticides, pharmaceuticals or estrogens. Electrospray ionization (ESI) and atmospheric pressure ionization (APCI) are the most frequently used ionization techniques for polar and ionic compounds, as well as for less polar non-ionic ones. The facilities of LC-MS have been successfully demonstrated for different compound classes. Polar compounds from pharmaceuticals used as betablockers, iodinated X-ray contrast media, or estrogens have been determined without derivatization down to ultratrace concentrations. LC-MS can be viewed as a prerequisite for the determination of algal and cyanobacterial toxins and the homologues and oligomers of alkylphenol ethoxylates and their metabolites. Tandem mass spectrometric techniques and the use of diagnostic ions reveal their usefulness for compound-class specific screening and unknown identification, and are also valid for the analysis of pesticides and especially for their transformation products. Structural information has been gained by the application of LC-MS methods to organometallic species. New insights into the structural variety of humic substances have been made possible by FT-ICR-MS due to its ultrahigh mass resolution. Finally, exciting possibilities for rapid detection and identification of microorganisms have been made possible by MALDI and LC-MS methods.

LC-MS has become an invaluable technique for trace analysis of polar compounds in aqueous samples of the environment and in water treatment. LC-MS is of particular importance due to the impetus it has provided for research into the occurrence and fate of polar contaminants, and of their even more polar transformation products. Mass spectrometric detection and identification is most widely used in combination with sample preconcentration, chromatographic separation and atmospheric pressure ionization (API). The focus of the first part of this review is directed particularly toward instruments and method development with respect to their applications for detecting emerging contaminants, microorganisms and humic substances (HS). The current status and future perspectives of 1) mass analyzers, 2) ionization techniques to interface liquid chromatography (LC) with mass spectrometry (MS), 3) methods for preconcentration and separation with respect to their application for water analysis are discussed and examples of applications are given. Quadrupole and ion trap mass analyzers with electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) are already applied in routine analysis. Time-of-flight (TOF) mass spectrometers are of particular interest for accurate mass measurements for identification of unknowns. For non-polar compounds, different ionization approaches have been described, such as atmospheric pressure photoionization (APPI), electrochemistry with ESI, or electron capture ionization with APCI. In sample preconcentration and separation, solid phase extraction (SPE) with different non-selective sorbent materials and HPLC on reversed-phase materials (RP-HPLC) play the dominant role. In addition, various on-line and miniaturized approaches for sample extraction and sample introduction into the MS have been used. Ion chromatography (IC), size-exclusion chromatography (SEC), and capillary electrophoresis (CE) are alternative separation techniques. Furthermore, the issues of compound identification, matrix effects on quantitation, development of mass spectral libraries and the topic of connecting analysis and toxicity bioassays are addressed.

The primary degradation of a technical nonylphenol ethoxylate surfactant with an average chain length of 10 ethoxylate units (NPEO-10) was studied in a flow-through system by means of miniaturized biofilm reactors (mBFR) with bacteria from an activated sludge plant. 5 mg/L of the test compound (total EO concentration) were spiked in synthetic wastewater (SWW) and fed to the reactors continuously for 64 days. Compound removal and the formation of degradation products (DP) were monitored under both oxic and anoxic conditions. Solid-phase extraction and RP-HPLC with fluorescence detection were employed for sample preparation and analysis. Better removal of the parent compound was seen with the oxic reactors (50 to 70%) than with the anoxic reactors (30 to 50%). Compared to SWW organic matter, the test compound proved to be of refractory nature. The appearance of degradation products in the effluent was earlier with anoxic reactors despite their lower elimination efficiency. After extraction of biomass only minor amounts of NPEO-10 and metabolites were found, indicating that small amounts were present in adsorbed or intracellular form. Ultimate biodegradation of NPEO-10 and of octylphenol ethoxylates (OPEO-9.5; average chain length of 9.5 EO units) was tested by means of manometric respirometry at a theoretical oxygen demand (ThOD) of 100 mg/L. Whereas NPEO-10 was biodegraded by only 26%, at best, in 28 days, OPEO-9.5 degradation amounted to (40 ± 5)%. Biologischer Abbau von Nonylphenolethoxylaten in Biofilmreaktoren Der Primarabbau eines technischen Nonylphenolethoxylat-Gemisches mit einer durchschnittlichen Kettenlange von 10 Ethoxygruppen (NPEO-10) wurde unter Verwendung von miniaturisierten Biofilmreaktoren (mBFR) untersucht. Die Reaktoren wurden mit Biomasse aus der Belebungsstufe einer kommunalen Klaranlage inokuliert und als Durchfluss-Testsystem uber eine Dauer von 64 Tagen betrieben. Die Konzentration an NPEO-10 betrug 5 mg/L (Gesamtkonzentration aller Ethoxylate) in einer Matrix aus synthetischem Abwasser. Die Elimination der Testsubstanz sowie die Bildung von Abbauprodukten wurde unter oxischen und anoxischen Bedingungen untersucht. Als analytische Methoden wurden Festphasenextraktion und RP-HPLC mit Fluoreszenzdetektion eingesetzt. In den oxischen Reaktoren (50…70% Elimination) konnte eine bessere NPEO-10-Elimination erreicht werden als in den anoxischen Reaktoren (30…50% Elimination). Die Testsubstanz erwies sich als refraktarer gegenuber biologischem Abbau als die organische Substanz des synthetischen Abwassers. Trotz der geringeren Eliminationsleistung der anoxischen Reaktoren wurden dort fruher Abbauprodukte im Reaktorablauf beobachtet als in den oxischen mBFR. Nach Extraktion der Biomasse der Testreaktoren konnten nur geringe Mengen an NPEO-10 und Abbauprodukten gefunden werden, was zeigte, dass nur ein kleiner Teil in adsorbierter oder intrazellularer Form vorlag. In einem geschlossenen Respirometer wurde die vollstandige biologische Abbaubarkeit von NPEO-10 sowie eines Octylphenolethoxylat-Gemisches (OPEO-9.5; durchschnittliche Kettenlange von 9.5 Ethoxygruppen) bei einem theoretischen Sauerstoffbedarf (ThOD) von 100 mg/L untersucht. Wahrend NPEO-10 nur zu maximal 26% des ThOD abgebaut wurde, wurde fur OPEO-9.5 ein Abbau von (40 ± 5)% erreicht.

The biodegradation of three active compounds of pharmaceuticals clofibric acid, ibuprofen, and diclofenac was investigated in short-term tests with a pilot sewage plant (PSP) and biofilm reactors (BFR, oxic and anoxic) as model systems for municipal sewage treatment. The PSP was characterized with respect to mixing behavior, the BFR with respect to biofilm content and sorption of the pharmaceutical compounds. The short-term experiments were carried out for 55 h in the PSP and for 48 h in the BFR. The concentration of the pharmaceuticals was in the microgram per liter range in presence of readily biodegradable substances in the milligram per liter range. Therefore, a too short time period and too low concentration to promote adaption of the microorganisms were applied. Under the operating conditions applied the biodegradation of the lipid lowering agent clofibric acid and the analgesic agents ibuprofen and diclofenac in the oxic BFR resembled that in the PSP. Clofibric acid and diclofenac were not eliminated and reached a level of approximately 95% of their initial concentration, whereas the concentration of ibuprofen was decreased to approximately 40% in the PSP and to approximately 35% in the oxic BFR. Both systems showed, therefore, an inherent ability for ibuprofen biodegradation. Elimination in the anoxic BFR resulted in a decrease of the concentration of all three substances to values between 60 and 80% of their initial concentration. In contrast to the PSP acetone revealed as inhibitor in the BFR. In both systems acetone was not degraded in the short-term tests.

In the present study an analytical method was optimized for the determination of alpha-endosulfan, beta-endosulfan, endosulfan sulfate, endosulfan ether and endosulfan lactone in small volumes of environmental aqueous samples using solid-phase microextraction (SPME) and gas chromatography-electron capture detection (GC-ECD). A 100 micro m polydimethylsiloxane (PDMS) phase was used for the extraction. The limit of detection (LOD) for the analytes varied between 0.01 and 0.03 micro g L(-1) with a relative standard deviation of 3 to 11%. The influence of the ionic strength on the extraction efficiency was investigated for the individual compounds. alpha-Endosulfan, beta-endosulfan, endosulfan sulfate and endosulfan ether were extracted successfully without salt addition. The extraction efficiency of endosulfan lactone was improved with 30% NaCl content. A general decrease in extraction efficiency for alpha-endosulfan, beta-endosulfan, endosulfan sulfate and endosulfan ether with high NaCl content (20-30%) in the solution was observed due to glass surface adsorption. No effect of dissolved organic material (DOM) on the extraction efficiency was observed. The extraction coefficients changed between Log K=2.17 and 3.33. A sample from the Antarctic region was analyzed using the optimized GC-ECD/SPME method. To confirm the results obtained for the real sample a GC with a mass spectrometer (MS) was used. Endosulfan sulfate, the most toxic metabolite of endosulfan, was found in the sample at a concentration of 0.3 micro g L(-1).

Chlorination and ozonation experiments under conditions close to drinking water treatment were carried out with two different tap waters with low DOC content and water from a bog lake with high natural organic matter content. THM formation was low and in the range of 10 μg/L. Derivatization with dinitrophenylhydrazine and HPLC/tandem mass spectrometry were applied to measure carbonyl DBPs by precursor ion scans at m/z 163 for aldehydes and at m/z 182 for dicarbonyls. Formaldehyde, acetaldehyde, glyoxal, and methylglyoxal were formed by chlorination and ozonation. Ozonation produced the highest levels of carbonyls, in particular in the tap water samples. A strategy for structure suggestion and identification of unknown compounds on the basis of collision-induced dissociation (CID) mass spectra (MS) is given. The resulting structures are carbonyls with additional hydroxy and carboxy groups and serve for choice or synthesis of standard compounds for further identification. The possibilities and limits of compound identification are discussed.

To overcome the problem of non-specific interactions during the preparative fractionation of dissolved organic matter (DOM) for its combined chemical and biological characterization, the concept of standardized fractions (SFs) was developed. The concept is based on the calibration of the fractionation systems with suitable standards for the experimental definition of SFs, and the subsequent preparative fractionation of DOM samples according to the predefined SFs. Undesired non-specific interactions can thus be minimized experimentally. It was applied to the fractionation methods size exclusion chromatography (SEC) and multistage ultrafiltration (mst-UF). A brownwater sample and an effluent from a sewage treatment plant were fractionated. The two methods performed rather differently which was evidenced both by the polydispersity of the resulting fractions as well as sum parameter fractionation patterns. Consequently, the interpretation of data obtained from the chemical-physical as well as biological analysis must always consider the limitations and particularities of the fractionation method employed.

A method has been developed for quantitative determination of carbonyl disinfection by-products (DBP) from aqueous samples by derivatization with 2,4-dinitrophenylhydrazine combined with high-performance liquid chromatography (HPLC) and electrospray ionization (ESI) tandem mass spectrometry (MS-MS). The effect of excess of derivatization reagent and derivatization time, the effect of buffer and dry-gas temperature in the ESI process, and the effect of focus potential and collision energy in MS measurement are shown. Major fragment ions for compound identification on the basis of collision-induced dissociation (CID) mass spectra (MS) are given, as are common fragments for screening analyses by MS experiments such as the use of precursor ion scans. Detection limits in the microg x L(-1) range could be achieved by selected ion monitoring measurements without sample preconcentration. Solid-phase extraction improved the sensitivity by a factor of 25 to 250. The applicability of the method is illustrated by DBP analyses of samples from outdoor swimming pools after chlorination. Several carbonyl compounds, e.g. aldehydes, ketones, hydroxybenzaldehyde, and dicarbonyl compounds were identified.

The three metabolites hydroxyibuprofen (OH-Ibu), carboxyibuprofen (CA-Ibu), and carboxyhydratropic acid (CA-HA), also known from human metabolism of ibuprofen, could be identified in biodegradation experiments. Identification was based on EI mass spectra and comparison with literature data. Detection was performed by selective MS-MS measurements by GC-ion-trap MS and online methylation. Ibuprofen (Ibu), OH-Ibu, and CA-Ibu could be detected with a signal-to-noise ratio of 10:1 at a concentration of 2 nmol L(-1), CA-HA at 0.5 nmol L(-1). Degradation experiments in both biofilm reactors (BFR) and batch experiments with activated sludge (BAS) reveal OH-Ibu as the major metabolite under oxic conditions, and CA-HA under anoxic conditions. CA-Ibu was found under oxic and anoxic conditions almost only in the BAS. The metabolites together do not account for more than 10% of the initial concentration of Ibu.

Mass transfer and biological transformation phenomena in the capillary fringe were studied using phenol, salicylic acid, benzenesulfonic acid, and the iodinated X-ray contrast agent iomeprol as model organic compounds and the microorganism strain Pseudomonas fluorescens. Three experimental approaches were used: Batch experiments (uniform water saturation and transport by diffusion), in static columns (with a gradient of water saturation and advective transport in the capillaries) and in a flow-through cell (with a gradient of water saturation and transport by horizontal and vertical flow: 2-dimension flow-through microcosm). The reactors employed for the experiments were filled with quartz sand of defined particle size distribution (dp=200...600 μm, porosity e=0.42). Batch experiments showed that phenol and salicylic acid have a high, whereas benzenesulfonic acid and iomeprol have a quite low potential for biodegradation under aerobic conditions and in a matrix nearly close to water saturation. Batch experiments under anoxic conditions with nitrate as electron acceptor revealed that the biodegradation of the model compounds was lower than under aerobic conditions. Nevertheless, the experiments showed that the moisture content was also responsible for an optimized transport in the liquid phase of a porous medium. Biodegradation in the capillary fringe was found to be influenced by both the moisture content and availability of the dissolved substrate, as seen in static column experiments. The gas-liquid mass transfer of oxygen also played an important role for the biological activity. In static column experiments under aerobic conditions, the highest biodegradation was found in the capillary fringe (e.g. βt/β0 (phenol)=0 after t=6 d) relative to the zone below the water table and unsaturated zone. The highest biodegradation occurred in the flow-through cell experiment where the height of the capillary fringe was largest.

To find out more on the structure of humic substances (HS), isolated dissolved organic carbon (DOC) samples from a brown water lake and a wastewater effluent were fractionated and subjected to alkaline hydrolysis. UV/Vis and fluorescence spectroscopy, as well as size-exclusion chromatography with on-line detection of UV absorption, fluorescence and DOC concentration were used to investigate the structural changes caused by the hydrolysis reaction. Following hydrolysis, the fluorescence intensity increased considerably despite a decrease in the UV absorption. The UV absorption and the DOC data from the SEC experiments revealed a strong shift to smaller molecular sizes after hydrolysis. The spectra of the hydrolysed samples, as well as the size-exclusion chromatograms, were compared to spectra of hydroxybenzoic acids and hydroxycinnamic acids. From this comparison, it can be concluded that the hydrolysis products have a structure similar to these organic acids.

In the present study an analytical method was tested for the determination of selected pesticides and metabolites using solid-phase extraction (SPE) and gas chromatography ion-trap mass spectrometry (GC-MS). The extraction efficiency of C18, Isolut ENV+, and Lichrolut EN for SPE was compared for trifluralin, fenitrothion, endosulfan, propargite, 2,4-D, 3-methyl-4-nitrophenol, 2-(4-tert-butylphenoxy)cyclohexanol, endosulfan sulfate, and 2,4-dichlorophenol. Isolut ENV+ and C18 showed good results as sorbents and acetone as an elution solvent for SPE for the selected pesticides. Recoveries varied between 36% and 176% with a relative standard deviation of 2...18%. Because of coextracts from the SPE materials, recovery values higher than 100% were obtained for fenitrothion, endosulfan sulfate, and 2,4-D with C18 as well as for endosulfan sulfate and 3-methyl-4-nitrophenol with Isolut ENV+. A standard addition method was used to verify the occurrence of coextracts in the sample after SPE. Probleme und Losungen bei der Pestizidanalyse mittels Festphasenextraktion (SPE) und Gaschromatographie-Ion-Trap-Massenspektrometrie (GC-MS) In der vorliegenden Arbeit wurde eine analytische Methode zur Bestimmung von ausgewahlten Pestiziden und ihrer Metaboliten mittels Festphasenextraktion (SPE) und Gaschromatographie-Ion-Trap-Massenspektrometrie (GC-MS) getestet. Die Extraktionseffizienz der Festphasen C18, Isolut ENV+ und Lichrolut EN wurde fur Trifluralin, Fenitrothion, Endosulfan, Propargite, 2,4-D, 3-Methyl-4-nitrophenol, 2-(4-tert-Butylphenoxy)cyclohexanol, Endosulfansulfat und 2,4-Dichlorphenol verglichen. Isolut ENV+ und C18 zeigten gute Ergebnisse als Sorbentien mit Aceton als Elutionsmittel fur die SPE der ausgewahlten Pestizide. Die Wiederfindungsraten lagen zwischen 36% und 176% mit Standardabweichungen von 2...18%. Durch Matrixeffekte wurden Wiederfindungswerte uber 100% fur Fenitrothion, Endosulfansulfat und 2,4-D mit C18 und fur Endosulfansulfat und 3-Methyl-4-nitrophenol mit Isolut ENV+ erhalten. Eine Standardadditionsmethode wurde angewandt, um nach der SPE die Matrixeffekte in der Probe zu prufen.

An aquatic natural organic matter sample was concentrated by membrane filtration and fractionated using a size exclusion chromatography (SEC) system with a Superdex 75 column. Stability over time was investigated by reinjection of selected fractions. The reinjection yielded single peaks of a more or less Gaussian shape. From the peak shape of the individual fractions it was concluded that non-SEC mechanisms play an important role for the elution behavior. No significant change in the UV chromatograms could be detected over 5 weeks, suggesting a high stability of the fractions and only little or no alterations of the molecular weight distribution during that time period. The fractions were reexamined using a liquid chromatography system with online dissolved organic carbon detection (LCDOC system) with a TSK HW-50 (S) column. The average total recoveries of all fractions were 90 ± 4% for the Superdex system (calculated from UV-peak areas), and 102% and 105% for the spectral UV-absorbances (UVA) and dissolv...

Solid-phase extraction, on-line derivatization, and measurement by ion trap mass spectrometry (ITD-MS) were used to investigate the biological degradation of pharmaceutical residues (clofibric acid, ibuprofen, diclofenac). The results of the single steps of sample pretreatment and analytical determination are reported. MS/MS measurements were performed on an ITD-MS by selecting collision induced dissociation of the molecular ions (M + ) as parent ions to defined daughter ions. A pilot sewage plant and biofilm reactors operating under oxic and anoxic conditions were run as model systems with synthetic sewage water containing 10 to 50 mg/L dissolved organic carbon (DOC) and pharmaceuticals in concentrations of 10 μg/L. Clofibric acid displayed its persistent character in all cases. The pilot sewage plant and the oxic biofilm reactor showed comparable results for diclofenac and ibuprofen, which both were partly degraded. These results can explain the occurrence of these substances in sewage effluents and in the aquatic environment. A high degree of degradation was found especially for ibuprofen in the oxic biofilm reactor, which was attributed to adaptation of the biofilm to the residue. Two metabolites of ibuprofen could be identified on the basis of their mass spectra and comparison with literature data, viz. hydroxyibuprofen and carboxyibuprofen.

Size-exclusion experiments of alcohols, mono- and dicarboxylic acids, aromatic acids, and amino acids were conducted. Two columns with different gel packings (TSK HW 50 S and TSK G2000SW) were used to determine the influence of the gel core structure on the elution volume of organic substances. Neither for the polymer based gel nor for the silica based gel specific interactions, especially hydrophobic interactions, could be neglected. For both alcohols and monocarboxylic acids the elution volume increased with an increasing number of carbon atoms. It was found that aromatic compounds interacted strongly with both gels. Whereas alcohols were not affected by differences in ionic strength between sample and eluent, the elution volume of carboxylic acids was strongly influenced. In combination with a multidetector system (UV absorption, fluorescence, dissolved organic carbon, electrical conductivity) changes in the chromatographic behavior of these compounds due to differences in ionic strength between sample...

A method to separate and quantify two inorganic arsenic species As(III) and As(V) and two organic arsenic species, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), by HPLC-ICP/MS has been developed. The separation of arsenic species was achieved on the anionic exchange column IonPac AS11 (Dionex) with NaOH as mobile phase. The technique was successfully applied to analyze extracts of two contaminated soils, sampled at a former tannery site (soil 1) and a former paint production site (soil 2). The soils were extracted at pH values similar to the natural environment. Extractions were performed at different pH values with 0.3 M ammonium oxalate (pH = 3), milli-Q water (pH = 5.8), 0.3 M sodium carbonate (pH = 8) and 0.3 M sodium bicarbonate (pH = 11). No organically bound arsenic was found in the extracts. As(V) was the major component. Only up to 0.04% of the total arsenic contained in soil 1 were mobilized. The highest amount of extracted arsenic was found at the highest pH. In the milli-Q water extract of soil 1 As(III) and As(V) were found. High amounts of As(V) were found in the extracts of soil 2. Up to 20% of the total arsenic bound to soil 2 constituents were released. The results show that the mobilization of arsenic depended on the pH value of the extraction solution and the kind of extracted soil. Dramatic consequences have to be expected for pH changes in the environment especially in cases where soils contain high amounts of mobile arsenic.

A characterization method for AOX in surface water samples was developed and tested. The method involves fractionation using a hydrophobic C 18 resin and a weak anionic exchange resin and allows the fractionation of the AOX pool of surface water samples into four fractions: (1) hydrophilic acidic, (2) hydrophilic non-acidic, (3) hydrophobic acidic, and (4) hydrophobic non-acidic. The adsorption analysis was verified with AOX-relevant model compounds and was applied to characterize the AOX pool of a stream sample from the Moskva river (Russia). In addition to the fractionation analysis, size-exclusion chromatography was used to characterize the AOX pool of the sample studied. Hydrophilic acids made up the major fraction of the AOX pool (55 %). Among this fraction chlorinated high-molecular acids (humic substances) made up the main fraction (35%).

The method described uses the separation of As(III) and As(V) species in aqueous samples by means of the anion-exchange resin Amberlite IRA-93. The samples were acidified using acetic acid and passed through a glass column filled with pre-treated Amberlite IRA-93 resin. As(III) was poorly adsorbed on the anionic exchanger material, whereas As(V) was retained. The arsenic concentration was measured in the column effluent by graphite furnace AAS (GF-AAS). The retained As(V) was eluted from the column using 1 M NaOH. Prior to the determination of the As(V) concentration in the NaOH eluate, the eluate was passed through a glass column filled with a cation-exchange resin (Amberlite 200) to remove sodium ions and minimize the Na + interference with the AAS determination. After calibration the method was applied to the separation ofAs(III) and As(V) species in two aqueous extracts of arsenic contaminated soils. The results were compared with those obtained from an on-line separation and determination of As(III) and As(V) in the aqueous soil extracts using a state of the art HPLC-ICP-MS system.

Extracted aquatic fulvic acid samples (HO10FA) from a brown lake Hohloh in the Black Forest (Germany) were ozonated at two different ozone doses and then chlorinated. In connection with liquid chromatography and further detection systems (UV and DOC) on gel matrix, a combined system (gel chromatography) was used for a detailed characterization of ozonated and post-chlorinated fulvic acid samples. The gel chromatographic characterization showed a slight decrease in DOC (14%) and SAC254 (36%) at the end of 20 min ozonation whereas the low ozonation time (5 min) caused increased in DOC (6%) and SAC254 (56%).Extracted aquatic fulvic acid samples (HO10FA) from a brown lake Hohloh in the Black Forest (Germany) were ozonated at two different ozone doses and then chlorinated. In connection with liquid chromatography and further detection systems (UV and DOC) on gel matrix, a combined system (gel chromatograpy) was used for a detailed characterization of ozonated and post-chlorinated fulvic acid samples. The gel chromatographic characterization showed a slight decrease in DOC (14%) and SAC254 (36%) at the end of 20 min ozonation whereas the low ozonation time (5 min) caused increases in DOC (6%) and SAC254 (56%). German Academic Exchange Service London Deutscher Akademischer Austauschdienst Deutsche Forschungsgemeinschaft The authors thank the 32nd International Seminar(IS), German Academic Exchange Service (DAAD) and Deutsche Forschungsgemeinschaft (DFG, ROSIG) for financial support. We are grateful to Sebastian Hesse for experimental assistance.

The FA and HA fractions represent 20 to 50% of the DOC of the original samples, depending on the origin, and serve as reference materials. The original aqueous samples and the aqueous solutions of the reference materials were characterized with methods suited for measuring samples at natural concentrations. The DOC normalized values of the spectral absorbances (λ = 254 nm; λ = 436 nm) in the original water samples were highest for the brown water and brown coal water and lowest for the secondary effluents. The FA fractions were similar in the UV-absorbance with the exception of the low-absorbing groundwater FA, reflecting a low density of double bonds. The DOC-normalized proton capacity of the FA fractions (10 to 20 μmol/mg) was highest for the brown coal, brown water, and soil-derived samples and again lowest for the groundwater FA. The high values are due to a higher contribution of the weak acids of phenolic type. Specific data for copper complexation capacity (0.5 to 2.5 μmol/mg) went parallel to the proton capacity. The characterization of the FAs by gel chromatography with organic carbon detection revealed three major fractions. The refractory part at short retention time dominated in the brown water and soil-derived samples, whereas the fractions for the lower molecular mass acids at long retention times were dominant in the secondary effluent and the brown coal isolate. Comparison with UV-detected chromatograms revealed a strong decrease in the specific absorbance of the secondary effluent. Up to 3% of the total mass of the FAs could be identified as hydrolyzable amino acids with the highest yield in the sample from secondary effluent and the lowest one in the groundwater sample. The nitrogen content was always higher in the FAs compared to the HAs of the same origin. The application of gel chromatography fluorescence and fluorescence decay time distribution analysis turned out to be a useful tool to differentiate between the different fractions of NOM, the isolates obtained by different methods (e.g., XAD-8, membrane separation) and the fractions of the samples from different origin and age. This is of special value, for the information can also be obtained for samples with natural NOM concentrations, even though further investigations required for full understanding of the data. This work is part of a multi-disciplinary research program (ROSIG: Refraktare Organische Sauren in Gewassern), funded by the German Research Association (DFG).

NOM (natural organic matter) samples, isolated by reverse osmosis (RO), and nine NOM samples, concentrated by low-pressure, low-temperature evaporation (EVA) from various origin in Norway, were characterized by different methods. The methods included elemental content of the freeze-dried samples (C, H, N, and O), elemental content of the redissolved samples (DOC, Na, Ca, Cu, Fe, and Mn), specific spectral absorbance at λ = 254 nm (A(254 nm)/DOC) and at λ = 436 nm (A(436 nm)/DOC), UV/Vis-spectra, specific fluorescence (excitation and emission spectra), proton capacity, Cu-complexation capacity, and content of hydrolysable amino acids and carbohydrates. In addition, chromatographic characterization by gel chromatography and reversed-phase chromatography was done. Studies on adsorption and flocculation abilities and the formation of trihalomethanes (THM) and organic halogens adsorbable on activated carbon (AOX) upon chlorination were also investigated. Comparison of the results showed that the samples were different according to the origin of the sample, isolation procedure, and time of sampling. The differences are not the same for all parameters used. Standardized procedures have to be applied to redissolve the organic material in water in order to compare data. For the samples investigated, it was shown that parameters like elemental analysis (H/C ratio), the specific spectral absorption in the UV range, proton capacity, complexation capacity and anionic particle charge, amount of hydrolysable amino acids and carbohydrates, adsorption behaviour on activated carbon, and the THM-FP are sensitive parameters to show differences concerning origin and isolation procedure.

In recent years, the ozone treatment technique has been discussed for remediation of contaminated sites. In this paper, data on the effects of ozonation of soil organic matter in ground and pore waters are presented. An aqueous soil extract was ozonated in a stirred tank reactor and characterized by size-exclusion chromatography with online UV and dissolved organic carbon detection. Additionally, degradation experiments were carried out with these extracts in a bacteria regrowth measurement system. After ozonation, a decrease of the humic acid fraction and a reduction of its average molecular size could be recognized. In contrast to this, there was an increase of the building block fraction and the low molecular acid fraction. These two fractions were readily degradable by microorganisms. Therefore, the bacteria regrowth increased with ozonation time. As a result of this, a fast and high regrowth of bacteria can be expected after the ozone remediation technique has been applied. The UV absorbance of extracts at a wavelength of 254 nm showed no significant changes before and after biological degradation. It can be supposed that the microorganisms were not able to degrade chromophoric groups absorbing at a wavelength of 254 nm.

Groundwater samples from a former gas plant site were investigated by headspace GC/MS and general parameters with regard to organic pollution. The contamination plume was distinguished from background with GC/MS headspace and dissolved organic carbon analyses. Headspace GC/MS analyses of these samples revealed the presence of several aromatic and heterocyclic compounds typical to coal tar leachates. Selected ion monitoring GC/MS was used to establish the relative contamination level of seven selected polycyclic aromatic hydrocarbons (PAH) from 9 sampling wells. Three wells showed a high contamination level and therefore, they could be attributed to the vicinity of contamination sources. Well samples downgradient from the pollution source showed decreasing contamination levels for all compounds except acenaphthene.

A commercial particle beam interface coupled to a single quadrupole mass spectrometer has been used for a nontarget screening of highly contaminated water samples from a former gas plant. A liquid chromatographic system has been used to separate hydrophilic compounds with a high percentage water gradient without any loss of efficiency in the MS interface. The ground water showed a high pollution burden in the total ion current chromatogram. Full scan EI mass spectra have been obtained for identification of unknown compounds which could be assigned to oxidation products of heterocyclic aromatic compounds, some known constituents of coal tar. The identification of 6(5H)-phenanthridinone has been confirmed by comparison with a corresponding standard. The difficulties of an unequivocal identification of isoquinolinone and methyl derivatives of quinolinone based on their EI mass spectra are discussed.

Two liquid chromatography-particle beam mass spectrometry (LC-PBMS) systems have been used for analysis of polycyclic aromatic hydrocarbon metabolites in water samples from a biological decomposition model experiment. The results were compared with those obtained by classical gas chromatography-mass spectrometry. Evaluation of spectral data indicated the presence of six main metabolites; 1H,3H-naphtho [1,8-cd]pyran-1,3-dione, 1-(hydroxymethyl)naphthalene, and 1,2-acenaphthenedione were identified by use of standard substances and spiking experiments. Enrichment of the investigated water samples with online pre-column (C18) concentration, freeze-drying, and solvent extraction led to similar results with only slight differences. The application of microbore separation columns proved to be a promising tool in particle beam LC-MS measurements.

The adsorption behaviour of humic substances on activated carbon was different for samples of different origin. Humic substances isolated from bog lakes or from aqueous soil solutions are less adsorbable than those from rivers, groundwater, or samples from landfill leachates. The adsorption behaviour was determined by different physical and chemical parameters. The experimental data could be described by model calculations based on Freudlich equations for two fictive components of the total dissolved organic carbon. The nominal molecular weight distribution of humic substances from bog lakes and soil solution showed relatively high values. In addition, these substances had pronounced aromatic structures. This goes along with a relatively weak adsorption on activated carbon. There was no clear correlation concerning the hydrophilic character of the humic substances and their acidic character (proton capacity). Humic substances isolated from river water, groundwater, and landfill leachates showed lower nominal molecular weight and lower UV-absorbance. They had a higher aliphatic character and were more readily adsorbed on activated carbon than the other samples. The findings are of technical importance for water treatment.

Es wird eine Methode zur enzymatischen Hydrolyse von Huminstoffen vorgestellt. Das dafur eingesetzte Enzym spaltet spezifisch Aminosauren ab, die nach Vorsaulenderivatisierung und HPLC-Trennung mit einem Fluoreszenzdetektor erfast werden. Die ermittelten Aminosauregehalte von Huminstoffen unterschiedlicher Herkunft werden verglichen und den Ergebnissen nach Anwendung der klassischen Saurehydrolyse gegenubergestellt. Grenzen und Moglichkeiten der beschriebenen enzymatischen Methode zur Charakterisierung von Huminstoffen ergeben sich durch den Vergleich beider Hydrolysemethoden und durch Berucksichtigung von Effekten wie Enzymhemmung und Enzymspefizitat. A method is described for the specific hydrolysis of amino acids from humic substances by using the proteolytic enzyme “Pronase E”. The amino acids are analyzed by a fluorescence detector after precolumn derivatization and HPLC-separation. The pattern and the concentration of amino acids after the enzymatic hydrolysis are set up for humic substances of different origin. Due to the results the enzymatic hydrolysis is suitable for the characterization of humic substances with a nitrogen content higher than 3%. As shown in a kinetic study of the hydrolysis of a fulvic acid the influence of humic substances on the enzyme activity increases in case of lower nitrogen content. Due to the specificity of the proteolytic enzyme the operationally defined method is limited as shown by a protein of a known amino acid content. The amino acids leucine, valine, tyrosine and histidine are released to the highest extent. The determined total extent for the hydrolysis of Insulin B is 26.34% and for Casein 38.37%. By comparison of the enzymatic hydrolysis with the classic acid hydrolysis the advantages of the biochemical method are the simple experimental handling and the mild reaction conditions. Amino acids which are very unstable like glutamine and asparagine can only be analyzed by the enzymatic hydrolysis.

The rapid development of nanotechnology and the related production and application of nanosized materials such as engineered nanoparticles (ENP) inevitably lead to the emission of these products into environmental systems. So far, little is known about the occurrence and the behaviour of ENP in environmental aquatic systems. In this contribution, the influence of natural organic matter (NOM) and ionic strength on the stability and the interactions of silver nanoparticles (n-Ag) in aqueous suspensions was investigated using UV-vis spectroscopy and asymmetrical flow field-flow fractionation (AF⁴) coupled with UV-vis detection and mass spectrometry (ICP-MS). n-Ag particles were synthesized by chemical reduction of AgNO₃ with NaBH₄ in the liquid phase at different NOM concentrations. It could be observed that the destabilization effect of increasing ionic strength on n-Ag suspensions was significantly decreased in the presence of NOM, leading to a more stable n-Ag particle suspension. The results indicate that this behaviour is due to the adsorption of NOM molecules onto the surface of n-Ag particles ("coating") and the resulting steric stabilization of the particle suspension. The application of AF⁴ coupled with highly sensitive detectors turned out to be a powerful method to follow the aggregation of n-Ag particle suspensions at different physical-chemical conditions and to get meaningful information on their chemical composition and particle size distributions. The method described will also open the door to obtain reliable data on the occurrence and the behaviour of other ENP in environmental aquatic systems.

In investigations concerning the photocatalytic degradation by TiO2 usually filter discs with a pore size of 0.22 μm and 0.45 μm are used for the removal of photocatalyst particles in aqueous suspensions. In this study the effective rejection of suspended particles by microfiltration in different types of membrane modules and with different membrane materials was investigated. Furthermore, Powdered Activated Carbon (PAC), which can be used to gain an increase in photocatalytic degradation rates, was investigated concerning its influence on the membrane performance. It is shown that by membrane filtration with a pore size above 0.1 μm, irrespective of the experimental conditions, no complete removal can be achieved. However, UV irradiation was found to improve the removal efficiency for all types of tested membrane materials. The addition of PAC also led to a higher performance of membrane filtration with regard to particle rejection. In long-term experiments with a hollow fibre membrane module in the presence of PAC a five-fold decrease of TiO2 particles in the permeate could be proven. Besides, it was shown that added PAC can shield the membrane regarding the abrasivity of TiO2, which could otherwise lead to the destruction of the membrane. Therewith PAC exhibits another crucial advantage besides its synergetic effect in photodegradation.

Organotin compounds belong to the widespread micropollutants in the aquatic environment. They can be analysed by different analytical procedures. The recently available atomic emission detector (AED) in combination with gas chromatography is a promising tool for this task. Identification and quantification of organotin compounds in water and sediment can be achieved in ranges of ng/l and μg/l, respectively. The quality criteria for the values obtained depend strongly on the matrices and on the tin-species investigated. In general recovery rates are higher for aqueous samples than for sediments. From model experiments it can be deduced that humic substances play an important role in adsorption of tin organyles in sediment. In addition to the known fact that activated carbon readily eliminates tributyltin from aqueous solutions, the kinetics of recovery experiments show that part of the organotin compounds are irreversibly adsorbed on solid phase.

Liquid chromatography (LC) in the high and medium pressure mode in association with sensitive detection systems [UV-vis, diode array detector (DAD), fluorescence, dissolved organic carbon (DOC)] is used for the characterization of dissolved organic matter in aqueous samples. Even though the chromatographic mechanisms for the fractionation of humic-type organic substances are not fully known, the use of different columns (gel, C-18 phases, etc.) adds significantly to the understanding of the functionality of the organics. The chromatograms show that there are larger differences between the isolated fulvic acids (FAs) and the organics in unaltered water samples than between FAs from different origin but isolated using the same method. The influence of the isolation procedure is demonstrated on soil extracts. For the first time an on-line DOC detection system is used to trace the liquid chromatogram of a tap water sample.

An immunolabelling procedure was developed to detect bound pesticide residues in soil using atrazine as an example. Polyclonal antibodies directed against atrazine were raised in rabbits. Antigen-binding fragments (Fab) were prepared and coupled to the fluorescent stain Rose Bengal B. The dye conjugate produced a fluorescence signal which was related to the amount of atrazine found in native soil samples. Preincubation with unlabelled immunoglobulines (IgG) from preimmune sera proved to be essential for blocking unspecific binding of the antibodies which varied greatly between different samples of soil material. Labelled antibodies, whose specific binding sites had been blocked by free atrazine, were used as controls. Strong unspecific labelling, which also could be suppressed with IgG from preimmune sera, was observed in a soil under a barn. Changes due to the permanent dryness and the lack of aeration are discussed as possible causes. Immunmarkierung von Atrazinruckstanden im Boden Zur Erfassung gebundener Ruckstande von Pflanzenbehandlungsmitteln im Boden wurde am Beispiel des Atrazins ein Immunmarkierungsverfahren entwickelt. Polyklonale Antikorper gegen Atrazin wurden in Kaninchen gewonnen. Daran schlos sich die Kopplung der antigenbindenden Fragmente (Fab) an den Fluoreszenzfarbstoff Bengalrosa an. Das Farbstoffkonjugat lieferte ein Fluoreszenzsignal, das bei nativen Boden mit der Menge an gebundenem Atrazin korreliert war. Zur Blockierung unspezifischer Antikorperbindungen, die zwischen den einzelnen Bodenproben stark schwankten, erwies sich eine Vorinkubation mit unmarkierten Praimmunseren als essentiell. Als Nullkontrollen dienten markierte Antikorper, deren spezifische Bindungsstellen durch freies Atrazin blokkiert waren. Starke unspezifische Bindungen, die ebenfalls durch Inkubation mit Praimmunseren beseitigt werden konnten, wurden bei einem unter einer Scheune entnommenen Boden beobachtet. Als Ursache werden Veranderungen durch permanente Trockenheit und Luftabschlus diskutiert.

Extracellular polymeric substances were extracted from the bacterial strain Pseudomonas putida and the fungal species Aureobasidium pullulans using three different methods (formaldehyde-NaOH, ethylenediaminetetraacetic acid (EDTA) and cation-exchange-resin). The composition of the extracellular polymeric substances (EPS) was analysed by biochemical and high-resolution solid state 13C nuclear magnetic resonance (NMR) spectroscopic methods. The EPS yield was strongly dependent on the extraction method, with the formaldehyde-NaOH method showing the best extraction efficiency. The NMR method revealed that when using the EDTA extraction method, about 40% of the EDTA accumulated in the EPS and that was responsible for the apparent high extraction yields. EPS protein content determined by the NMR method was up to 30% higher than the protein content determined using the biochemical (Lowry) method for P. putida and for A. pullulans. The average protein carbon content determined by the NMR method was approximately 70% of the total carbon content. NMR results could be supported by elemental analysis, which showed a high nitrogen content (approximately 10%) in the EPS. The carbohydrate carbon content detected with both methods in the cell aggregates and the EPS was approximately 20% in each. In this study, quantitative 13C cross-polarisation magic angle spinning NMR spectroscopy was conducted on unlabeled cell strains, and EPS and could be used to quantify protein and carbohydrate of different samples.

Potentiostatic-controlled electrochemical reduction of iomeprol was used to deiodinate iomeprol (IMP), a representative of the iodinated X-ray contrast media. The reduction process was followed by product analysis with liquid chromatography-electrospray ionization-tandem mass spectrometry and ion chromatography-inductively coupled plasma-mass spectrometry. The identification is mainly based on the interpretation of the mass fragmentation. The product analysis showed a rather selective deiodination process with the successive occurrence of IMP-I, IMP-2I, IMP-3I, and a transformation product (TP), respectively. The TP was formed from IMP-3I by a further cleavage of an amide bond and release of a (C = O)CHOH group from the side chain of IMP. The iodine mass balance on the basis of IMP and iodide showed a gap of about 26% at the beginning of the electrolysis process which could be completely closed by taking the intermediates IMP-I and IMP-2I into consideration. This means that the major intermediates and the TPs were considered and that the reduction process is a rather selective one to remove organically bound iodine from X-ray contrast media. An attractive application area would be the electrochemical deiodination of X-ray contrast media in urine of patients or hospital effluents.

A very fast determination of sulphate in ground and drinking water by inductively coupled plasma emission spectrometry (ICP/OES) is described. The 182.037 nm line was selected for the measurement of the total sulphur content, because this line is not disturbed by calcium, one of the main components in natural waters. The limit of determination (0.5 mg/l SO 4 2− ) is low enough for most aquatic samples. With a two point calibration the linear working range is between 0.5 and 100 mg/l SO 4 2− .

The availability of epifluorescence microscopy opens the door for the visualization of biofilm flocs via the fluorescence staining technique. However, one of the main problems in the application of the method is a missing standardized protocol for sample preparation. In this study, different pre-treatment methods for the simultaneous staining of different sludge flocs components e.g. extracellular polymeric substances (EPS) and microorganisms (MO) were compared. A method was chosen, which remains the shape of sludge flocs from a municipal wastewater treatment plant and allows to stain major parts of the flocs thoroughly: For this the surrounding wastewater was removed by centrifugation. Then the flocs were resuspended in sterile tap water, immobilized by drying on a diagnostic slide and fixated with formaldehyde. The staining of the different compounds was performed with tetramethylrhodamine isothiocyanate-labeled lectin Concanavalin A (TRITC-Con A; glycoconjugates), fluoresceinisothiocyanate isomer I (FITC; amino groups) and 4,6-diamidino-2-phenylindoldihydrochloride (DAPI; nucleic acids). This staining method was successfully applied for protein- and carbohydrate-quantification using gelatin mixtures of dextran and bovine serum albumin (BSA). The pre-treatment and staining methods were appropriate to compare the composition of different biofilm flocs such as nitrifying activated sludge from a municipal wastewater treatment plant and a pure culture of the bacterial strain Pseudomonas putida (ATCC 17514) as revealed by the results of conventional analytical methods.