Publications by authors named "Torsten C Schmidt"

198 Publications

Development of a multidimensional online method for the characterization and quantification of monoclonal antibodies using immobilized flow-through enzyme reactors.

Anal Bioanal Chem 2021 Nov 9;413(28):7119-7128. Epub 2021 Oct 9.

Faculty of Chemistry, Instrumental Analytical Chemistry, University Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany.

Complete characterization and quantification of monoclonal antibodies often rely on enzymatic digestion with trypsin. In order to accelerate and automate this frequently performed sample preparation step, immobilized enzyme reactors (IMER) compatible with standard HPLC systems were used. This allows an automated online approach in all analytical laboratories. We were able to demonstrate that the required digestion time for the model monoclonal antibody rituximab could be reduced to 20 min. Nevertheless, a previous denaturation of the protein is required, which also needs 20 min. Recoveries were determined at various concentrations and were 100% ± 1% at 100 ng on column, 96% ± 7% at 250 ng on column and 98% ± 2% at 450 ng on column. Despite these good recoveries, complete digestion was not achieved, resulting in a poorer limit of quantification. This is 50 ng on column under optimized IMER conditions, whereas an offline digest on the same system achieved 0.3 ng on column. Furthermore, our work revealed that TRIS buffers, when used with an IMER system, led to alteration of the peptides and induced modifications in the peptides. Therefore, the addition of TRIS should be avoided when working at elevated temperatures of about 60 °C. Nevertheless, our results have shown that the recovery is not significantly influenced whether TRIS is used or not (recovery: 96 ± 7% with TRIS vs. 100 ± 9% without TRIS).
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http://dx.doi.org/10.1007/s00216-021-03683-zDOI Listing
November 2021

Non-targeted LC-MS and CE-MS for biomarker discovery in bioreactors: Influence of separation, mass spectrometry and data processing tools.

Sci Total Environ 2021 Dec 17;798:149012. Epub 2021 Jul 17.

Department of Chemistry, Aalen University, D-73430 Aalen, Germany. Electronic address:

Liquid separation coupled to mass spectrometry is often used for non-targeted analyses in various fields, such as metabolomics. However, the combination of non-standardized methods, various mass spectrometers (MS) and processing tools for data evaluation affect biomarker discovery potentially. Here, we present a comprehensive study of these factors based on non-targeted liquid chromatography coupled to time-of-flight (TOF) and Orbitrap MS and capillary zone electrophoresis to Orbitrap analyses of the same bioreactor samples, describing the correlation of its gas yield with changing feature signal intensity. The three datasets were processed with MZmine 2 and XCMS online and subsequential Partial Least Square Regression (PLSR) with Variable Importance in Projection (VIP) ranking for feature prioritization. The six feature tables were compared to evaluate their overlap of shared features and the influence of the processing software and MS instrument on the VIP values and fold changes. The overlaps, defined as a fraction of one feature table found in the comparative table, were from 27% to 57% for the comparison of MZmine and XCMS and from 15% to 50% between Orbitrap and TOF data sets, respectively. Considering the most relevant features only (VIP >1.5), the overlaps were increased significantly in all cases from 26% to 95%. For the same data set, both VIP values and fold changes were well correlated, however, varied significantly between TOF and Orbitrap. CE-MS showed higher total feature numbers compared to LC-MS, most likely due to its more appropriate selectivity, different sample preparation, and/or the sensitive nano-ESI interface. Since only less than 10% of MS/MS data overlapped, CE-MS provided complementary information to LC-MS. Overall, our systematic study proves the benefits of using different separation techniques and processing tools but also indicates a significant influence of mass spectrometry on comprehensive biomarker discovery.
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http://dx.doi.org/10.1016/j.scitotenv.2021.149012DOI Listing
December 2021

Potentially toxic elements leachates from cigarette butts into different types of water: A threat for aquatic environments and ecosystems?

Environ Res 2021 11 17;202:111706. Epub 2021 Jul 17.

Department of Environmental Health Engineering, Faculty of Health and Nutrition, Bushehr University of Medical Sciences, Bushehr, Iran.

Trillions of cigarette butts (CBs) are released into the environment and the leached potentially toxic elements (PTEs) from CBs may contaminate the environments. In this study, the leaching of PTEs including both heavy metals and metalloids (metal(loid)s) from CBs into deionized water (DW), tap water (TW), and seawater (SW) was checked during the different contact times (from 60 min to 60 days). According to the results, PTEs were leached from CBs into different water samples. However, there were no significant differences between leachates in DW and TW samples (p > 0.05). The results of the distribution coefficient indicated the high tendency of most PTEs to enter the liquid phase. The levels of leached PTEs into DW and TW exceeded the standards of surface freshwater to maintain aquatic life. Although the maximum level of leached metal(loid)s into DW, TW, and SW occurred at different times, for each type of water sample no significant differences were found among the levels of most PTEs at various contact times. Based on the results, the levels of leached metal(loid)s from CBs in seawater peak soon after being released into the water, while for the freshwater, they occur after some days. This phenomenon could possibly have short-term and long-term effects on marine and freshwater organisms, respectively. Due to the ability of the dissolved PTEs to integrate into the aquatic/terrestrial food web and threaten human health, some control measures regarding the disposal of CBs are necessary.
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http://dx.doi.org/10.1016/j.envres.2021.111706DOI Listing
November 2021

Target, suspect and non-target screening analysis from wastewater treatment plant effluents to drinking water using collision cross section values as additional identification criterion.

Anal Bioanal Chem 2021 Mar 25. Epub 2021 Mar 25.

IWW Water Centre, Moritzstraße 26, 45476, Muelheim an der Ruhr, Germany.

The anthropogenic entry of organic micropollutants into the aquatic environment leads to a potential risk for drinking water resources and the drinking water itself. Therefore, sensitive screening analysis methods are needed to monitor the raw and drinking water quality continuously. Non-target screening analysis has been shown to allow for a more comprehensive investigation of drinking water processes compared to target analysis alone. However, non-target screening is challenging due to the many features that can be detected. Thus, data processing techniques to reduce the high number of features are necessary, and prioritization techniques are important to find the features of interest for identification, as identification of unknown substances is challenging as well. In this study, a drinking water production process, where drinking water is supplied by a water reservoir, was investigated. Since the water reservoir provides surface water, which is anthropogenically influenced by wastewater treatment plant (WWTP) effluents, substances originating from WWTP effluents and reaching the drinking water were investigated, because this indicates that they cannot be removed by the drinking water production process. For this purpose, ultra-performance liquid chromatography coupled with an ion-mobility high-resolution mass spectrometer (UPLC-IM-HRMS) was used in a combined approach including target, suspect and non-target screening analysis to identify known and unknown substances. Additionally, the role of ion-mobility-derived collision cross sections (CCS) in identification is discussed. To that end, six samples (two WWTP effluent samples, a surface water sample that received the effluents, a raw water sample from a downstream water reservoir, a process sample and the drinking water) were analyzed. Positive findings for a total of 60 substances in at least one sample were obtained through quantitative screening. Sixty-five percent (15 out of 23) of the identified substances in the drinking water sample were pharmaceuticals and transformation products of pharmaceuticals. Using suspect screening, further 33 substances were tentatively identified in one or more samples, where for 19 of these substances, CCS values could be compared with CCS values from the literature, which supported the tentative identification. Eight substances were identified by reference standards. In the non-target screening, a total of ten features detected in all six samples were prioritized, whereby metoprolol acid/atenolol acid (a transformation product of the two β-blockers metoprolol and atenolol) and 1,3-benzothiazol-2-sulfonic acid (a transformation product of the vulcanization accelerator 2-mercaptobenzothiazole) were identified with reference standards. Overall, this study demonstrates the added value of a comprehensive water monitoring approach based on UPLC-IM-HRMS analysis.
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http://dx.doi.org/10.1007/s00216-021-03263-1DOI Listing
March 2021

Quality control of cytostatic drug preparations-comparison of workflow and performance of Raman/UV and high-performance liquid chromatography coupled with diode array detection (HPLC-DAD).

Anal Bioanal Chem 2021 Apr 23;413(9):2587-2596. Epub 2021 Feb 23.

Institut für Energie und Umwelttechnik e. V. (IUTA, Institute of Energy and Environmental Technology), Bliersheimer Str. 58-60, 47229, Duisburg, Germany.

The drugs used for treatment during chemotherapy are manufactured individually for each patient in specialised pharmacies. Thorough quality control to confirm the identity of the delivered active pharmaceutical ingredient and the final concentration of the prepared application solution is not standardized yet except for optical or gravimetric testing. However, solution stability problems, counterfeit drugs, and erroneous or deliberate underdosage may occur and negatively influence the quality of the product and could cause severe health risks for the patient. To take a step towards analytical quality control, an on-site analytical instrument using Raman and UV absorption spectroscopy was employed and the results were compared to high-performance liquid chromatography coupled to diode array detection. Within the scope of the technology evaluation, the uncertainty of measurement was determined for the analysis of the five frequently used cytostatic drugs 5-fluorouracil, cyclophosphamide, gemcitabine, irinotecan and paclitaxel. The Raman/UV technique (2.0-3.2% uncertainty of measurement; level of confidence: 95%) achieves a combined uncertainty of measurement comparable to HPLC-DAD (1.7-3.2% uncertainty of measurement; level of confidence: 95%) for the substances 5-fluorouracil, cyclophosphamide and gemcitabine. However, the uncertainty of measurement for the substances irinotecan and paclitaxel is three times higher when the Raman/UV technique is used. This is due to the fact that the Raman/UV technique analyses the undiluted sample; therefore, the sample has a higher viscosity and tendency to foam. Out of 136 patient-specific preparations analysed within this study, 96% had a deviation of less than 10% from the target content.
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http://dx.doi.org/10.1007/s00216-021-03223-9DOI Listing
April 2021

Effect-based evaluation of ozone treatment for removal of micropollutants and their transformation products in waste water.

J Toxicol Environ Health A 2021 05 24;84(10):418-439. Epub 2021 Feb 24.

Centre for Water and Environmental Research (ZWU), University of Duisburg-Essen, Essen, Germany.

The aim of this interdisciplinary research project in North Rhine-Westphalia (NRW), Germany, entitled "Elimination of pharmaceuticals and organic micropollutants from waste water" involved the conception of cost-effective and innovative waste-water cleaning methods. In this project assays, assays and chemical analyses were performed on three municipal waste-water treatment plants (WWTP). This publication focuses on the study of the bioassays. Cytotoxic, estrogenic, genotoxic and mutagenic effects of the original as well as enriched water samples were monitored before and after wastewater treatment steps using MTT and PAN I, ER Calux and A-YES, micronucleus and Comet assays as well as AMES test. In most cases, the measured effects were reduced after ozonation, but in general, the biological response depended upon the water composition of the WWTP, in particular on the formed by-products and concentration of micropollutants. In order to be able to assess the genotoxic and/or mutagenic potential of waste-water samples using bioassays like Ames test, Comet assay or micronucleus test an enrichment of the water sample via solid-phase extraction is recommended. This is in agreement with previous studies such as the "ToxBox"-Project of the Environmental Agency in Germany.
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http://dx.doi.org/10.1080/15287394.2021.1881854DOI Listing
May 2021

The influence of injection volume on efficiency of microbore liquid chromatography columns for gradient and isocratic elution.

J Chromatogr A 2021 Mar 4;1641:461965. Epub 2021 Feb 4.

Institut für Energie- und Umwelttechnik e. V., IUTA (Institute of Energy and Environmental Technology), Bliersheimer Str. 58-60, 47229 Duisburg, Germany. Electronic address:

The injection volume and the associated column volume overload is one of the most common issues in miniaturized chromatography. The injection volume should not exceed 10% of the effective column volume. A further reduction of the injection volume leads to an increase in chromatographic efficiency. However, the signal intensity must be above a certain threshold to generate a chromatographic peak that can be detected. Therefore, the injection volume has to be optimized to reach the ideal balance between chromatographic efficiency and sensitivity. This study examined the general influence of the injection volume for both isocratic and gradient elution, depending on the retention factor and peak standard deviation. For this purpose, substances of different polarity were selected to represent a broad elution spectrum. Besides the model analyte naphthalene, these were mainly pharmaceuticals. For all measurements a microbore column with an ID of 300 µm and packed with 1.9 μm fully porous particles was used. For isocratic elution, the injection volume was varied between 4 and 16% of the effective column volume. The retention factors were adjusted between 2 and 10. For gradient elution, the injection volume was varied between 4 and 160% of the effective column volume. The observed effects were further investigated using the gradient kinetic plot theory. In isocratic elution, a loss in plate height up to 50% was observed for components that elute near the void time. A significant reduction of the chromatographic efficiency was noticed up to a retention factor of 4. In gradient elution, a reduction in peak capacity could only be observed if the injection volume exceeded 40% of the effective column volume. For some substances, only a slight loss in peak capacity was noticed even with a volume overload of 160%.
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http://dx.doi.org/10.1016/j.chroma.2021.461965DOI Listing
March 2021

Environmental fate of cigarette butts and their toxicity in aquatic organisms: A comprehensive systematic review.

Environ Res 2021 04 16;195:110881. Epub 2021 Feb 16.

Medical Library and Information Science Department, Bushehr University of Medical Sciences, Bushehr, Iran.

Cigarette butts (CBs) are the most frequently littered pieces of environmental wastes which are released both directly and indirectly into the environment and finally may reach aquatic environments and contaminate aquatic biomes. However, to date, there is no comprehensive review on the extent and magnitude of the potential effects of CBs on aquatic organisms. Hence, a systematic review of published studies was conducted in this paper to survey the fate of CBs in the aquatic environments and also the impacts of exposure to CBs on survival, growth, and reproduction of aquatic organisms. The gathered data showed that the leachates of CBs in the aquatic environment could extremely be toxic for various organisms and increasing the exposure time, increases the mortality rate. In addition, smoked filtered CBs with tobacco remnants have higher mortality rate compared to unsmoked filtered butts (USFs) for Hymenochirus curtipes, Clarias gariepinus, tidepool snails, Atherinops affinis and Pimephales promelas. The fate of CBs in the aquatic environments is affected by various factors, and prior to sinking they are floated for a long time (long distance). Hence, CBs and their associated toxic chemicals might be ingested by diverse aquatic organisms. However, further studies are necessary to understand the exact toxicity of CBs on different freshwater and marine organisms and also their fate in the aquatic media. The results of this review showed the essentiality of regulations to prevent the release of chemical and toxic compounds into the aquatic environments.
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http://dx.doi.org/10.1016/j.envres.2021.110881DOI Listing
April 2021

Heteroternary cucurbit[8]uril complexes as supramolecular scaffolds for self-assembled bifunctional photoredoxcatalysts.

Chem Commun (Camb) 2021 Mar 19;57(23):2887-2890. Epub 2021 Feb 19.

Faculty of Chemistry, Organic Chemistry and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitätsstrasse. 7, Essen 45141, Germany.

The self-assembly of bifunctional photoredoxcatalysts is reported. A series of photosensitizers and water-reducing catalysts were functionalized with viologen- and naphthol-units, respectively. Subsequent formation of the heteroternary cucurbit[8]uril-viologen-naphthol complexes was used for the constitution of bifunctional photoredoxcatalysts for hydrogen generation.
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http://dx.doi.org/10.1039/d0cc08025jDOI Listing
March 2021

Eye fluke infection changes diet composition in juvenile European perch (Perca fluviatilis).

Sci Rep 2021 02 9;11(1):3440. Epub 2021 Feb 9.

Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12589, Berlin, Germany.

Intraspecific diet specialization, usually driven by resource availability, competition and predation, is common in natural populations. However, the role of parasites on diet specialization of their hosts has rarely been studied. Eye flukes can impair vision ability of their hosts and have been associated with alterations of fish feeding behavior. Here it was assessed whether European perch (Perca fluviatilis) alter their diet composition as a consequence of infection with eye flukes. Young-of-the-year (YOY) perch from temperate Lake Müggelsee (Berlin, Germany) were sampled in two years, eye flukes counted and fish diet was evaluated using both stomach content and stable isotope analyses. Perch diet was dominated by zooplankton and benthic macroinvertebrates. Both methods indicated that with increasing eye fluke infection intensity fish had a more selective diet, feeding mainly on the benthic macroinvertebrate Dikerogammarus villosus, while less intensively infected fish appeared to be generalist feeders showing no preference for any particular prey type. Our results show that infection with eye flukes can indirectly affect interaction of the host with lower trophic levels by altering the diet composition and highlight the underestimated role of parasites in food web studies.
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http://dx.doi.org/10.1038/s41598-021-81568-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7873217PMC
February 2021

High-performance thin-layer chromatography in combination with a yeast-based multi-effect bioassay to determine endocrine effects in environmental samples.

Anal Bioanal Chem 2021 Feb 3;413(5):1321-1335. Epub 2021 Jan 3.

Institut für Energie- und Umwelttechnik e. V. (IUTA, Institute of Energy and Environmental Technology), Bliersheimer Str. 58 - 60, 47229, Duisburg, Germany.

Effect-directed analysis (EDA) that combines effect-based methods (EBMs) with high-performance thin-layer chromatography (HPTLC) is a useful technique for spatial, temporal, and process-related effect evaluation and may provide a link between effect testing and responsible substance identification. In this study, a yeast multi endocrine-effect screen (YMEES) for the detection of endocrine effects is combined with HPTLC. Simultaneous detection of estrogenic, androgenic, and gestagenic effects on the HPTLC plate is achieved by mixing different genetically modified Arxula adeninivorans yeast strains, which contain either the human estrogen, androgen, or progesterone receptor. Depending on the yeast strain, different fluorescent proteins are formed when an appropriate substance binds to the specific hormone receptor. This allows to measure hormonal effects at different wavelengths. Two yeast cell application approaches, immersion and spraying, are compared. The sensitivity and reproducibility of the method are shown by dose-response investigations for reference compounds. The spraying approach indicated similar sensitivities and higher precisions for the tested hormones compared to immersion. The ECs for estrone (E1), 17β-estradiol (E2), 17α-ethinylestradiol (EE2), 5α-dihydrotestosterone (DHT), and progesterone (P4) were 95, 1.4, 10, 7.4, and 15 pg/spot, respectively. Recovery rates of E1, E2, EE2, DHT, and P4 between 88 and 120% show the usability of the general method in combination with sample enrichment by solid phase extraction (SPE). The simultaneous detection of estrogenic, androgenic, and gestagenic effects in wastewater and surface water samples demonstrates the successful application of the YMEES in such matrices. This promising method allows us to identify more than one endocrine effect on the same HPTLC plate, which saves time and material. The method could be used for comparison, evaluation, and monitoring of different river sites and wastewater treatment steps and should be tested in further studies.
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http://dx.doi.org/10.1007/s00216-020-03095-5DOI Listing
February 2021

BTEX compounds leachates from cigarette butts into water environment: A primary study.

Environ Pollut 2021 Jan 30;269:116185. Epub 2020 Nov 30.

Instrumental Analytical Chemistry and Centre for Water and Environmental Research (ZWU), Faculty of Chemistry, University of Duisburg-Essen, Universitätsstr. 5, Essen, Germany.

Cigarette butts (CBs) are the most abundant types of litter in the environment and may contain toxic chemicals such as BTEX that pose serious risks to the water bodies and health of aquatic organisms. So far there is no systematic study on BTEX compounds (benzene, toluene, ethylbenzene, o-xylene, and p-xylene) leaching from CBs into water environments. In this work, the leaching concentrations of BTEX compounds in deionized water (DW) and river water (RW) samples were studied for the first time. The mean concentrations of benzene, toluene, ethylbenzene, p-xylene, and o-xylene at contact times of 15 min to 1 day in water samples ranged from 0.13 to 0.18, 0.39-0.9, 0.11-0.25, 0.12-0.38, and 0.09-0.19 μgL respectively. Benzene, toluene, ethylbenzene, o-xylene and p-xylene were detected at all contact times in both DW and RW samples. There were no significant differences of the leachate levels of BTEX compounds between DW and RW samples. The highest and lowest mean concentration levels in both DW and RW samples were determined for toluene and o-xylene respectively. The time after smoking had a significant effect on BTEX levels in leachates. The concentration levels of benzene, toluene, ethylbenzene, o-xylene and p-xylene leachates in water samples, after only 15 min, were reduced by 100, 93, 70, 68, and 59 percent respectively. Our data revealed that leached concentrations of benzene did not exceed the Water Framework Directive (WFD) guidelines, but with regard to the amount of CBs littered each year and other toxic chemicals contents of CBs this can still be a threat for aquatic creatures and possibly humans as well. Further studies are needed to cover the knowledge gap on the toxic leachates from CBs into water systems.
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http://dx.doi.org/10.1016/j.envpol.2020.116185DOI Listing
January 2021

Matrix composition during ozonation of N-containing substances may influence the acute toxicity towards Daphnia magna.

Sci Total Environ 2021 Apr 6;765:142727. Epub 2020 Oct 6.

Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstr. 5, 45141 Essen, Germany; Centre for Water and Environmental Research (ZWU), University of Duisburg-Essen, Universitätsstr. 2, 45141 Essen, Germany; IWW Water Centre, Moritzstraße 26, 45476, Mülheim an der Ruhr, Germany. Electronic address:

Micropollutants reach the aquatic environment through wastewater treatment plant effluents. Ozonation, applied in wastewater treatment for micropollutants abatement, can yield transformation products (TP), which might be of ecotoxicological concern. Previous studies on TP formation were mostly performed in ultrapure water. However, the water matrix can have a substantial influence and lead to unpredictable yields of TPs with toxicological potential. In this study the acute toxicity (immobilization) of the parent substances (isoproturon and metoprolol) and also of available TPs of isoproturon, metoprolol and diclofenac towards Daphnia magna (D. magna) were investigated. Further, the acute toxicity of TP mixtures, formed during ozonation of isoproturon, metoprolol and diclofenac was evaluated in the following systems: in the presence of radical scavengers (tert-butanol and dimethyl sulfoxide) and in the presence of hypobromous acid (HOBr), a secondary oxidant in ozonation. For all tested substances and TP standards, except 2,6-dichloroaniline (EC 1.02 mg/L (48 h)), no immobilization of D. magna was detected. Ozonated pure water and wastewater did not show an immobilization effect either. After ozonation of diclofenac in the presence of dimethyl sulfoxide 95% (48 h) of the daphnids were immobile. Ozonation of parent substances, after the reaction with HOBr, showed no effect for isoproturon but a high effect on D. magna for diclofenac (95% immobilization (48 h)) and an even higher effect for metoprolol (100% immobilization (48 h)). These results emphasize that complex water matrices can influence the toxicity of TPs as shown in this study for D. magna.
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http://dx.doi.org/10.1016/j.scitotenv.2020.142727DOI Listing
April 2021

Determination of free chlorine based on ion chromatography-application of glycine as a selective scavenger.

Anal Bioanal Chem 2020 Nov 18;412(28):7713-7722. Epub 2020 Sep 18.

Faculty of Chemistry, Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstraße 5, 45141, Essen, Germany.

Free available chlorine (FAC) is the most widely used chemical for disinfection and in secondary disinfection; a minimum chlorine residual must be present in the distribution system. FAC can also be formed as an impurity in ClO production as well as a secondary oxidant in the ClO application, which has to be monitored. In this study, a new method is developed based on the reaction of FAC with glycine in which the amine group selectively scavenges FAC and the N-chloroglycine formed can be measured by ion chromatography with conductivity detector (IC-CD). Utilizing IC for N-chloroglycine measurement allows this method to be incorporated into routine monitoring of drinking water anions. For improving the sensitivity, IC was coupled with post-column reaction and UV detection (IC-PCR-UV), which was based on iodide oxidation by N-chloroglycine resulting in triiodide. The method performance was quantified by comparison of the results with the N,N-diethyl-p-phenylenediamine (DPD) method due to the unavailability of an N-chloroglycine standard. The N-chloroglycine method showed limits of quantification (LOQ) of 24 μg L Cl and 13 μg L Cl for IC-CD and IC-PCR-UV, respectively. These values were lower than those of DPD achieved in this research and in ultrapure water. Measurement of FAC in the drinking water matrix showed comparable robustness and sensitivity with statistically equivalent concentration that translated to recoveries of 102% for IC-CD and 105% for IC-PCR-UV. Repeatability and reproducibility performance were enhanced in the order of DPD, IC-CD, and IC-PCR-UV. Measurement of intrinsic FAC in the ClO application revealed that the N-chloroglycine method performed considerably better in such a system where different oxidant species (ClO, FAC, chlorite, etc.) were present.
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http://dx.doi.org/10.1007/s00216-020-02885-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7550385PMC
November 2020

Evaluation of Nontarget Long-Term LC-HRMS Time Series Data Using Multivariate Statistical Approaches.

Anal Chem 2020 09 2;92(18):12273-12281. Epub 2020 Sep 2.

Instrumental Analytical Chemistry (IAC) and Centre for Water and Environmental Research (ZWU), University of Duisburg-Essen, UnivFersitaetsstrasse 5, D-45141 Essen, Germany.

The use of liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS) has steadily increased in many application fields ranging from metabolomics to environmental science. HRMS data are frequently used for nontarget screening (NTS), i.e., the search for compounds that are not previously known and where no reference substances are available. However, the large quantity of data produced by NTS analytical workflows makes data interpretation and time-dependent monitoring of samples very sophisticated and necessitates exploiting chemometric data processing techniques. Consequently, in this study, a prioritization method to handle time series in nontarget data was established. As proof of concept, industrial wastewater was investigated. As routine industrial wastewater analyses monitor the occurrence of a limited number of targeted water contaminants, NTS provides the opportunity to detect also unknown trace organic compounds (TrOCs) that are not in the focus of routine target analysis. The developed prioritization method enables reducing raw data and including identification of prioritized unknown contaminants. To that end, a five-month time series for industrial wastewaters was utilized, analyzed by liquid chromatography-time-of-flight mass spectrometry (LC-qTOF-MS), and evaluated by NTS. Following peak detection, alignment, grouping, and blank subtraction, 3303 features were obtained of wastewater treatment plant (WWTP) influent samples. Subsequently, two complementary ways for exploratory time trend detection and feature prioritization are proposed. Therefore, following a prefiltering step, featurewise principal component analysis (PCA) and groupwise PCA (GPCA) of the matrix (temporal wise) were used to annotate trends of relevant wastewater contaminants. With sparse factorization of data matrices using GPCA, groups of correlated features/mass fragments or adducts were detected, recovered, and prioritized. Similarities and differences in the chemical composition of wastewater samples were observed over time to reveal hidden factors accounting for the structure of the data. The detected features were reduced to 130 relevant time trends related to TrOCs for identification. Exemplarily, as proof of concept, one nontarget pollutant was identified as -methylpyrrolidone. The developed chemometric strategies of this study are not only suitable for industrial wastewater but also could be efficiently employed for time trend exploration in other scientific fields.
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http://dx.doi.org/10.1021/acs.analchem.0c01897DOI Listing
September 2020

Optimization and validation of automated solid-phase microextraction arrow technique for determination of phosphorus flame retardants in water.

J Chromatogr A 2020 Aug 17;1626:461349. Epub 2020 Jun 17.

Instrumental Analytical Chemistry and Centre for Water and Environmental Research, University of Duisburg-Essen, Universitätsstraße 5, 45141 Essen, Germany.

In the present work, a very sensitive and fully automated direct immersion PAL SPME Arrow procedure, coupled with GC-MS, has been developed and validated for determination of nine phosphorus flame retardants in different types of water samples (river, drinking and rainwater). PDMS/DVB was selected among three commercially available SPME Arrows (PDMS/DVB, DVB/PDMS/CWR and PDMS/CWR), since it resulted in the best sensitivity. The important experimental parameters were optimized via a central composite design response surface methodology and as result, extraction time of 65 min, extraction temperature of 80 °C and added salt concentration of 19% (w/v), were selected as the optimum values. The optimized method showed linear response over the calibration range (2 - 500 ng L), with R-values higher than 0.9937. The precision (RSD%) measured by replicate analyses (n = 7) was estimated at 2 and 100 ng L and was less than 29% and 21%, respectively. The LOQ of PAL SPME Arrow, calculated as S/N = 10, was between 0.2 and 1.2 ng L (for triphenyl phosphate and tris-(1‑chloro‑2-propyl) phosphate, respectively) with extraction efficiencies between 5.9 and 31% (for tris-(1,3-dichloro-2-propyl) phosphate and tri-n‑butyl phosphate, respectively). To assess the performance of the developed technique for real samples, two river water samples, tap water from two regions and a rainwater sample were analyzed. Most of the target analytes were observed in the river samples with concentrations of 1.0 - 250 ng L and the obtained recoveries at 50 ng L ranged between 60 and 107%. Considering the figures of merit of the optimized method, PAL SPME Arrow-GC-MS showed to be the most sensitive analytical approach for determination of phosphorus flame retardants in water, with satisfying precision and accuracy, compared with conventional SPME-NPD, LLE-GC-MS and SPE-LC-MS/MS.
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http://dx.doi.org/10.1016/j.chroma.2020.461349DOI Listing
August 2020

Effect of ozone stress on the intracellular metabolites from Cobetia marina.

Anal Bioanal Chem 2020 Sep 16;412(23):5853-5861. Epub 2020 Jul 16.

Applied Analytical Chemistry & Teaching and Research Center for Separation, University of Duisburg-Essen, Universitaetsstr. 5, 45141, Essen, Germany.

A GCxGC-MS system was employed with a non-polar × mid-polar column set for the metabolic non-target analysis of Cobetia marina, the model bacteria for marine biofouling. C. marina was treated with ozone to investigate the intracellular metabolic state change under oxidative stress. A minimal inhibitory concentration test was involved to guarantee that the applied ozone dosages were not lethal for the cells. In this study, non-target analyses were performed to identify the metabolites according to the NIST database. As a result, over 170 signals were detected under normal living conditions including 35 potential metabolites. By the comparison of ozone-treated and non-treated samples, five compounds were selected to describe observed trends of signals in the contour plots. Oleic acid exhibited a slight growth by increasing ozone dosage. In contrast, other metabolites such as the amino acid L-proline showed less abundance after ozone treatment, which was more evident once ozone dosage was raised. Thus, this work could provide a hint for searching for up/downregulating factors in such environmental stress conditions for C. marina. Graphical abstract.
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http://dx.doi.org/10.1007/s00216-020-02810-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7413921PMC
September 2020

Stable isotope analysis spills the beans about spatial variance in trophic structure in a fish host - parasite system from the Vaal River System, South Africa.

Int J Parasitol Parasites Wildl 2020 Aug 28;12:134-141. Epub 2020 May 28.

Department of Zoology, University of Johannesburg, 524 Auckland Park, Johannesburg, 2006, South Africa.

Stable isotope analysis offers a unique tool for comparing trophic interactions and food web architecture in ecosystems based on analysis of stable isotope ratios of carbon (C/C) and nitrogen (N/N) in organisms. were collected from six sites along the Vaal River, South Africa and were assessed for ectoparasites and endoparasites. (Copepoda), and (Cestoda), and larval sp. (Nematoda) were collected from the gills, intestine and mesenteries, respectively. Signatures of δC and δN were analysed in host muscle tissue and parasites using bulk stable isotope analysis. Variable stable isotope enrichment between parasites and host were observed; and the host shared similar δN signatures and endoparasites being depleted in δC and δN relative to the host. Differences in stable isotope enrichment between parasites could be related to the feeding strategy of each parasite species collected. Geographic and spatial differences in enrichment of stable isotopes observed in hosts were mirrored by parasites. As parasites rely on a single host for meeting their nutritional demands, stable isotope variability in parasites relates to the dietary differences of host organisms and therefore variations in baseline stable isotope signatures of food items consumed by hosts.
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http://dx.doi.org/10.1016/j.ijppaw.2020.05.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7286960PMC
August 2020

Development of an LC-MS method for determination of nitrogen-containing heterocycles using mixed-mode liquid chromatography.

Anal Bioanal Chem 2020 Aug 26;412(20):4921-4930. Epub 2020 May 26.

Faculty of Chemistry, Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstraße 5, 45141, Essen, Germany.

N-containing heterocycles (NCHs) are largely used as precursors for pharmaceuticals and can enter the environment. Some NCHs have been shown to be toxic, persistent, and very mobile in the environment. Thus, they have received increasing attention in the past years. However, the analysis of these polar compounds in environmental samples is still a challenge for liquid chromatography. This paper investigates the use of mixed-mode liquid chromatography (MMLC), which has reversed-phase and ion exchange characteristics for measurements of NCHs in water. NCHs with low pK (i.e., < 2.5) display mainly reversed-phase interactions (neutral species) with the stationary phase and those with higher pK (i.e., > 5) interact by a mixture of reversed-phase/ion exchange/HILIC mechanism. It was also shown that the presented method performs well in the quantification of the majority of the selected NCHs in surface water with MDLs between 3 and 6 μg/L, a low matrix effect and recoveries in the range of 77-96% except for pyridazine exhibiting 32% were achieved. The method was successfully employed to follow the degradation of NCHs in ozonation.
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http://dx.doi.org/10.1007/s00216-020-02665-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7334287PMC
August 2020

Carbon Isotope Fractionation of Substituted Benzene Analogs during Oxidation with Ozone and Hydroxyl Radicals: How Should Experimental Data Be Interpreted?

Environ Sci Technol 2020 06 20;54(11):6713-6722. Epub 2020 May 20.

Faculty of Chemistry, Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstrasse 5, D-45141 Essen, Germany.

Oxidative processes frequently contribute to organic pollutant degradation in natural and engineered systems, such as during the remediation of contaminated sites and in water treatment processes. Because a systematic characterization of abiotic reactions of organic pollutants with oxidants such as ozone or hydroxyl radicals by compound-specific stable isotope analysis (CSIA) is lacking, stable isotope-based approaches have rarely been applied for the elucidation of mechanisms of such transformations. Here, we investigated the carbon isotope fractionation associated with the oxidation of benzene and several methylated and methoxylated analogs, namely, toluene, three xylene isomers, mesitylene, and anisole, and determined their carbon isotope enrichments factors () for reactions with ozone ( = -3.6 to -4.6 ‰) and hydroxyl radicals ( = 0.0 to -1.2‰). The differences in isotope fractionation can be used to elucidate the contribution of the reactions with ozone or hydroxyl radicals to overall transformation. Derivation of apparent kinetic isotope effects (AKIEs) for the reaction with ozone, however, was nontrivial due to challenges in assigning reactive positions in the probe compounds for the monodentate attack leading to an ozone adduct. We present several options for this step and compare the outcome to quantum chemical characterizations of ozone adducts. Our data show that a general assignment of reactive positions for reactions of ozone with aromatic carbons in , , or positions is not feasible and that AKIEs of this reaction should be derived on a compound-by-compound basis.
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http://dx.doi.org/10.1021/acs.est.0c00620DOI Listing
June 2020

Hydrophobicity-water/air-based enrichment cell for microplastics analysis within environmental samples: A proof of concept.

MethodsX 2020 5;7:100732. Epub 2019 Dec 5.

Instrumental Analytical and Environmental Chemistry, Faculty of Chemistry, Niederrhein University of Applied Sciences, Frankenring 20, D-47798 Krefeld, Germany.

The analysis of microplastics in sediments, soils or beach samples is commonly paired with a separation step to enrich microplastics or to remove non-plastics, respectively. Those steps are often very time consuming and are performed in presence of high concentrated solvents. The latter are also suspected to corrode or decompose the analyte particles, which hamper further identification processes. This paper describes a new fast and effective microplastics separation apparatus for analytical issues that was based on hydrophobic adhesion of microplastics and fine air bubbles. The presented prototype could successfully enrich over 90 % of 30ppm microplastics in 200 g sand in 20 min. Additionally, it could be demonstrated that the new separation technique was very suitable for further microplastics identification by FTIR microscopy. In this context, a sample with different polymers and matrix components was analyzed and the results were presented within this article. •.•.• 20 min .
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http://dx.doi.org/10.1016/j.mex.2019.11.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7182761PMC
December 2019

Worldwide bottled water occurrence of emerging contaminants: A review of the recent scientific literature.

J Hazard Mater 2020 06 14;392:122271. Epub 2020 Feb 14.

Akademie für Menschliche Medizin GmbH, Krauskopfallee 27, 65388, Schlangenbad, Germany.

Contaminants of emerging concern (CECs) have recently been detected in bottled water and have brought about discussions on possible risks for human health. However, a systematic review of CECs in bottled water is currently lacking due to the relatively new introduction and/or detection of these pollutants. Hence, this paper reviews the existing studies on the presence of six major groups of emerging contaminants including microplastics (MPs), pharmaceuticals and personal care products (PPCPs), bisphenol A (BPA), phthalates, alkylphenols (APs), and perfluoroalkyl and polyfluoroalkyl substances (PFASs) in bottled water from different countries. Also, the findings related to CECs' levels, their possible sources, and their risks are summarized. The gathered data indicate that MPs within the size range of 1-5 μm are the most predominant and potentially toxic classes of MPs in bottled water. In addition, PPCPs, PFASs, APs, and BPA occur in concentration levels of ng/L, while phthalates occur in the μg/L level in bottled water. The bottle type plays an important role in the contamination level. As expected, water in plastic bottles with plastic caps is more polluted than in glass bottles. However, other sources of contamination such as contact materials during cleaning, bottling, and storage are not negligible. Based on the gathered data in this review, the CEC levels except for MPs (no threshold values) in bottled water of most countries do not raise a safety concern for the human. However, the occurrence of individual CECs and their association in bottled water need more accurate data to understand their own/synergistic effects on human health.
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http://dx.doi.org/10.1016/j.jhazmat.2020.122271DOI Listing
June 2020

Identification of microplastics in wastewater after cascade filtration using Pyrolysis-GC-MS.

MethodsX 2020 19;7:100778. Epub 2019 Dec 19.

Institut für Energie - und Umwelttechnik e.V. (IUTA, Institute of Energy and Environmental Technology), Bliersheimer Str. 58-60, 47229 Duisburg, Germany.

The combination of a representative microplastic sampling method and a fast-quantitative analysis using Pyrolysis-GC-MS (Py-GC-MS) for investigation of the microplastic load and mass balances is presented in this work. A representative microplastic filtration requires a method allowing quick extraction of the sample. The developed steel based cascadic microplastic filtration uses steel basket filters with mesh sizes of 100 μm, 50 μm and 10 μm and a mean recovery of 86 % without cross contamination was achieved. Thermoanalytical methods have the advantage of minimal sample preparation with short analysis times. The presented platinum filament-based Py-GC-MS method requires little sample preparation and quantification limits for polystyrene (PS) and polyethylene (PE) were 0.03 μg and 1 μg absolute, respectively. The relative standard deviation of the analytical method is 11 %. The combined method allows representative sampling and analysis of MP from water bodies and waste water treatment plants within 48 h. •Presentation of a validated steel based cascadic microplastic filtration plant.•Fast and reproduceable Py-GC-MS analysis method for microplastic.•Py-GC-MS allows microplastic analysis with little sample preparation.
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http://dx.doi.org/10.1016/j.mex.2019.100778DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7152672PMC
December 2019

Automated rapid & intelligent microplastics mapping by FTIR microscopy: A Python-based workflow.

MethodsX 2020 13;7:100742. Epub 2019 Dec 13.

Instrumental Analytical and EnvironmentalChemistry, Faculty of Chemistry, Niederrhein University of Applied Sciences, Frankenring 20, D-47798, Krefeld, Germany.

The analysis of environmental microplastic particles using FTIR microscopy is a challenging task, due to the very high number of individual particles within a single sample. Therefore, automatable, fast and robust approaches are highly requested. Micro particles were commonly enriched on filters, and sub- or the whole filter area was investigated, which took more than 20h and produced millions of data, which had to be evaluated. This paper presents a new approach of such filter area analysis using an intelligent algorithm to measure only those spots on a filter that would produce evaluable FTIR data. Empty spaces or IR absorbers like carbon black particles were not measured which successfully reduced the total analysis time from 50h to 7h. The presented method is based on system independent Python workflow and can easily be implemented on other FTIR systems. •••.
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http://dx.doi.org/10.1016/j.mex.2019.11.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7063176PMC
December 2019

Enrichment-free analysis of anionic micropollutants in the sub-ppb range in drinking water by capillary electrophoresis-high resolution mass spectrometry.

Anal Bioanal Chem 2020 Aug 9;412(20):4857-4865. Epub 2020 Mar 9.

Department of Chemistry, Aalen University, Beethovenstraße 1, 73430, Aalen, Germany.

Reversed-phase liquid chromatography (RPLC) used for water analysis is not ideal for the analysis of highly polar and ionic contaminants because of low retention. Capillary electrophoresis (CE), on the other hand, is perfectly suited for the separation of ionic compounds but rarely applied in environmental analysis due to the weak concentration sensitivity when coupled to mass spectrometry (MS). However, novel interface designs and MS technology strongly improve the sensitivity. Here, a method is presented enabling the screening of anionic micropollutants in drinking water without sample pretreatment by coupling of CE to an Orbitrap mass spectrometer by a nanoflow sheath liquid interface. Targeted analysis of halogenated acetic acids, trifluoromethanesulfonic acid, and perfluorooctanoic and perfluorooctanesulfonic acid was conducted in drinking water samples which were chlorinated for disinfection. A bare fused silica capillary with an optimized background electrolyte (BGE) for separation consisting of 10% acetic acid with 10% isopropanol with large volume sample injection and optimized interface parameters offer limits of quantification in the range of < 0.1 to 0.5 μg/L with good linearity (R > 0.993) and repeatability (14% standard deviation in area). Concentrations of the target analytes ranged from 0.1 to 6.2 μg/L in the water samples. Masses corresponding to halogenated methanesulfonic acids have been found as suspects and were subsequently verified by standards. Mono-, dichloro-, and bromochloro methanesulfonic acid were quantified in a range of 0.2 to 3.6 μg/L. Furthermore, five sulfonic acids, four organosulfates, and the artificial sweeteners acesulfame and cyclamate as well as inorganics such as halides, halogenates, phosphate, and sulfate could be determined as suspects among more than 300 features in a non-targeted screening. Overall, this approach demonstrates the great potential of CE-nanoESI-MS for the screening of ionic contaminants in environmental samples, complementary to chromatographic approaches.
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http://dx.doi.org/10.1007/s00216-020-02525-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7334245PMC
August 2020

Persistent and mobile organic compounds-an environmental challenge.

Anal Bioanal Chem 2020 08;412(20):4761-4762

Instrumental Analytical Chemistry and Centre for Water and Environmental Research, Universitätsstr. 5, 45141, Essen, Germany.

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http://dx.doi.org/10.1007/s00216-020-02542-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7334256PMC
August 2020

You are how you eat: differences in trophic position of two parasite species infecting a single host according to stable isotopes.

Parasitol Res 2020 Apr 6;119(4):1393-1400. Epub 2020 Feb 6.

Department of Zoology, University of Johannesburg, 524 Auckland Park, Johannesburg, 2006, South Africa.

Parasitism is commonly recognised as a consumer strategy, although, the interaction of parasites in communities and ecosystems are generally poorly understood. As parasites are integral parts of food webs, analysis of the trophic interactions between parasites and hosts was assessed through comparison of stable isotope ratios of carbon (C/C) and nitrogen (N/N). Largemouth yellowfish (Labeobarbus kimberleyensis) infected with the Asian tapeworm (Schyzocotyle acheilognathi) were collected from the Vaal Dam. Signatures of δC and δN were assessed in host muscle and liver tissue, and cestodes using an elemental analyser coupled with an isotope ratio-mass spectrometer (EA-IRMS). Hosts were enriched by 4.1‰ in the heavy nitrogen isotope with respect to the S. acheilognathi and therefore occupy a higher trophic position than the parasite. Comparison of δC indicates that dietary sources of carbon in cestodes are derived from the host liver. Comparison of stable isotope signatures between Paradiplozoon ichthyoxanthon (another common parasite of the Largemouth yellowfish in the Vaal River) and S. acheilognathi showed that the monogenean was enriched by 5.3‰ in N which accounts for a difference of almost two trophic positions. Isotope differences in the host-parasite system considered indicate that differences can be related to the mode of nutrient acquisition employed by host and parasites. Cestodes, being depleted in both C and N relative to the host and monogenean (P. ichthyoxanthon), indicate that S. acheilognathi assimilates nutrients derived from the host metabolism which are released from the liver.
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http://dx.doi.org/10.1007/s00436-020-06619-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7176597PMC
April 2020

Polycyclic aromatic hydrocarbons (PAHs) leachates from cigarette butts into water.

Environ Pollut 2020 Apr 7;259:113916. Epub 2020 Jan 7.

Instrumental Analytical Chemistry and Centre for Water and Environmental Research (ZWU), Faculty of Chemistry, University of Duisburg-Essen, Universitätsstr. 5, Essen, Germany; IWW Water Centre, Moritzstraße 26, 45476, Mülheim an der Ruhr, Germany; Centre for Water and Environmental Research (ZWU), Universitätsstraße 5, 45141, Essen, Germany.

Cigarette butts (CBs) are the most common littered items in the environment and may contain high amounts of polycyclic aromatic hydrocarbons (PAHs) from incomplete tobacco leave burning. The potential relevance of PAHs stemming from CBs for aquatic systems remain unclear since to date there is no systematic study on PAHs leaching from CBs. Therefore, in this study the leaching concentrations of 16 EPA-PAHs (except benzo(ghi)perylene) in 3 different types of water were measured. The concentrations of ΣPAHs leachates from 4 h to 21 days ranged from 3.9 to 5.7, 3.3-5.5, and 3.0-5.0 μg L for deionized, tap, and river waters, respectively. For all contact times, there were no substantial differences of the leachate concentrations of PAHs among different water types. Lighter PAHs had the highest concentrations among the detected PAHs and they were detected in the leachates already after 4 h. Concentrations of indeno(1,2,3-cd)pyrene, and dibenz(a,h)anthracene were below the limit of detection in all water samples at different contact times. At all contact times naphthalene and fluorene had the highest concentrations among the studied PAHs. Tap and river water samples with addition of sodium azide as chemical preservative contained significantly higher concentration of ΣPAHs. Our leaching data showed that leached concentrations of PAHs exceeded the Water Framework Directive (WFD) standards and considering the number of CBs annually littered this may pose a risk to aquatic organisms and potentially also humans.
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http://dx.doi.org/10.1016/j.envpol.2020.113916DOI Listing
April 2020

Identification of unknowns in industrial wastewater using offline 2D chromatography and non-target screening.

Sci Total Environ 2020 Mar 30;706:135835. Epub 2019 Nov 30.

Instrumental Analytical Chemistry (IAC) and Centre for Water and Environmental Research (ZWU), University of Duisburg-Essen, Universitaetsstrasse 5, D-45141 Essen, Germany; IWW Zentrum Wasser, Moritzstrasse 26, 45476 Mülheim an der Ruhr, Germany. Electronic address:

Industrial wastewater is characterised by a complex composition of trace organic compounds (TrOC) in a difficult matrix. The identification of unknown pollutants is of high interest. On the one hand to ensure protection of the environment by elucidating contaminations and on the other hand to protect the biological treatment step in the wastewater treatment plant (WWTP). Due to the high variability of the matrix, the identification of compounds of interest is very time consuming and often unsuccessful. To overcome this limitation, a prioritisation method was developed to identify so called 'known unknowns', i.e. compounds frequently detected but not identified, as prioritised compounds in industrial wastewater. The method based on an offline two-dimensional (offline 2D) liquid chromatography (LC) approach with ultra violet (UV) detection in the first and high-resolution mass spectrometry (HRMS) in the second dimension. As a proof of concept, an identification process of one 'known unknown' is described. The compound was identified as a dichlorodinitrophenol isomer by retention time in two dimensions, UV spectrum, exact mass, mass fragmentation and H- NMR. As prioritisation method, the offline 2D LC in combination with non-target analysis provides a powerful workflow to determine tentative structures of unknown organic compounds in industrial wastewater.
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http://dx.doi.org/10.1016/j.scitotenv.2019.135835DOI Listing
March 2020

Comparison of Software Tools for Liquid Chromatography-High-Resolution Mass Spectrometry Data Processing in Nontarget Screening of Environmental Samples.

Anal Chem 2020 01 27;92(2):1898-1907. Epub 2019 Dec 27.

Instrumental Analytical Chemistry , University of Duisburg-Essen , Universitätsstrasse 5 , D-45141 Essen , Germany.

The field of high-resolution mass spectrometry has undergone a rapid progress in the last years due to instrumental improvements leading to a higher sensitivity and selectivity of instruments. A variety of qualitative screening approaches, summarized as nontarget screening, have been introduced and have successfully extended the environmental monitoring of organic micropollutants. Several automated data processing workflows have been developed to handle the immense amount of data that are recorded in short time frames by these methods. Most data processing workflows include similar steps, but underlying algorithms and implementation of different processing steps vary. In this study the consistency of data processing with different software tools was investigated. For this purpose, the same raw data files were processed with the software packages MZmine2, enviMass, Compound Discoverer, and XCMS online and resulting feature lists were compared. Results show a low coherence between different processing tools, as overlap of features between all four programs was around 10%, and for each software between 40% and 55% of features did not match with any other program. The implementation of replicate and blank filter was identified as one of the sources of observed divergences. However, there is a need for a better understanding and user instructions on the influence of different algorithms and settings on feature extraction and following filtering steps. In future studies it would be of interest to investigate how final data interpretation is influenced by different processing software. With this work we want to encourage more awareness on data processing as a crucial step in the workflow of nontarget screening.
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http://dx.doi.org/10.1021/acs.analchem.9b04095DOI Listing
January 2020
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