Research in the group of environmental analytical chemistry focuses on development of novel methods for the analysis of organic contaminants in the aquatic environment. For the sensitive and reliable quantification of targeted contaminants such as pesticides, pharmaceuticals, industrial chemicals and their transformation products, we use mass spectrometry (Oribtrap and Triplequad technology) coupled to liquid chromatography or gas chromatography. For the multi-compound screening (currently more than 500 target compounds) in ground water, surface water and waste water we apply LC-ESI-Orbitrap methods after solid phase enrichment of the samples (offline or online coupled to multi-layer cartridges). For the ultra-sensitive detection of single compounds or compound classes, such as glyphosate, pyrethroid insecticides, or perfluorinated compounds, LC-ESI-Triplequad or GC-APCI-Triplequad methods has been developed. Comprehensive suspect and non-target (general unknown) screening approaches analysis has been established using LC-Orbitrap methods. Our objective is to address blind spots within the current environmental analysis. For this the development of innovative and comprehensive analytical methods is needed as well as new algorithms and workflows for the mining of high resolution mass spectrometry data have to be established. Several open-access software tools resulted so far from our research efforts (e. g. http://www.envipat.eawag.ch/) and more free-to-use software is underway. To adequately determine the spatial and time-resolved exposure of water bodies in field studies we currently expedited the improvement of existing active and passive water sampling techniques and explore the capabilities of transportable mass spectrometers for on-site measurements.
For our research we are running the following major instruments:
High resolution mass spectrometers: Orbitrap XL, QExactive, QExactive Plus (all Thermo Scientific); all Orbitraps are equipped with online-SPE-HPLC (CTC, Flux) and nano-UHPLC (Dionex) as well as with ESI, APCI, APPI sources (Thermo Scientific)
Triplequad mass spectrometers: Thermo Scientific Vantage and Agilent 6495 all Triplequads are equipped with online-SPE-HPLC; Vantage is also coupled to a Dionex Cap-IC; the Agilent 6495 is also coupled to a GC over an APCI interface
Singlequad mass spectrometers: Thermo Scientific DSQ and Trace DSQ (maintained by the stable isotope lab of Thomas Hofstetter) all MS are equipped with a gas chromatograph (EI source), split/splitless and on-column injector, PTV, purge and trap
Quantitative target and systematic non-target analysis of polar organic micro-pollutants along the river Rhine using high-resolution mass-spectrometry – identification of unknown sources and compounds
In this study, the contamination by polar organic pollutants was investigated along the Rhine River, an important source of drinking water for 22 million people in central Europe. Following the flow of the river, a traveling water mass was sampled using weekly flow-proportional composite samples at ten different downstream sites, including main tributaries. Using a broad analytical method based on solid phase extraction and high-resolution mass spectrometry, the water was analyzed for more than 300 target substances. While the water in Lake Constance contained only 83 substances in often low concentrations, the number of detects found in the water phase increased to 143 substances and a weekly load of more than 7 tons at the last sampling site, the Dutch-German border. Mostly present were chemicals originating from wastewater treatment plants, especially the artificial sweetener Acesulfam and two pharmaceuticals, Metformin and Gabapentin, which dominate the weekly load up to 58%. Although the sample campaign was performed in a dry period in early spring, a large variety of pesticides and biocides were detected. Several industrial point sources were identified along the waterway's 900 km journey, resulting in high concentrations in the tributaries and loads of up to 160 kg. Additionally, an unbiased non-target analysis was performed following two different strategies for the prioritization of hundreds of potentially relevant unknown masses. While for the first prioritization strategy, only chlorinated compounds were extracted from the mass spectrometer datasets, the second prioritization strategy was performed using a systematic reduction approach between the different sampling sites. Among others, two substances that never had been detected before in this river, namely, the muscle relaxant Tizanidine and the solvent 1,3-Dimethyl-2-imidazolidinone (DMI), were identified and confirmed, and their loads were roughly estimated along the river.
Ruff, M.; Mueller, M. S.; Loos, M.; Singer, H. P. (2015) Quantitative target and systematic non-target analysis of polar organic micro-pollutants along the river Rhine using high-resolution mass-spectrometry – identification of unknown sources and compounds, Water Research, 87, 145-154, doi:10.1016/j.watres.2015.09.017, Institutional Repository
Elimination of polar micropollutants and anthropogenic markers by wastewater treatment in Beijing, China
Anthropogenic contamination of surface waters in Asia is on the increase. While polar organic contaminants are gradually recognized for their impacts on aquatic ecosystems in the Western World, less is known about the situation in Asia. In developing countries like China, water resources are particularly vulnerable. We investigated the occurrence, elimination, and per capita loads of a wide range of pharmaceuticals, household chemicals and pesticides in five Beijing WWTPs representative for megacities in China, and compare the efficiency of different treatment processes. Based on initial screening for 268 micropollutants using high-resolution mass spectrometry, 33 compounds were examined in detail. Pollutant concentrations in raw wastewater ranged from <0.02 μg L−1 for pesticides to >20 μg L−1 for caffeine and the contrast agent iopromide. Concentrations in the WWTP effluents were generally <1 μg L−1, except for some pharmaceuticals, iopromide (1.2–18 μg L−1), caffeine (0.025–2.3 μg L−1), and the artificial sweetener sucralose (2.7–3.5 μg L−1). Elimination efficiencies varied greatly from <1% to close to 100%, with macrolides, some sulfonamides, metronidazole, iopromide, and 4-acetamidoantipyrine being the most persistent compounds. Total per capita loads of the investigated micropollutants were lower than in communal wastewater of Europe, amounting to 7.9–12.2 and 2.0–6.5 g d−1 1000 inhabitants−1 in the influents and effluents, respectively, with an average release of ∼100 kg d−1 by the 11.4 million people and 2.3 million m3 of wastewater treated per day. Since the wastewater effluents are often used for agricultural irrigation, residual organic pollutants pose a threat to food safety, the development of antibacterial resistance, and combined effects of micropollutants in the aquatic environment.
Evaluation of in-situ calibration of Chemcatcher passive samplers for 322 micropollutants in agricultural and urban affected rivers
In a large field study, the in-situ calibration of the Chemcatcher® passive sampler – styrenedivinylbenzene (SDB) covered by a polyether sulfone (PES) membrane – was evaluated for 322 polar organic micropollutants. Five rivers with different agricultural and urban influences were monitored from March to July 2012 with two methods i) two-week time-proportional composite water samples and ii) two-week passive sampler deployment. All substances – from different substance classes with logKow −3 to 5, and neutral, anionic, cationic, and zwitterionic species – were analyzed by liquid-chromatography high-resolution tandem mass spectrometry. This study showed that SDB passive samplers are well-suited for the qualitative screening of polar micropollutants because the number of detected substances was similar (204 for SDB samples vs. 207 for composite water samples), limits of quantification were comparable (median: 1.3 ng/L vs. 1.6 ng/L), and the handling in the field and laboratory is fast and easy. The determination of in-situ calibrated sampling rates (field Rs) was possible for 88 compounds where the R2 from the regression (water concentration vs. sampled mass on SDB disk) was >0.75. Substances with moderately fluctuating river concentrations such as pharmaceuticals showed much better correlations than substances with highly fluctuating concentrations such as pesticides (R2 > 0.75 for 93% and 60% of the investigated substances, respectively). Flow velocity (0.05–0.8 m/s) and temperature (5–20 °C) did not have an evident effect on the field Rs. It was observed that ionic species had significantly lower field Rs than neutral species. Due to the complexity of the different transport processes, a correlation between determined field Rs and logDow could only predict Rs with large uncertainties. We conclude that only substances with relatively constant river concentrations can be quantified accurately in the field by passive sampling if substance-specific Rs are determined. For that purpose, the proposed in-situ calibration is a very robust method and the substance specific Rs can be used in future monitoring studies in rivers with similar environmental conditions (i.e., flow velocity, temperature, pH).
Moschet, C.; Vermeirssen, E. L. M.; Singer, H.; Stamm, C.; Hollender, J. (2015) Evaluation of in-situ calibration of Chemcatcher passive samplers for 322 micropollutants in agricultural and urban affected rivers, Water Research, 71, 306-317, doi:10.1016/j.watres.2014.12.043, Institutional Repository
Accelerated isotope fine structure calculation using pruned transition trees
A fast and memory-efficient calculation of theoretical isotope patterns is crucial for the routine interpretation of mass spectrometric data. For high-resolution experiments, calculations must procure the exact masses and probabilities of relevant isotopologues over a wide range of polyisotopic compounds, while pruning low-probable ones. Here, a novel albeit simple treelike structure is introduced to swiftly derive sets of relevant subisotopologues for each element in a molecule, which are then combined to the isotopologues of the full molecule. In contrast to existing approaches, transitions via single replacements of the most abundant isotope per element are used in separable tree branches to derive subisotopologues from each other. Moreover, the underlying transition trees prevent redundant replacements and permit the detection of the most probable isotopologue in a first phase. A relative threshold can then be exploited in a second parallelized phase for a precise prepruning of large fractions of the remaining subisotopologues. The gain in performance from such early pruning and the lower variation in the distortion of simulated data with use of relative rather than absolute thresholds were validated in a large-scale benchmark simulation, unprecedentedly comprising several thousand molecular formulas. Both the algorithm and a wealth of related features are freely available as R-package enviPat and as a user-friendly Web interface.
Strategies to characterize polar organic contamination in wastewater: exploring the capability of high resolution mass spectrometry
Wastewater effluents contain a multitude of organic contaminants and transformation products, which cannot be captured by target analysis alone. High accuracy, high resolution mass spectrometric data were explored with novel untargeted data processing approaches (enviMass, nontarget, and RMassBank) to complement an extensive target analysis in initial "all in one" measurements. On average 1.2% of the detected peaks from 10 Swiss wastewater treatment plant samples were assigned to target compounds, with 376 reference standards available. Corrosion inhibitors, artificial sweeteners, and pharmaceuticals exhibited the highest concentrations. After blank and noise subtraction, 70% of the peaks remained and were grouped into components; 20% of these components had adduct and/or isotope information available. An intensity-based prioritization revealed that only 4 targets were among the top 30 most intense peaks (negative mode), while 15 of these peaks contained sulfur. Of the 26 nontarget peaks, 7 were tentatively identified via suspect screening for sulfur-containing surfactants and one peak was identified and confirmed as 1,3-benzothiazole-2-sulfonate, an oxidation product of a vulcanization accelerator. High accuracy, high resolution data combined with tailor-made nontarget processing methods (all available online) provided vital information for the identification of a wider range of heteroatom-containing compounds in the environment.
Schymanski, E. L.; Singer, H. P.; Longrée, P.; Loos, M.; Ruff, M.; Stravs, M. A.; Ripollés Vidal, C.; Hollender, J. (2014) Strategies to characterize polar organic contamination in wastewater: exploring the capability of high resolution mass spectrometry, Environmental Science and Technology, 48(3), 1811-1818, doi:10.1021/es4044374, Institutional Repository
Schymanski, E. L.; Jeon, J.; Gulde, R.; Fenner, K.; Ruff, M.; Singer, H. P.; Hollender, J. (2014) Identifying small molecules via high resolution mass spectrometry: communicating confidence, Environmental Science and Technology, 48(4), 2097-2098, doi:10.1021/es5002105, Institutional Repository
How a complete pesticide screening changes the assessment of surface water quality
A comprehensive assessment of pesticides in surface waters is challenging due to the large number of potential contaminants. Most scientific studies and routine monitoring programs include only 15–40 pesticides, which leads to error-prone interpretations. In the present study, an extensive analytical screening was carried out using liquid chromatography–high-resolution mass spectrometry, covering 86% of all polar organic pesticides sold in Switzerland and applied to agricultural or urban land (in total 249 compounds), plus 134 transformation products; each of which could be quantified in the low ng/L range. Five medium-sized rivers, containing large areas of diverse crops and urban settlements within the respective catchments, were sampled between March and July 2012. More than 100 parent compounds and 40 transformation products were detected in total, between 30 and 50 parent compounds in each two-week composite sample in concentrations up to 1500 ng/L. The sum of pesticide concentrations was above 1000 ng/L in 78% of samples. The chronic environmental quality standard was exceeded for 19 single substances; using a mixture toxicity approach, exceedances occurred over the whole measurement period in all rivers. With scenario calculations including only 30–40 frequently measured pesticides, the number of detected substances and the mixture toxicity would be underestimated on average by a factor of 2. Thus, selecting a subset of substances to assess the surface water quality may be sufficient, but a comprehensive screening yields substantially more confidence.
Moschet, C.; Wittmer, I.; Simovic, J.; Junghans, M.; Piazzoli, A.; Singer, H.; Stamm, C.; Leu, C.; Hollender, J. (2014) How a complete pesticide screening changes the assessment of surface water quality, Environmental Science and Technology, 48(10), 5423-5432, doi:10.1021/es500371t, Institutional Repository
Exploring the behaviour of emerging contaminants in the water cycle using the capabilities of high resolution mass spectrometry
To characterize a broad range of organic contaminants and their transformation products (TPs) as well as their loads, input pathways and fate in the water cycle, the Department of Environmental Chemistry (Uchem) at Eawag applies and develops high-performance liquid chromatography (LC) methods combined with high-resolution tandem mass spectrometry (HRMS/MS). In this article, the background and state-of-the-art of LC-HRMS/MS for detection of i) known targets, ii) suspected compounds like TPs, and iii) unknown emerging compounds are introduced briefly. Examples for each approach are taken from recent research projects conducted within the department. These include the detection of trace organic contaminants and their TPs in wastewater, pesticides and their TPs in surface water, identification of new TPs in laboratory degradation studies and ozonation experiments and finally the screening for unknown compounds in the catchment of the river Rhine.
Hollender, J.; Bourgin, M.; Fenner, K. B.; Longrée, P.; Mcardell, C. S.; Moschet, C.; Ruff, M.; Schymanski, E. L.; Singer, H. P. (2014) Exploring the behaviour of emerging contaminants in the water cycle using the capabilities of high resolution mass spectrometry, Chimia, 68(11), 793-798, doi:10.2533/chimia.2014.793, Institutional Repository
Alleviating the reference standard dilemma using a systematic exact mass suspect screening approach with liquid chromatography-high resolution mass spectrometry
In this study, the efficiency of a suspect screening strategy using liquid chromatography-high resolution mass spectrometry (LC-HRMS) without the prior purchase of reference standards was systematically optimized and evaluated for assessing the exposure of rarely investigated pesticides and their transformation products (TPs) in 76 surface water samples. Water-soluble and readily ionizable (electrospray ionization) substances, 185 in total, were selected from a list of all insecticides and fungicides registered in Switzerland and their major TPs. Initially, a solid phase extraction-LC-HRMS method was established using 45 known, persistent, and high sales volume pesticides. Seventy percent of these target substances had limit of quantitation (LOQ) < 5 ng L–1. This compound set was then used to develop and optimize a HRMS suspect screening method using only the exact mass as a priori information. Thresholds for blank subtraction, peak area, peak shape, signal-to-noise, and isotopic pattern were applied to automatically filter the initially picked peaks. The success rate was 70%; false negatives mainly resulted from low intense peaks. The optimized approach was applied to the remaining 140 substances. Nineteen additional substances were detected in environmental samples, two TPs for the first time in the environment. Sixteen substances were confirmed with reference standards purchased subsequently, while three TP standards could be obtained from industry or other laboratories. Overall, this screening approach was fast and very successful and can easily be expanded to other micropollutant classes for which reference standards are not readily accessible such as TPs of household chemicals.
Moschet, C.; Piazzoli, A.; Singer, H.; Hollender, J. (2013) Alleviating the reference standard dilemma using a systematic exact mass suspect screening approach with liquid chromatography-high resolution mass spectrometry, Analytical Chemistry, 85(21), 10312-10320, doi:10.1021/ac4021598, Institutional Repository
Multi-level approach for the integrated assessment of polar organic micropollutants in an international lake catchment: The example of Lake Constance
Polar organic micropollutants (MPs) can have ecotoxicological effects on aquatic ecosystems and their occurrence in drinking water is a threat to public health. An extensive exposure assessment of MPs in large river and lake catchments is a necessary but challenging proposition for researchers and regulators. To get a complete picture of MP exposure in a large catchment, we employed a novel integrated strategy including MP measurement in the international catchment of Lake Constance and mass-flux modeling. A comprehensive screening of 252 MPs in the lake water by high-resolution mass spectrometry was used to identify the most commonly present MPs for the study site. It was found that the wastewater borne MPs diclofenac, carbamazepine, sulfamethoxazole, acesulfame, sucralose, benzotriazole, and methylbenzotriazole accounted for the most frequent and prominent findings. The concentration pattern of these compounds in the catchment was calculated based on regionalized inputs from wastewater treatment plants (WWTPs) and substance specific elimination rates. In 52, 8, and 3 of the 112 investigated river locations the concentration exceeded the predicted no-effect levels for diclofenac, sulfamethoxazole and carbamazepine, respectively. By coupling the catchment and lake model the effect of future trends in usage as well as possible mitigation options were evaluated for the tributaries and the lake. The upgrade of the major WWTPs in the catchment with a postozonation step would lead to a load reduction between 32% and 52% for all substances except for sucralose (10%).
Moschet, C.; Götz, C.; Longrée, P.; Hollender, J.; Singer, H. (2013) Multi-level approach for the integrated assessment of polar organic micropollutants in an international lake catchment: The example of Lake Constance, Environmental Science and Technology, 47(13), 7028-7036, doi:10.1021/es304484w, Institutional Repository
Multiresidue analysis of 88 polar organic micropollutants in ground, surface and wastewater using online mixed-bed multilayer solid-phase extraction coupled to high performance liquid chromatography-tandem mass spectrometry
An automated multiresidue method consisting of an online solid-phase extraction step coupled to a high performance liquid chromatography–tandem mass spectrometer (online-SPE–HPLC–MS/MS method) was developed for the determination of 88 polar organic micropollutants with a broad range of physicochemical properties (log DOW (pH 7): −4.2 to 4.2). Based on theoretical considerations, a single mixed-bed multilayer cartridge containing four different extraction materials was composed for the automated enrichment of water samples. This allowed the simultaneous analysis of pesticides, biocides, pharmaceuticals, corrosion inhibitors, many of their transformation products, and the artificial sweetener sucralose in three matrices groundwater, surface water, and wastewater. Limits of quantification (LOQs) were in the environmentally relevant concentration range of 0.1–87 ng/L for groundwater and surface water, and 1.5–206 ng/L for wastewater. The majority of the compounds could be quantified below 10 ng/L in groundwater (82%) and surface water (80%) and below 100 ng/L in wastewater (80%). Relative recoveries were largely between 80 and 120%. Intraday and inter-day precision, expressed as relative standard deviation, were generally better than 10% and 20%, respectively. 50 isotope labeled internal standards were used for quantification and accordingly, relative recoveries as well as intraday and inter-day precision were better for compounds with corresponding internal standard. The applicability of this method was shown during a sampling campaign at a riverbank filtration site for drinking water production with travel times of up to 5 days. 36 substances of all compound classes investigated could be found in concentrations between 0.1 and 600 ng/L. The results revealed the persistence of carbamazepine and sucralose in the groundwater aquifer as well as degradation of the metamizole metabolite 4-acetamidoantipyrine.
Huntscha, S.; Singer, H. P.; McArdell, C. S.; Frank, C. E.; Hollender, J. (2012) Multiresidue analysis of 88 polar organic micropollutants in ground, surface and wastewater using online mixed-bed multilayer solid-phase extraction coupled to high performance liquid chromatography-tandem mass spectrometry, Journal of Chromatography A, 1268, 74-83, doi:10.1016/j.chroma.2012.10.032, Institutional Repository
Exploring industrial discharges of polar organic contaminants to Swiss surface waters
High resolution mass spectrometry in the field
Comprehensive monitoring of organic trace substances in surface waters is time-consuming and costly. The NAWA SPEZ project delivers data and analyses on the status of water pollution.
In order to obtain a more comprehensive picture of the contamination of Swiss groundwater with polar organic micropollutants...
The screening of aquatic systems for known and unknown polar and semi-polar organic micropollutants relies heavily on analytical chemistry, foremost high-resolution mass spectrometry (HRMS) coupled to liquid chromatography (LC)....
The river Rhine and its tributaries are a source of drinking water for more than 20 million people. At the same time treated waste water from numerous industrial sites and from the 54 million people living in the catchment area ends up in the rivers...