Unknown Transformation Products Research Articles

Review of an up-to-date, emphatic, and concise perspective on e-cigarettes

Electronic cigarettes entered the market in 2007 as an alternative to conventional tobacco products, and their use has increased significantly worldwide. Due to the emergence of various harmful effects and attracting attention, their sale was banned in our country and many other countries. However, according to the research, the use of e-cigarettes is increasing rapidly in the world and in Türkiye, and the rate of use at young ages is quite high especially. Its supply can be easily made through online sales on many websites. Despite this growing popularity, little is known about the potential effects of e-cigarettes on human health. This is particularly important in the presence of flavoring compounds, solvents, additives, and other ingredients that are added intentionally or unintentionally and whose long-term effects are uncertain. This is because every day a new product with new ingredients, flavors, and properties is introduced to the market. Previous studies have focused on measuring known toxicants, particularly those found in traditional cigarettes, while fewer have investigated unknown compounds and transformation products formed during the e-cigarette process in these diverse and ever-evolving products. It seems that the e-cigarette market is growing and developing rapidly in our country, as in the whole world, and product sales continue to increase despite all kinds of bans. However, when we look at the literature, the research conducted is insufficient, as mentioned above, and there are points that need to be further emphasized.

Screening and identification of unknown chemical contaminants in food based on liquid chromatography–high-resolution mass spectrometry and machine learning

Unknown or unexpected chemical contaminants and/or their transformation products in food that may be harmful to humans need to be discovered for comprehensive safety evaluation. Liquid chromatography–high-resolution mass spectrometry (LC-HRMS) is a powerful tool for detecting chemical contaminants in food samples. However, identifying all of peaks in LC-HRMS is not possible, but if class information is known in advance, further identification will become easier. In this work, a novel MS2 spectra classification-driven screening strategy was constructed based on LC-HRMS and machine learning. First, the classification model was developed based on machine learning algorithm using class information and experimental MS2 data of chemical contaminants and other non-contaminants. By using the developed artificial neural network classification model, in total 32 classes of pesticides, veterinary drugs and mycotoxins were classified with good prediction accuracy and low false-positive rate. Based on the classification model, a screening procedure was developed in which the classes of unknown features in LC-HRMS were first predicted through the classification model, and then their structures were identified under the guidance of class information. Finally, the developed strategy was tentatively applied to the analysis of pork and aquatic products, and 8 chemical contaminants and 11 transformation products belonging to 8 classes were found. This strategy enables screening of unknown chemical contaminants and transformation products in complex food matrices.

Uptake and metabolization of four sartan drugs by eight different plants: Targeted and untargeted analyses by HPLC-drift-tube-ion-mobility quadrupole time-of-flight mass spectrometry.

In this study, we investigated the uptake and metabolization of four drugs (plus the associated prodrugs) from the sartan family by eight edible plants. Growing the plants hydroponically in a medium containing the respective drug, more than 40 phases I and II metabolites derived from the four sartan drugs could be tentatively identified. To demonstrate the suitability of the proposed analytical approach for actual environmental samples, garden cress (Lepidium sativum) selected as a model plant was grown in water drawn from the effluent of two local wastewater treatment plants. Thereby, three of the sartans, namely, olmesartan, candesartan, and valsartan, could be found in the plant extracts at concentrations of 3.1, 10.4, and 14.4ngg-1 , respectively. Additionally, for candesartan and valsartan, a glycosylated transformation product could be detected. In order to extend the present (targeted) workflow also toward the analysis of unknown transformation products (i.e., those not listed in the custom-made database used for this research), a nontargeted approach for the analysis of plant extracts with respect to the presence of drug-related metabolites was developed. Comparison of the targeted and the nontargeted workflows led to the finding of two additional, so far unidentified, transformation products originating from azilsartan.

Photo-assisted transformation of furosemide: Exploring transformation pathways, structure database and suspect and non-target workflows for comprehensive screening of unknown transformation products in wastewaters and landfill leachates

In recent years, transformation products-(TPs) of pharmaceuticals in the environment have received considerable attention. In this context, here, a customized overview of transformation of Furosemide-(FRS) in aqueous matrices treated by photo-oxidation is provided as a proof of concept. Hence, the primary goal of the study was to display an integrated strategy by combining the target (parent-molecule) and suspect screening-(SS) approaches (TPs) in order to build an in-house High-Resolution mass spectrometry (HRMS) database able to provide reference information (chromatographic/spectral) for environmental investigations in complex matrices (wastewaters/landfill leachates). Data analysis was performed by optimizing a SS workflow. Additional confirmation for the proposed structural elucidation was provided by correlating retention time to the proposed structure employing three prediction models. This approach was applied for the tentative identification of 35 TPs of FRS, 28 of which are reported herein for the first time. Finally, SS and non-target analysis (NTA) have been successfully applied for retrospective screening of FRS and its TPs in real samples. The findings demonstrated that SS allows the proper identification of TPs of FRS in complex matrices proving its outstanding importance compared to NTA. In total, six TPs were identified by SS with potential ecotoxicological implications for two of them according to in silico risk assessment.

Electrochemistry-mass spectrometry bridging the gap between suspect and target screening of valsartan transformation products in wastewater treatment plant effluent

Degradation of xenobiotics in wastewater treatment plants may lead to the formation of transformation products with higher persistence or increased (eco-)toxic potential compared to the parent compounds. Accordingly, the identification of transformation products from wastewater treatment plant effluents has gained increasing attention. Here, we show the potential of electrochemistry hyphenated to liquid chromatography and mass spectrometry for the prediction of oxidative degradation in wastewater treatment plants using the antihypertensive drug valsartan as a model compound. This approach identifies seven electrochemical transformation products of valsartan, which are used to conduct a suspect screening in effluent of the main wastewater treatment plant in the city of Münster in Germany. Apart from the parent compound valsartan, an electrochemically predicted transformation product, the N-dealkylated ETP336, is detected in wastewater treatment plant effluent. Subsequently, a targeted liquid chromatographytandem mass spectrometry method for the detection of valsartan and its electrochemical transformation products is set up. Here, electrochemical oxidation is used to generate reference materials of the transformation products in situ by hyphenating electrochemistry online to a triple quadrupole mass spectrometer. Using this setup, multiple reaction monitoring transitions are set up without the need for laborious and costly synthesis and isolation of reference materials for the transformation products. The targeted method is then applied to extracts from wastewater treatment plant effluent and the presence of ETP336 and valsartan in the samples is verified. The presented workflow can be used to set up targeted analysis methods for previously unknown transformation products even without the need for expensive high-resolution mass spectrometers.

New hydrolysis products of oxytetracycline and their contribution to hard COD in biological effluents of antibiotic production wastewater

With the increasing demand for stringent discharge regulations, the efficient removal of non-biodegradable organic (hard COD) from the biological effluent of pharmaceutical wastewater is becoming increasingly important. Enhanced hydrolysis pretreatment has been used to remove antibiotic potency in antibiotic production wastewater before biological treatment, while the resulting transformation products (TPs) and their contribution to hard COD are largely unknown. Herein, we combine target and non-target analysis aiming to find the major oxytetracycline (OTC) TPs after enhanced hydrolysis pretreatment and to quantify their contribution to the hard COD in biological effluents. Three literature-known and 15 yet unknown TPs, most of which could not be biodegraded, were identified during lab-scale hydrolysis of OTC under neutral conditions. Nuclear magnetic resonance and combined density functional theory were used to determine and infer the molecular structures and possible hydrolysis pathways of them. Furthermore, two stable and dominant TPs, M390s (M390-1 and M390-2), were separated, purified, and structurally identified, which could account for 21.0% and 14.9% − 20.4% (molar ratio) of the initial OTC in the lab-scale and field studies, respectively. More importantly, M390s account for 4.5–––7.8% of the hard COD in biological effluents. The results indicate that the contribution of antibiotic TPs to hard COD in wastewater could not be ignored, and provide more knowledge regarding the efficient treatment of antibiotic production wastewater.

Non-targeted screening of emerging contaminants in South African surface and wastewater

Targeted analysis of contaminants in water are often focused on a narrow range of chemicals, falling short of the true pollution status of water bodies. Non targeted screening presents several advantages in identifying less prioritized pollutants, entirely unknown compounds and transformation products. In this study we employed a non-targeted screening workflow established on a high-resolution quadrupole time-of-flight mass spectrometer coupled to an ultrahigh performance liquid chromatograph (UHPLC-QTOF-MS) to identify known and unknown pollutants in South African waste and surface waters. Level two confidence identification of 315 compounds was achieved based on mass accuracy, isotope patterns and MS/MS spectra match. Pharmaceuticals, drugs, and metabolites made up 40% of the detected compounds, biological compounds and industrial chemicals along with their metabolites constituted 24 and 18% respectively, while personal care products, pesticides and food additives made up approximately 5, 4 and 4% respectively. Several antiretroviral drugs were confirmed with level one confidence using isotope labelled standards. A wide range of “new” pharmaceuticals, pesticides and metabolites were documented in South African waters for the first time. Seventeen (17) pharmaceuticals were reported for the first time in South African waters, of which four are reported for the first time ever in surface water.The result of this exploratory study highlights the presence of several contaminants of public health concern that have hitherto received little to no attention in previous wastewater-based epidemiological studies. We provide a detailed list of priority contaminants for future studies on targeted-analysis.

Identification, occurrence, concentration and composition profile of fiproles in municipal wastewater treatment plants

Although fipronil and several of its transformation products are ubiquitous in aquatic environments, limited information is available on the structural identities, detection frequencies, concentrations and composition profiles of fiproles (fipronil and its known and unknown transformation products) in municipal wastewater treatment plants (WWTPs). In this study, a suspect screening analysis was applied to identify and characterize fipronil transformation products in 16 municipal WWTPs from three cities in China. In addition to fipronil and its four transformation products (fipronil amide, fipronil sulfide, fipronil sulfone and desulfinyl fipronil), fipronil chloramine and fipronil sulfone chloramine were detected for the first time in municipal wastewater. Moreover, the cumulative concentrations of six transformation products were 0.236 ng/L and 3.44 ng/L in wastewater influents and effluents, and accounted for one-third (in influents) to half (in effluents) of fiproles. Of those transformation products, two chlorinated byproducts (fipronil chloramine and fipronil sulfone chloramine) were major transformation products in both municipal wastewater influents and effluents. Notably, the log Kow and bioconcentration factor (evaluated by EPI Suite software) of fipronil chloramine (log Kow = 6.64, and BCF = 11,200 L/kg wet-wt) and fipronil sulfone chloramine (log Kow = 4.42, and BCF = 382.9 L/kg wet-wt) were greater than that of their parent compound. Considering the persistence, bioaccumulation potential and toxicity, the high detection rates of fipronil chloramine and fipronil sulfone chloramine in urban aquatic systems need to be specifically considered in future ecological risk assessments.

Intelligent Workflow and Software for Non-Target Analysis of Complex Samples Using a Mixture of Toxic Transformation Products of Unsymmetrical Dimethylhydrazine as an Example.

Unsymmetrical dimethylhydrazine (UDMH) is a widely used rocket propellant. Entering the environment or being stored in uncontrolled conditions, UDMH easily forms an enormous variety (at least many dozens) of transformation products. Environmental pollution by UDMH and its transformation products is a major problem in many countries and across the Arctic region. Unfortunately, previous works often use only electron ionization mass spectrometry with a library search, or they consider only the molecular formula to propose the structures of new products. This is quite an unreliable approach. It was demonstrated that a newly proposed artificial intelligence-based workflow allows for the proposal of structures of UDMH transformation products with a greater degree of certainty. The presented free and open-source software with a convenient graphical user interface facilitates the non-target analysis of industrial samples. It has bundled machine learning models for the prediction of retention indices and mass spectra. A critical analysis of whether a combination of several methods of chromatography and mass spectrometry allows us to elucidate the structure of an unknown UDMH transformation product was provided. It was demonstrated that the use of gas chromatographic retention indices for two stationary phases (polar and non-polar) allows for the rejection of false candidates in many cases when only one retention index is not enough. The structures of five previously unknown UDMH transformation products were proposed, and four previously proposed structures were refined.

Mechanistic investigation of phosphonate photolysis in aqueous solution by simultaneous LC-IRMS and HRMS analysis

The mechanism of photolytic degradation of aminotrimethylphosphonic acid (ATMP) in an aqueous solution is not completely elucidated with respect to the transformation products formed during technical photodegradation. For the first time, the degradation of ATMP was investigated with simultaneous analysis by isotope ratio and high-resolution mass spectrometry (LC-IRMS+HRMS). This instrumental coupling combines quantitative data on degradation with compound-specific stable carbon isotope analysis (CSIA) in terms of kinetic isotope effects while identifying transformation products. Additionally, in combination with wet chemical analysis of ortho-phosphate (o-PO4), phosphorus balances were established to elucidate and interpret the degradation mechanism of ATMP under photolysis. Various experimental conditions during photolysis (temperature, dissolved oxygen concentration, and wavelength range) were investigated.ATMP was transformed to iminodimethylphosphonic acid (IDMP), aminomethylphosphonic acid (AMPA), and o-PO4 as main products during photolysis with a medium pressure mercury lamp. UV radiation < 310 nm was found to be required for ATMP degradation. The degradation of ATMP and its transformation products is slightly affected by temperature and dissolved oxygen concentration. Considering possible reactive oxygen species, such as hydroxyl radicals, it is assumed that the degradation of ATMP occurs to a small extent via a parallel degradation pathway in addition to photolysis. Complementary CSIA revealed an inverse carbon isotopic effect of ATMP due to direct photolysis, unaffected by the experimental conditions considered, while no isotopic effect was associated with the hydroxyl radical (H2O2) oxidation of ATMP. In UV/H2O2 oxidation of ATMP, four of five additional unknown transformation products, which have not yet been described in literature, could be assigned to postulated structures based on HRMS data. The findings achieved in this study demonstrate the advantages of simultaneous analysis by LC-IRMS+HRMS as a tool to elucidate reaction mechanisms for the first time.

Comparative efficiency of oxidation processes to remove acesulfame in water treatment plants supplied by surface water sources

Abstract The effects of oxidizing agents during water treatment on the concentration of an artificial sweetener were evaluated in full-scale conditions. Five drinking water treatment plants (DWTPs) located in a northern environment with high seasonal variations which use different raw water sources and different combinations of oxidants (ozone, chlorine, UV radiation) were investigated through the removal of the artificial sweetener acesulfame (ACE) along their treatment chains. In total, 98 sampling campaigns were conducted at these DWTPs. Raw water (impacted by variable tidal and hydrodynamic conditions), partially treated water within the DWTPs, and fully treated drinking water were sampled during eight months over the period of higher variability of source water quality. Results showed ACE concentrations in raw waters vary on a seasonal basis: higher in winter and summer (when rivers have low water discharges) and lower during spring and fall. Multi-barrier treatment systems under study were effective for the removal of acesulfame due specifically to the effect of ozone and chlorine during oxidation steps, while no removal was observed using physico-chemical (coagulation flocculation, filtration) and UV treatments. Depending on the number of treatment steps that involved ozonation or chlorination and the position of these oxidative processes in the treatment chain, removal of ACE varied from 24% to 90% in the plants under study. The results indicate that increasing oxidant doses would result in better removal of ACE and other contaminants, but these strategies must consider unknown transformation products, potentially with greater toxicological effects than their precursors.

Enhanced database creation with in silico workflows for suspect screening of unknown tebuconazole transformation products in environmental samples by UHPLC-HRMS

The search and identification of organic contaminants in agricultural watersheds has become a crucial effort to better characterize watershed contamination by pesticides. The past decade has brought a more holistic view of watershed contamination via the deployment of powerful analytical strategies such as non-target and suspect screening analysis that can search more contaminants and their transformation products. However, suspect screening analysis remains broadly confined to known molecules, primarily due to the lack of analytical standards and suspect databases for unknowns such as pesticide transformation products. Here we developed a novel workflow by cross-comparing the results of various in silico prediction tools against literature data to create an enhanced database for suspect screening of pesticide transformation products. This workflow was applied on tebuconazole, used here as a model pesticide, and resulted in a suspect screening database counting 291 transformation products. The chromatographic retention times and tandem mass spectra were predicted for each of these compounds using 6 models based on multilinear regression and more complex machine-learning algorithms. This comprehensive approach to the investigation and identification of tebuconazole transformation products was retrospectively applied on environmental samples and found 6 transformation products identified for the first time in river water samples.

Machine learning-assisted non-target analysis of a highly complex mixture of possible toxic unsymmetrical dimethylhydrazine transformation products with chromatography-mass spectrometry

Unsymmetrical dimethylhydrazine (UDMH) is a toxic and environmentally hostile compound that was massively introduced to the environment during previous decades due to its use in the space and rocket industry. The compound forms multiple transformation products, and many of them are as dangerous as UDMH or even more dangerous. The danger includes, but is not limited to, acute toxicity, chronic health hazards, carcinogenicity, and environmental damage. UDMH transformation products are poorly investigated. In this work, the mixture formed by long storage of the waste that contained UDMH was studied. Even a preliminary screening of such a mixture is a complex task. It consists of dozens of compounds, and most of them are missing in chemical and spectral databases. The complete preparative separation of such a mixture is very laborious. We applied several methods of gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry, and several machine learning and chemoinformatics methods to make a preliminary but informative screening of the mixture. Machine learning allowed predicting retention indices and mass spectra of candidate structures. The combination of various ion sources and a comparison of the observed with the predicted spectra and retention was used to propose confident structures for 24 compounds. It was demonstrated that neither high-resolution mass spectrometry nor mass spectral library matching is enough to elucidate the structures of unknown UDMH transformation products. At the same time, the use of machine learning and a combination of methods significantly improves the identification power. Finally, machine learning was applied to estimate the acute toxicity of the discovered compounds. It was shown that many of them are comparable to or even more toxic than UDMH itself. Such an extremely wide and still underestimated variety of easily formed derivatives of UDMH can lead to a significant underestimation of the potential hazard of this compound.

Enhanced Database Creation with in Silico Workflows for Suspect Screening of Unknown Pesticide Transformation Products in Environmental Samples by Uhplc-Hrms

Enhanced Database Creation with in Silico Workflows for Suspect Screening of Unknown Pesticide Transformation Products in Environmental Samples by Uhplc-Hrms

Assessing the influence of pig slurry pH on the degradation of selected antibiotic compounds

Veterinary medicines are routinely used in animal husbandry and the environment may consequently be exposed to them via manure applications. This presents potential environmental and societal risks such as toxicological effects to aquatic/terrestrial organisms and the spread of antimicrobial resistance. Regulatory studies that assess the degradability of veterinary antibiotics during manure storage currently permit the use of just one manure per animal type although we speculate that heterogenic properties such as pH could be driving significant variability within degradation rates. To bridge this knowledge gap and assess degradation variability with pH, laboratory degradation studies were performed on a broad range of antibiotics (ceftiofur, florfenicol, oxytetracycline, sulfamethoxazole and tylosin) at three different environmentally relevant pH levels (5.5, 7, and 8.5). The effect of pig slurry pH on degradation rates was found to be significant and compound specific. Usually, acidic slurries were found to inhibit degradation when compared to neutral pH, for florfenicol, tylosin, and ceftiofur; the associated changes in DT50 (half-life) values were 2–209 h, 35.28–234 h, and 0.98–2.13 h, respectively. In some circumstances alkaline slurries were observed to enhance the degradation rate when compared to those for neutral pH, for tylosin, the respective changes in DT50 values were from 3.52 to 35.28 h. Comparatively, the degradation of sulfamethoxazole was enhanced by acidic conditions compared to neutral (DT50 20.6–31.6 h). Tentative identification of unknown transformation products (TPs) was achieved for sulfamethoxazole and florfenicol for the first time in pig slurries. These results reveal the importance of considering slurry pH when assessing the degradation of antibiotic compounds, which has implications for the acidification of manures and the environmental risk assessment for veterinary medicines.Environmental relevance and significance: Given the significant effect of pig slurry pH on degradation rates, manure degradation studies need to be harmonised and standardized, taking into account the influence of pH.

Characterizing the Chemical Landscape in Commercial E-Cigarette Liquids and Aerosols by Liquid Chromatography-High-Resolution Mass Spectrometry.

The surge in electronic cigarette (e-cig) use in recent years has raised questions on chemical exposures that may result from vaping. Previous studies have focused on measuring known toxicants, particularly those present in traditional cigarettes, while fewer have investigated unknown compounds and transformation products formed during the vaping process in these diverse and constantly evolving products. The primary aim of this work was to apply liquid chromatography-high-resolution mass spectrometry (LC-HRMS) and chemical fingerprinting techniques for the characterization of e-liquids and aerosols from a selection of popular e-cig products. We conducted nontarget and quantitative analyses of tobacco-flavored e-liquids and aerosols generated using four popular e-cig products: one disposable, two pod, and one tank/mod. Aerosols were collected using a condensation device and analyzed in solution alongside e-liquids by LC-HRMS. The number of compounds detected increased from e-liquids to aerosols in three of four commercial products, as did the proportion of condensed-hydrocarbon-like compounds, associated with combustion. Kendrick mass defect analysis suggested that some of the additional compounds detected in aerosols belonged to homologous series resulting from decomposition of high-molecular-weight compounds during vaping. Lipids in inhalable aerosols have been associated with severe respiratory effects, and lipid-like compounds were observed in aerosols as well as e-liquids analyzed. Six potentially hazardous additives and contaminants, including the industrial chemical tributylphosphine oxide and the stimulant caffeine, were identified and quantified in the e-cig liquids and aerosols analyzed. The obtained findings demonstrate the potential of nontarget LC-HRMS to identify previously unknown compounds and compound classes in e-cig liquids and aerosols, which is critical for the assessment of chemical exposures resulting from vaping.

Accumulation of Insensitive Munition Compounds in the Earthworm Eisenia andrei from Amended Soil: Methodological Considerations for Determination of Bioaccumulation Factors.

The present study investigates the bioaccumulation of the insensitive munition compounds 2,4-dinitroanisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO), developed for future weapons systems to replace current munitions containing sensitive explosives. The earthworm Eisenia andrei was exposed to sublethal concentrations of DNAN or NTO amended in Sassafras sandy loam. Chemical analysis indicated that 2- and 4-amino-nitroanisole (2-ANAN and 4-ANAN, respectively) were formed in DNAN-amended soils. The SumDNAN (sum of DNAN, 2-ANAN, and 4-ANAN concentrations) in soil decreased by 40% during the 14-d exposure period. The SumDNAN in the earthworm body residue increased until day 3 and decreased thereafter. Between days 3 and 14, there was a 73% decrease in tissue uptake that was greater than the 23% decrease in the soil concentration, suggesting that the bioavailable fraction may have decreased over time. By day 14, the DNAN concentration accounted for only 45% of the SumDNAN soil concentration, indicating substantial DNAN transformation in the presence of earthworms. The highest bioaccumulation factor (BAF; the tissue-to-soil concentration ratio) was 6.2 ± 1.0 kg/kg (dry wt) on day 3 and decreased to 3.8 ± 0.8 kg/kg by day 14. Kinetic studies indicated a BAF of 2.3 kg/kg, based on the earthworm DNAN uptake rate of 2.0 ± 0.24 kg/kg/d, compared with the SumDNAN elimination rate of 0.87 d-1 (half-life = 0.79 d). The compound DNAN has a similar potential to bioaccumulate from soil compared with trinitrotoluene. The NTO concentration in amended soil decreased by 57% from the initial concentration (837 mg NTO/kg dry soil) during 14 d, likely due to the formation of unknown transformation products. The bioaccumulation of NTO was negligible (BAF ≤ 0.018 kg/kg dry wt). Environ Toxicol Chem 2021;40:1713-1725. © 2021 SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

A strategy for an initial assessment of the ecotoxicological effects of transformation products of pesticides in aquatic systems following a tiered approach

In order to conduct a fast and comprehensive toxicity screening of pesticide transformation products (TPs), this study used a tiered approach by a combination of in silico and experimental methods to determine the probability to be of relevance for risk assessment. The six pesticides Boscalid, Penconazole, Diuron, Terbutryn, Octhilinone (OIT), and Mecoprop were used as model compounds. Identification of corresponding environmental known and unknown TPs were done by literature analysis and photolysis experiments in combination. Aquatic solutions of the pesticides were photolysed to generate TPs which can be expected in the aquatic environment. The resulting mixtures were screened for TPs by high resolution LC-MS/MS. The herein developed approach was conducted at three different tiers: Literature review and in silico methods were used to predict exemplary the environmental bacterial toxicity and the genotoxicity of every single TP at tier I. In case of indications to be toxic, experiments at tier II were applied. Hereby, the photolytic mixtures containing parent compound and TPs were used for the consecutive toxicity test. Microtox assay for the parent compounds and the photolytic mixture was conducted to determine the acute and chronic toxicity and the growth inhibition of V. fischeri. Umu-tests were conducted to determine primary DNA damage. At tier III, single substance standards were used to conduct toxicity tests in case of toxic indication by previous tiers and availability of analytical standard. Identification of TPs revealed 45 known environmental TPs that originated from the six pesticides. The number of substances that need to be assessed was therefore more than sevenfold. By the tiered approach, it was possible to assess toxicological effects on environmental bacteria of 94% of the selected TPs. For 20% we found strong evidence to be toxic to environmental bacteria, as they were assessed at least at two tiers. For further 44% of the TPs we found slight evidence, as they could be assessed at one tier. Contrary, this approach turned out to be unsuitable to assess genotoxic effects of TPs neither by in silico tools nor by experiments. The number of substances that could probably pose a risk onto environment was quadrupled in comparison to the consideration of solely the parent compounds. Thus, this study demonstrates that the conducted screening approach allows for easy and fast identification of environmental relevant TPs. However, the study presented was a very first screening. Its applicability domain needs to be assessed further. For this purpose as a very next step the approach suggested here should be verified by applying additional endpoints and including additional parent compounds.

Identification of opioids in surface and wastewaters by LC/QTOF-MS using retrospective data analysis

Opioids, both as prescription drugs and abuse substances, have been a hot topic and a focus of discussion in the media for the last few years. Although the literature published shows the occurrence of opioids and some of their metabolites in the aquatic environment, there are scarce data in the application of high resolution mass spectrometry (HRMS) for the analysis of these compounds in the environment. The use of HRMS allows increasing the number of opioids that can be studied as well as the detection of unknown opioids, their metabolites and potential transformation products. In this work, a retrospective analysis for the identification of opioids and their metabolites using a curated database was applied to surface water and wastewater samples taken in the state of Minnesota (U.S.) in 2009, which were previously analyzed by liquid chromatography/time-of-flight mass spectrometry (LC/TOF-MS) for antidepressants. The database comprised >200 opioids including natural opiates (e.g. morphine and codeine), their semi-synthetic derivatives (e.g. heroin, hydromorphone, hydrocodone, oxycodone, oxymorphone, meperidine and buprenorphine), fully synthetic opioids (e.g. fentanyl, methadone, tramadol, dextromethorphan and propoxyphene), as well as some of their metabolites (e.g. 6-monoacetylcodeine, dextrorphan, EDDP, normorphine and O-desmethyltramadol). Moreover, additional MS-MS experiments were performed to confirm their identification, as well as to recognize fragmentation patterns and diagnostic ions for several opioids. These data provide a better understanding of the historical occurrence of opioids and their metabolites in surface waters impacted by wastewater sources. The concentrations of individual opioids in surface water and wastewater effluent varied from 8.8 (EDDP) to 1640 (tramadol) ngL−1 and from 12 (dihydrocodeine) to 1288 (tramadol) ngL−1, respectively. The opioids with higher overall frequency detections were tramadol, dextromethorphan and its metabolite, dextrorphan.

Approach for analytical characterization and toxicological assessment of ozonation products in drinking water on the example of acesulfame

The monitoring and control of drinking water quality is generally important as it significantly contributes to the health of the population. In this context, particular attention has to be paid to the use of treatment techniques during drinking water treatment. It is known that the formation of reaction products (transformation products) has to be taken into account when oxidizing agents such as ozone are used. Different transformation products are classified as critical to health and require analytical examination. The risk assessment for previously unknown transformation products can be difficult as far as not all transformation products are present as single substances or the individual substances are not present in a sufficient high concentration or cannot be isolated from the original solution. The aim of this work is to show exemplarily the identification and quantification of ozonation products (OPs) after ozonation and their toxicological characterization, using the artificial sweetener acesulfame. It was shown that OPs can be fully characterized using ion chromatography in combination with different detection systems. A major OP could be recovered as a pure substance by crystallization and direct genotoxicological testing was possible without previous enrichment processes. Acesulfame samples of different concentrations in ultrapure and in drinking water after ozonation were tested in several genotoxicity tests. These tests revealed genotoxic effects of acesulfame after ozonation in ultrapure water in several genotoxicological test systems (micronucleus test, umu test, Ames-fluctuation-test and comet assay). In contrast, the crystallized ozonation product OP168 did not show any positive effects. Therefore, it seems likely that the observed effect was caused by the second major product OP170. However, a sufficiently large amount of analytically pure substance OP170 could not be obtained. It was also shown that the rate of the OP170 formation in drinking water is significantly lower than in ultrapure water and that ozonation in drinking water did not induce genotoxic effects.