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Johannes Ranke
Scientific Consultant, 79639 Grenzach-Wyhlen, Germany

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Journal article
Published: 28 July 2021 in Environments
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When data on the degradation of a chemical substance have been collected in a number of environmental media (e.g., in different soils), two strategies can be followed for data evaluation. Currently, each individual dataset is evaluated separately, and representative degradation parameters are obtained by calculating averages of the kinetic parameters. However, such averages often take on unrealistic values if certain degradation parameters are ill-defined in some of the datasets. Moreover, the most appropriate degradation model is selected for each individual dataset, which is time consuming and then requires workarounds for averaging parameters from different models. Therefore, a simultaneous evaluation of all available data is desirable. If the environmental media are viewed as random samples from a population, an advanced strategy based on assumptions about the statistical distribution of the kinetic parameters across the population can be used. Here, we show the advantages of such simultaneous evaluations based on nonlinear mixed-effects models that incorporate such assumptions in the evaluation process. The advantages of this approach are demonstrated using synthetically generated data with known statistical properties and using publicly available experimental degradation data on two pesticidal active substances.

ACS Style

Johannes Ranke; Janina Wöltjen; Jana Schmidt; Emmanuelle Comets. Taking Kinetic Evaluations of Degradation Data to the Next Level with Nonlinear Mixed-Effects Models. Environments 2021, 8, 71 .

AMA Style

Johannes Ranke, Janina Wöltjen, Jana Schmidt, Emmanuelle Comets. Taking Kinetic Evaluations of Degradation Data to the Next Level with Nonlinear Mixed-Effects Models. Environments. 2021; 8 (8):71.

Chicago/Turabian Style

Johannes Ranke; Janina Wöltjen; Jana Schmidt; Emmanuelle Comets. 2021. "Taking Kinetic Evaluations of Degradation Data to the Next Level with Nonlinear Mixed-Effects Models." Environments 8, no. 8: 71.

Journal article
Published: 10 December 2019 in Environments
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In the kinetic evaluation of chemical degradation data, degradation models are fitted to the data by varying degradation model parameters to obtain the best possible fit. Today, constant variance of the deviations of the observed data from the model is frequently assumed (error model “constant variance”). Allowing for a different variance for each observed variable (“variance by variable”) has been shown to be a useful refinement. On the other hand, experience gained in analytical chemistry shows that the absolute magnitude of the analytical error often increases with the magnitude of the observed value, which can be explained by an error component which is proportional to the true value. Therefore, kinetic evaluations of chemical degradation data using a two-component error model with a constant component (absolute error) and a component increasing with the observed values (relative error) are newly proposed here as a third possibility. In order to check which of the three error models is most adequate, they have been used in the evaluation of datasets obtained from pesticide evaluation dossiers published by the European Food Safety Authority (EFSA). For quantitative comparisons of the fits, the Akaike information criterion (AIC) was used, as the commonly used error level defined by the FOrum for the Coordination of pesticide fate models and their USe(FOCUS) is based on the assumption of constant variance. A set of fitting routines was developed within the mkin software package that allow for robust fitting of all three error models. Comparisons using parent only degradation datasets, as well as datasets with the formation and decline of transformation products showed that in many cases, the two-component error model proposed here provides the most adequate description of the error structure. While it was confirmed that the variance by variable error model often provides an improved representation of the error structure in kinetic fits with metabolites, it could be shown that in many cases, the two-component error model leads to a further improvement. In addition, it can be applied to parent only fits, potentially improving the accuracy of the fit towards the end of the decline curve, where concentration levels are lower.

ACS Style

Johannes Ranke; Stefan Meinecke. Error Models for the Kinetic Evaluation of Chemical Degradation Data. Environments 2019, 6, 124 .

AMA Style

Johannes Ranke, Stefan Meinecke. Error Models for the Kinetic Evaluation of Chemical Degradation Data. Environments. 2019; 6 (12):124.

Chicago/Turabian Style

Johannes Ranke; Stefan Meinecke. 2019. "Error Models for the Kinetic Evaluation of Chemical Degradation Data." Environments 6, no. 12: 124.

Journal article
Published: 18 May 2018 in Environmental Sciences Europe
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For evaluating the fate of xenobiotics in the environment, a variety of degradation or environmental metabolism experiments are routinely conducted. The data generated in such experiments are evaluated by optimizing the parameters of kinetic models in a way that the model simulation fits the data. No comparison of the main software tools currently in use has been published to date. This article shows a comparison of numerical results as well as an overall, somewhat subjective comparison based on a scoring system using a set of criteria. The scoring was separately performed for two types of uses. Uses of type I are routine evaluations involving standard kinetic models and up to three metabolites in a single compartment. Evaluations involving non-standard model components, more than three metabolites or more than a single compartment belong to use type II. For use type I, usability is most important, while the flexibility of the model definition is most important for use type II. Test datasets were assembled that can be used to compare the numerical results for different software tools. These datasets can also be used to ensure that no unintended or erroneous behaviour is introduced in newer versions. In the comparison of numerical results, good agreement between the parameter estimates was observed for datasets with up to three metabolites. For the now unmaintained reference software DegKinManager/ModelMaker, and for OpenModel which is still under development, user options were identified that should be taken care of in order to obtain results that are as reliable as possible. Based on the scoring system mentioned above, the software tools gmkin, KinGUII and CAKE received the best scores for use type I. Out of the 15 software packages compared with respect to use type II, again gmkin and KinGUII were the first two, followed by the script based tool mkin, which is the technical basis for gmkin, and by OpenModel. Based on the evaluation using the system of criteria mentioned above and the comparison of numerical results for the suite of test datasets, the software tools gmkin, KinGUII and CAKE are recommended for use type I, and gmkin and KinGUII for use type II. For users that prefer to work with scripts instead of graphical user interfaces, mkin is recommended. For future software evaluations, it is recommended to include a measure for the total time that a typical user needs for a kinetic evaluation into the scoring scheme. It is the hope of the authors that the publication of test data, source code and overall rankings foster the evolution of useful and reliable software in the field.

ACS Style

Johannes Ranke; Janina Wöltjen; Stefan Meinecke. Comparison of software tools for kinetic evaluation of chemical degradation data. Environmental Sciences Europe 2018, 30, 1 -12.

AMA Style

Johannes Ranke, Janina Wöltjen, Stefan Meinecke. Comparison of software tools for kinetic evaluation of chemical degradation data. Environmental Sciences Europe. 2018; 30 (1):1-12.

Chicago/Turabian Style

Johannes Ranke; Janina Wöltjen; Stefan Meinecke. 2018. "Comparison of software tools for kinetic evaluation of chemical degradation data." Environmental Sciences Europe 30, no. 1: 1-12.

Journal article
Published: 21 May 2014 in ChemPhysChem
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The molecular interaction potentials, including S (dipolarity/polarizability), A (hydrogen bonding acidity), and B (hydrogen bonding basicity), of anions are experimentally determined using multi-functionalized stationary phases in high-performance liquid chromatography (HPLC) systems. We employ three different multi-functionalized stationary phase columns (Obelisc R, Obelisc N, and Acclaim Trinity-P1) combined with two ingredients, namely, acetonitrile (ACN) and methanol (MeOH). These conditions can cause neutral, cationic, and anionic compounds to be retained. By using the retention characteristics of calibration compounds, including cations, anions, and neutral compounds, system parameters including the ionic interaction terms (zc Zc , za Za ) are evaluated using multiple linear regression, resulting in a standard deviation (SD) of 0.090-0.158 log units. Based on the system parameters and retention characteristics of the anions of interest, their molecular interaction potentials are characterized on the same scale for neutral and cationic molecules. Furthermore, to verify the determined molecular interaction potentials, we predict anion hydrophobicity. The results show that the determined S, A, and B, together with the computable descriptors E (excess molar refraction) and V (McGowan volume), can predict anion hydrophobicity with R(2) =0.982 and SD=0.167 (dimensionless).

ACS Style

Chul-Woong Cho; Stefan Stolte; Johannes Ranke; Ulrich Preiss; Ingo Krossing; Jorg Thöming. Quantitative Analysis of Molecular Interaction Potentials of Ionic Liquid Anions Using Multi-Functionalized Stationary Phases in HPLC. ChemPhysChem 2014, 15, 2351 -2358.

AMA Style

Chul-Woong Cho, Stefan Stolte, Johannes Ranke, Ulrich Preiss, Ingo Krossing, Jorg Thöming. Quantitative Analysis of Molecular Interaction Potentials of Ionic Liquid Anions Using Multi-Functionalized Stationary Phases in HPLC. ChemPhysChem. 2014; 15 (11):2351-2358.

Chicago/Turabian Style

Chul-Woong Cho; Stefan Stolte; Johannes Ranke; Ulrich Preiss; Ingo Krossing; Jorg Thöming. 2014. "Quantitative Analysis of Molecular Interaction Potentials of Ionic Liquid Anions Using Multi-Functionalized Stationary Phases in HPLC." ChemPhysChem 15, no. 11: 2351-2358.

Articles
Published: 29 August 2013 in SAR and QSAR in Environmental Research
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In this study we present prediction models for estimating in silico the cationic hydrophobicity and the cytotoxicity (log [1/EC50]) of ionic liquids (ILs) towards the Leukemia rat cell line (IPC-81), the marine bacterium Vibrio fischeri and the limnic green algae Scenedesmus vacuolatus using linear free energy relationship (LFER) descriptors computed by COSMO calculations. The LFER descriptors used for the prediction model (i.e. excess molar refraction (E), dipolarity/polarizability (S), hydrogen-bonding acidity (A), hydrogen-bonding basicity (B) and McGowan volume (V)) were calculated using sub-descriptors (sig2, sig3, HBD3, HBA4, MR, and volume) derived from COSMO–RS, COSMO and OBPROP. With the combination of two solute descriptors (B, V) of the cation we were able to predict cationic hydrophobicity values (log ko) with r 2 = 0.987 and standard error (SE) = 0.139 log units. By using the calculated log k o values, we were able to deduce a linear toxicity prediction model. In the second prediction study for the cytotoxicity of ILs, analysis of descriptor sensitivity helped us to determine that the McGowan volume (V) terms of the cation was the most important predictor of cytotoxicity and to simplify prediction models for cytotoxicity of ILs towards the IPC-81 (r 2 of 0.778, SE of 0.450 log units), Vibrio fischeri (r 2 of 0.762, SE of 0.529 log units) and Scenedesmus vacuolatus (r 2 of 0.776, SE of 0.825 log units). The robustness and predictivity of the two models for IPC-81 and Vibrio fischeri were checked by comparing the calculated SE and r 2 (coefficient of determination) values of the test set.

ACS Style

C.-W. Cho; Johannes Ranke; J. Arning; Jorg Thöming; U. Preiss; C. Jungnickel; M. Diedenhofen; Ingo Krossing; Stefan Stolte. In silicomodelling for predicting the cationic hydrophobicity and cytotoxicity of ionic liquids towards theLeukemiarat cell line,Vibrio fischeriandScenedesmus vacuolatusbased on molecular interaction potentials of ions. SAR and QSAR in Environmental Research 2013, 24, 863 -882.

AMA Style

C.-W. Cho, Johannes Ranke, J. Arning, Jorg Thöming, U. Preiss, C. Jungnickel, M. Diedenhofen, Ingo Krossing, Stefan Stolte. In silicomodelling for predicting the cationic hydrophobicity and cytotoxicity of ionic liquids towards theLeukemiarat cell line,Vibrio fischeriandScenedesmus vacuolatusbased on molecular interaction potentials of ions. SAR and QSAR in Environmental Research. 2013; 24 (10):863-882.

Chicago/Turabian Style

C.-W. Cho; Johannes Ranke; J. Arning; Jorg Thöming; U. Preiss; C. Jungnickel; M. Diedenhofen; Ingo Krossing; Stefan Stolte. 2013. "In silicomodelling for predicting the cationic hydrophobicity and cytotoxicity of ionic liquids towards theLeukemiarat cell line,Vibrio fischeriandScenedesmus vacuolatusbased on molecular interaction potentials of ions." SAR and QSAR in Environmental Research 24, no. 10: 863-882.

Journal article
Published: 27 January 2012 in ChemPhysChem
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In order to understand molecular interaction potentials of 30 cations of ionic liquids (ILs), the well-known linear free energy relationship concept (LFER) was applied. The LFER descriptors for the excess molar refractivity and the molar volume were calculated in silico and for hydrogen-bonding acidity and basicity, and the polarizability/dipolarity of IL cations were experimentally determined through high performance liquid chromatography (HPLC) measurements. For the study, three different columns (RP-select B, Cyan, and Diol) and buffered mobile phases, based on two organic solvents acetonitrile (ACN) and methanol (MeOH), were selectively combined to the HPLC separation systems RP-select B-ACN, RP-select B-MeOH, Cyan-MeOH, Diol-ACN, and Diol-MeOH. By measuring the retention factors of 45 neutral calibration compounds and calculating LFER descriptors of three cations in the HPLC systems, the system parameters, including an ionic z coefficient, were determined. Conversely, the LFER descriptors of 30 ionic liquid cations were determined, based on the parameters of five systems and their retention factors in the HPLC systems. The results showed that the type of head group, alkyl chain length and further substituents of the cation have a significant influence on the dipolarity/polarizability and the hydrogen-bonding acidity, and functionalized groups (hydroxyl, ether, and dimethylamino) lead to hydrogen-bonding basicity of the cation. The characterization of cationic LFER descriptors opens up the chance for a more quantitative understanding of molecular interaction potentials and physicochemical properties of ILs.

ACS Style

Chul-Woong Cho; Christian Jungnickel; Stefan Stolte; Ulrich Preiss; Jürgen Arning; Johannes Ranke; Ingo Krossing; Jorg Thöming. Determination of LFER Descriptors of 30 Cations of Ionic Liquids-Progress in Understanding Their Molecular Interaction Potentials. ChemPhysChem 2012, 13, 780 -787.

AMA Style

Chul-Woong Cho, Christian Jungnickel, Stefan Stolte, Ulrich Preiss, Jürgen Arning, Johannes Ranke, Ingo Krossing, Jorg Thöming. Determination of LFER Descriptors of 30 Cations of Ionic Liquids-Progress in Understanding Their Molecular Interaction Potentials. ChemPhysChem. 2012; 13 (3):780-787.

Chicago/Turabian Style

Chul-Woong Cho; Christian Jungnickel; Stefan Stolte; Ulrich Preiss; Jürgen Arning; Johannes Ranke; Ingo Krossing; Jorg Thöming. 2012. "Determination of LFER Descriptors of 30 Cations of Ionic Liquids-Progress in Understanding Their Molecular Interaction Potentials." ChemPhysChem 13, no. 3: 780-787.

Journal article
Published: 19 May 2011 in The Journal of Physical Chemistry B
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In this article, we present evolutionary models to predict the octanol-water partition coefficients (log P), water solubilities, and critical micelle concentrations (CMCs) of ionic liquids (ILs), as well as the anionic activity coefficients and hydrophobicities in pure water and octanol-water. They are based on a polyparameter linear free energy relationship (LFER) using measured and/or DFT-calculated LFER parameters: hydrogen-bonding acidity (A), hydrogen-bonding basicity (B), polarizability/dipolarity (S), excess molar refraction (E), and McGowan volume (V) of IL ions. With both calculated or experimental LFER descriptors of IL ions, the physicochemical parameters were predicted with an errors of 0.182-0.217 for the octanol-water partition coefficient and 0.131-0.166 logarithmic units for the water solubility. Because experimentally determined solute parameters of anions are not currently available, the CMC, anionic activity coefficient, and hydrophobicity were predicted with quantum-chemical methods with R(2) values of at least 0.99, as well as errors below 0.168 logarithmic units. These new approaches will facilitate the assessment of the technical applicability and environmental fate of ionic compounds even before their synthesis.

ACS Style

Chul-Woong Cho; Ulrich Preiss; Christian Jungnickel; Stefan Stolte; Jürgen Arning; Johannes Ranke; Andreas Klamt; Ingo Krossing; Jorg Thöming. Ionic Liquids: Predictions of Physicochemical Properties with Experimental and/or DFT-Calculated LFER Parameters To Understand Molecular Interactions in Solution. The Journal of Physical Chemistry B 2011, 115, 6040 -6050.

AMA Style

Chul-Woong Cho, Ulrich Preiss, Christian Jungnickel, Stefan Stolte, Jürgen Arning, Johannes Ranke, Andreas Klamt, Ingo Krossing, Jorg Thöming. Ionic Liquids: Predictions of Physicochemical Properties with Experimental and/or DFT-Calculated LFER Parameters To Understand Molecular Interactions in Solution. The Journal of Physical Chemistry B. 2011; 115 (19):6040-6050.

Chicago/Turabian Style

Chul-Woong Cho; Ulrich Preiss; Christian Jungnickel; Stefan Stolte; Jürgen Arning; Johannes Ranke; Andreas Klamt; Ingo Krossing; Jorg Thöming. 2011. "Ionic Liquids: Predictions of Physicochemical Properties with Experimental and/or DFT-Calculated LFER Parameters To Understand Molecular Interactions in Solution." The Journal of Physical Chemistry B 115, no. 19: 6040-6050.

Reference entry
Published: 15 July 2010 in Handbook of Green Chemistry
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The sections in this article areIntroductionThe T‐SAR Approach and the “Test Kit” ConceptStrategy for the Design of Sustainable Ionic Liquids(Eco)toxicity of Ionic LiquidsInfluence of the Side ChainInfluence of the Head GroupInfluence of the AnionToxicity of Ionic Liquids as a Function of the Surrounding MediumCombination Effects(Quantitative) Structure–Activity Relationships and Modes of Toxic ActionConclusionBiodegradability of Ionic LiquidsIntroductionTesting of BiodegradabilityResults from Biodegradation ExperimentsBiodegradability of Ionic Liquid AnionsBiodegradability of Imidazolium CompoundsPyridinium and 4‐(Dimethylamino)pyridinium CompoundsBiodegradability of Other Head GroupsMisleading Interpretation of Biodegradation DataMetabolic Pathways of Ionic Liquid CationsAbiotic DegradationOutlookConclusionToxicity and (Eco)toxicity of Ionic LiquidsBiodegradability of Ionic LiquidsThe Goal Conflict in Designing Sustainable Ionic LiquidsFinal RemarksKeywords:ionic liquids;safety;biodegradation;toxicology;ecotoxicity;green chemistry

ACS Style

Marianne Matzke; Jürgen Arning; Johannes Ranke; Bernd Jastorff; Stefan Stolte. Design of Inherently Safer Ionic Liquids: Toxicology and Biodegradation. Handbook of Green Chemistry 2010, 1 .

AMA Style

Marianne Matzke, Jürgen Arning, Johannes Ranke, Bernd Jastorff, Stefan Stolte. Design of Inherently Safer Ionic Liquids: Toxicology and Biodegradation. Handbook of Green Chemistry. 2010; ():1.

Chicago/Turabian Style

Marianne Matzke; Jürgen Arning; Johannes Ranke; Bernd Jastorff; Stefan Stolte. 2010. "Design of Inherently Safer Ionic Liquids: Toxicology and Biodegradation." Handbook of Green Chemistry , no. : 1.

Journal article
Published: 23 November 2009 in Chemical Research in Toxicology
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To demonstrate how baseline toxicity can be separated from other more specific modes of toxic action and to address possible pitfals when dealing with hydrophobic substances, the four isothiazol-3-one biocides N-methylisothiazol-3-one (MIT), 5-chloro-N-methylisothiazol-3-one (CIT), N-octylisothiazol-3-one (OIT), and 4,5-dichloro-N-octylisothiazol-3-one (DCOIT) as an example for reactive electrophilic xenobiotics were tested for their cytotoxic effects on the human hepatoblastoma cell line Hep G2, on the marine bacterium Vibrio fischeri, and on the limnic green alga Scenedesmus vacuolatus. In each of the three test systems, toxic effects were observed in a consistent pattern. The two chlorinated compounds and OIT were found to be significantly more toxic than MIT. As compared to baseline toxicants, the small and polar MIT and CIT exhibited pronounced excess toxicity in each of the three test systems that is presumably triggered by their intrinsic reactivity toward cellular thiols. In contrast, OIT and DCOIT showed mainly toxicities that could be explained by their hydrophobicity. Analyzing and comparing these results using the toxic ratio concept and with data that indicate a dramatic depletion of cellular glutathione levels after incubation with DCOIT reveals that for highly hydrophobic substances, baseline level toxicity in an assay for acute toxicity can lead to an oversight of other more specific modes of toxic action that may cause significant effects that might be less reversible than those caused by unreactive baseline toxicants. This possibility should be taken into account in the hazard assessment of chemicals that are both hydrophobic and reactive.

ACS Style

Jürgen Arning; Marianne Matzke; Stefan Stolte; Frauke Nehen; Ulrike Bottin-Weber; Andrea Böschen; Salha Abdulkarim; Bernd Jastorff; Johannes Ranke. Analyzing Cytotoxic Effects of Selected Isothiazol-3-one Biocides Using the Toxic Ratio Concept and Structure−Activity Relationship Considerations. Chemical Research in Toxicology 2009, 22, 1954 -1961.

AMA Style

Jürgen Arning, Marianne Matzke, Stefan Stolte, Frauke Nehen, Ulrike Bottin-Weber, Andrea Böschen, Salha Abdulkarim, Bernd Jastorff, Johannes Ranke. Analyzing Cytotoxic Effects of Selected Isothiazol-3-one Biocides Using the Toxic Ratio Concept and Structure−Activity Relationship Considerations. Chemical Research in Toxicology. 2009; 22 (12):1954-1961.

Chicago/Turabian Style

Jürgen Arning; Marianne Matzke; Stefan Stolte; Frauke Nehen; Ulrike Bottin-Weber; Andrea Böschen; Salha Abdulkarim; Bernd Jastorff; Johannes Ranke. 2009. "Analyzing Cytotoxic Effects of Selected Isothiazol-3-one Biocides Using the Toxic Ratio Concept and Structure−Activity Relationship Considerations." Chemical Research in Toxicology 22, no. 12: 1954-1961.

Journal article
Published: 18 March 2009 in International Journal of Molecular Sciences
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The water solubility of salts is ordinarily dictated by lattice energy and ion solvation. However, in the case of low melting salts also known as ionic liquids, lattice energy is immaterial and differences in hydrophobicity largely account for differences in their water solubility. In this contribution, the activity coefficients of ionic liquids in water are split into cation and anion contributions by regression against cation hydrophobicity parameters that are experimentally determined by reversed phase liquid chromatography. In this way, anion hydrophobicity parameters are derived, as well as an equation to estimate water solubilities for cation-anion combinations for which the water solubility has not been measured. Thus, a new pathway to the quantification of aqueous ion solvation is shown, making use of the relative weakness of interactions between ionic liquid ions as compared to their hydrophobicities.

ACS Style

Johannes Ranke; Alaa Othman; Ping Fan; Anja Müller. Explaining Ionic Liquid Water Solubility in Terms of Cation and Anion Hydrophobicity. International Journal of Molecular Sciences 2009, 10, 1271 -1289.

AMA Style

Johannes Ranke, Alaa Othman, Ping Fan, Anja Müller. Explaining Ionic Liquid Water Solubility in Terms of Cation and Anion Hydrophobicity. International Journal of Molecular Sciences. 2009; 10 (3):1271-1289.

Chicago/Turabian Style

Johannes Ranke; Alaa Othman; Ping Fan; Anja Müller. 2009. "Explaining Ionic Liquid Water Solubility in Terms of Cation and Anion Hydrophobicity." International Journal of Molecular Sciences 10, no. 3: 1271-1289.

Journals
Published: 18 September 2008 in Green Chemistry
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In the last decade, ionic liquids have shown great promise in a plethora of applications. However, little attention has been paid to the characterisation of the purity of these fluids, which has ultimately led to non-reproducible data in the literature. In order to facilitate specification of ionic liquids, a number of analytical protocols with their limits of detection (where available) have been compiled, including methods of other authors. In particular, quantitative methods have been developed and summarised for the determination of the total ionic liquid content, residual unreacted ionic liquid starting material and by-products (amines, alkylating agents, inorganic halides), solvents from extraction procedures and water, in addition to decomposition products and total volatiles.

ACS Style

Annegret Stark; Peter Behrend; Oliver Braun; Anja Müller; Johannes Ranke; Bernd Ondruschka; Bernd Jastorff. Purity specification methods for ionic liquids. Green Chemistry 2008, 10, 1152 -1161.

AMA Style

Annegret Stark, Peter Behrend, Oliver Braun, Anja Müller, Johannes Ranke, Bernd Ondruschka, Bernd Jastorff. Purity specification methods for ionic liquids. Green Chemistry. 2008; 10 (11):1152-1161.

Chicago/Turabian Style

Annegret Stark; Peter Behrend; Oliver Braun; Anja Müller; Johannes Ranke; Bernd Ondruschka; Bernd Jastorff. 2008. "Purity specification methods for ionic liquids." Green Chemistry 10, no. 11: 1152-1161.

Journal article
Published: 01 July 2008 in Journal of Chemical Education
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ACS Style

Marco Eissen; Müfit Bahadir; Burkhard König; Johannes Ranke. Developing and Disseminating NOP: An Online, Open-Access, Organic Chemistry Teaching Resource To Integrate Sustainability Concepts in the Laboratory. Journal of Chemical Education 2008, 85, 1 .

AMA Style

Marco Eissen, Müfit Bahadir, Burkhard König, Johannes Ranke. Developing and Disseminating NOP: An Online, Open-Access, Organic Chemistry Teaching Resource To Integrate Sustainability Concepts in the Laboratory. Journal of Chemical Education. 2008; 85 (7):1.

Chicago/Turabian Style

Marco Eissen; Müfit Bahadir; Burkhard König; Johannes Ranke. 2008. "Developing and Disseminating NOP: An Online, Open-Access, Organic Chemistry Teaching Resource To Integrate Sustainability Concepts in the Laboratory." Journal of Chemical Education 85, no. 7: 1.

Journal article
Published: 01 July 2008 in Basic and Applied Ecology
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Certain substances may be hazardous to ecosystems. To be able to preserve the structures and functions of ecosystems, knowledge is required to qualify and quantify such hazards. To this end, biotests are indispensable tools. For the development and/or choice of biotests, special attention has to be drawn to conflicts between scientific demands and practical constraints. From a purely scientific point of view, experiments should be designed to maximise the ecological relevance of the obtained results. However, this often collides with the limited resources (budget, time, manpower) available. Furthermore, societal issues (e.g. animal welfare) have to be taken into account. Thus, it is necessary to develop a scientifically sound testing approach that avoids unnecessary animal testing, keeps the costs low, and can be performed within a short timeframe. The different perspectives of ecology, environmental toxicology, and environmental chemistry should be integrated into a balanced ecotoxicological approach. Accordingly, we propose a dynamic testing strategy, which is adapted to the substance (or substance group) in question and its mode(s) of action. Bestimmte chemische Substanzen können eine Gefahr für Ökosysteme darstellen. Für den Schutz der Strukturen und Funktionen in Ökosystemen, müssen diese Gefahren qualifiziert und quantifiziert werden. Biotests liefern dafür die entscheidenden Ergebnisse. Für die Entwicklung und/oder Wahl solcher Biotests, muss den Konflikten zwischen wissenschaftlichen Ansprüchen und praktischen Beschränkungen besondere Aufmerksamkeit geschenkt werden. Aus rein wissenschaftlicher Sicht sollten die Experimente so gestaltet sein, dass die ökologische Relevanz der Ergebnisse maximiert wird. Dies stösst jedoch häufig an die Grenzen der verfügbaren Ressourcen (Budget, Zeit, Arbeitskraft). Zusätzlich müssen gesellschaftliche Aspekte berücksichtigt werde (z.B. der Tierschutz). Daher ist es notwendig, einen wissenschaftlich stimmigen Test-Ansatz zu wählen, der unnötige Tierversuche vermeidet, die Kosten gering hält und innerhalb kurzer Zeit durchgeführt werden kann. Die unterschiedlichen Aspekte von Ökologie, Umwelttoxikologie und Umweltchemie sollten zu einem ausgewogenen ökotoxikologischen Ansatz zusammengeführt werden. Daher schlagen wir eine dynamische Teststrategie vor, welche sich an die jeweilige Substanz (oder Substanzgruppe) und ihre Wirkmechanismen anpasst.

ACS Style

Marion Junghans; Maike Schaefer; Wiebke Drost; Enken Hassold; Frauke Stock; Matthias Dünne; Tanja Juffernholz; Wiebke Meyer; Johannes Ranke. Reconsidering environmental effects assessment of chemicals: Proposal for a dynamic testing strategy. Basic and Applied Ecology 2008, 9, 356 -364.

AMA Style

Marion Junghans, Maike Schaefer, Wiebke Drost, Enken Hassold, Frauke Stock, Matthias Dünne, Tanja Juffernholz, Wiebke Meyer, Johannes Ranke. Reconsidering environmental effects assessment of chemicals: Proposal for a dynamic testing strategy. Basic and Applied Ecology. 2008; 9 (4):356-364.

Chicago/Turabian Style

Marion Junghans; Maike Schaefer; Wiebke Drost; Enken Hassold; Frauke Stock; Matthias Dünne; Tanja Juffernholz; Wiebke Meyer; Johannes Ranke. 2008. "Reconsidering environmental effects assessment of chemicals: Proposal for a dynamic testing strategy." Basic and Applied Ecology 9, no. 4: 356-364.

Journal article
Published: 01 May 2008 in Environmental Science and Pollution Research
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Many surface coatings, including roof paints, contain biocides. It is generally not known to what extent roof paint biocides leach from the paint, and consequently, what concentration the biocide may attain in a rainwater collection system. To this end the leaching of specific biocides from a variety of German roof paints was investigated and the resulting concentrations in collected rain water were estimated. A laboratory simulation was used to determine the time dependant leaching rate of the biocide from the paint into synthetic rainwater. The concentrations of biocide in the leachate were quantified using HPLC. The course of the leachate concentrations over time was fitted using a simple mathematical model. This was then used to estimate concentrations of biocides in a typical household rainwater collection system over time. Surprisingly, the biocides found in the paints did not always concur with the declared biocides. Concerning the modelling of runoff concentrations, it was found that--under the model assumptions--the rain intensity and cumulative raining time after application are the dominant factors influencing the concentration of the biocide. At the highest modelled rain intensity of 40 mm/hour it only takes about 2 hours to reach peak concentrations lower than 0.1 mg/L, at 0.3 mm/hour it takes about 10 hours to reach peak concentrations of 1.3, 0.9, 5.2 and 1.1 mg/L for terbutryn from Emalux paint, terbutryn from Südwest paint, carbendazim from Emalux paint, and carbendazim from MIPA paint, respectively. The results confirm that biocides leached from roof paint will be present in roof runoff. The highest estimated peak concentrations are close to the water solubility of the respective biocides. This indicates that the model assumption of a concentration independent leaching rate will tendentially lead to an overestimation of the leached concentrations under these circumstances. However, under most circumstances such as higher rain intensities, and longer time after peak concentrations have been reached, the runoff concentrations are far from the solubility limit, and therefore it is proposed that the model assumptions are tenable. The leaching of biocides from roof paints can be roughly assessed using a relatively simple approach. The declaration of biocidal ingredients in roof paints should be improved and information on their biocide leaching behaviour should be made available. Furthermore, the estimations should be evaluated by a field study. The leaching study indicated that the concentrations of selected biocides can reach significant levels, especially after low intensity rainfall. Taking into account the inherent biological activity of the substances under scrutiny, it can already be concluded that it is not advisable to use runoff water from roofs freshly painted with biocide containing roof paints. These results have been complemented by a literature search of biological effects of the investigated biocides, ecotoxicological tests with several species and a risk analysis for organisms exposed to runoff water. This will be presented in Part 2 of this contribution.

ACS Style

Christian Jungnickel; Frauke Stock; Thomas Brandsch; Johannes Ranke. Risk assessment of biocides in roof paint. Environmental Science and Pollution Research 2008, 15, 258 -265.

AMA Style

Christian Jungnickel, Frauke Stock, Thomas Brandsch, Johannes Ranke. Risk assessment of biocides in roof paint. Environmental Science and Pollution Research. 2008; 15 (3):258-265.

Chicago/Turabian Style

Christian Jungnickel; Frauke Stock; Thomas Brandsch; Johannes Ranke. 2008. "Risk assessment of biocides in roof paint." Environmental Science and Pollution Research 15, no. 3: 258-265.

Journal article
Published: 18 April 2008 in Toxicology
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To investigate the toxic mode of action of isothiazol-3-one biocides the four compounds N-methylisothiazol-3-one (MIT), 5-chloro-N-methylisothiazol-3-one (CIT), N-octylisothiazol-3-one (OIT) and 4,5-dichloro-N-octylisothiazol-3-one (DCOIT) were purified and tested as single chemical entities for their effects on the human hepatoblastoma cell line Hep G2 and on isolated and cellular glutathione reductase GR). The two chlorinated substances CIT and DCOIT significantly decreased the amount of total cellular glutathione (GSx) in a dose and time dependent manner. Concomitantly, an increase in the level of oxidised glutathione (GSSG) was observed. The resulting shift in the GSH/GSSG ratio entailing the breakdown of the cellular thiol reduction potential was accompanied by necrotic morphological changes like swelling of the plasma membrane and subsequent lysis of the cells. Additionally, CIT and DCOIT were found to inhibit cellular GR in the cells in a concentration dependent manner. The T-SAR-based (thinking in terms of structure–activity relationships) comparison of the chlorine-substituted structures CIT and DCOIT with their non-chlorinated and less active analogues MIT and OIT identified the chlorine substituents and the resulting reaction mechanisms to be the key structural mediators of the observed toxic effects. Furthermore, differences in the activity of both chlorinated substances could be explained using the T-SAR approach to link the lipophilicity and the intrinsic glutathione-reactivity of the compounds to the expected target site concentrations inside the cells.

ACS Style

Jürgen Arning; Ralf Dringen; Maike Schmidt; Anette Thiessen; Stefan Stolte; Marianne Matzke; Ulrike Bottin-Weber; Birgit Caesar-Geertz; Bernd Jastorff; Johannes Ranke. Structure–activity relationships for the impact of selected isothiazol-3-one biocides on glutathione metabolism and glutathione reductase of the human liver cell line Hep G2. Toxicology 2008, 246, 203 -212.

AMA Style

Jürgen Arning, Ralf Dringen, Maike Schmidt, Anette Thiessen, Stefan Stolte, Marianne Matzke, Ulrike Bottin-Weber, Birgit Caesar-Geertz, Bernd Jastorff, Johannes Ranke. Structure–activity relationships for the impact of selected isothiazol-3-one biocides on glutathione metabolism and glutathione reductase of the human liver cell line Hep G2. Toxicology. 2008; 246 (2-3):203-212.

Chicago/Turabian Style

Jürgen Arning; Ralf Dringen; Maike Schmidt; Anette Thiessen; Stefan Stolte; Marianne Matzke; Ulrike Bottin-Weber; Birgit Caesar-Geertz; Bernd Jastorff; Johannes Ranke. 2008. "Structure–activity relationships for the impact of selected isothiazol-3-one biocides on glutathione metabolism and glutathione reductase of the human liver cell line Hep G2." Toxicology 246, no. 2-3: 203-212.

Book chapter
Published: 20 March 2008 in Multiphase Homogeneous Catalysis
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ACS Style

Johannes Ranke; Frauke Stock; Reinhold Störmann; Kerstin Mölter; Jens Hoffmann; Bernd Ondruschka; Bernd Jastorff. Preliminary (Eco-)Toxicological Risk Profiles of Ionic Liquids. Multiphase Homogeneous Catalysis 2008, 588 -600.

AMA Style

Johannes Ranke, Frauke Stock, Reinhold Störmann, Kerstin Mölter, Jens Hoffmann, Bernd Ondruschka, Bernd Jastorff. Preliminary (Eco-)Toxicological Risk Profiles of Ionic Liquids. Multiphase Homogeneous Catalysis. 2008; ():588-600.

Chicago/Turabian Style

Johannes Ranke; Frauke Stock; Reinhold Störmann; Kerstin Mölter; Jens Hoffmann; Bernd Ondruschka; Bernd Jastorff. 2008. "Preliminary (Eco-)Toxicological Risk Profiles of Ionic Liquids." Multiphase Homogeneous Catalysis , no. : 588-600.

Journal article
Published: 11 March 2008 in ChemInform
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Stefan Stolte; Marianne Matzke; Juergen Arning; Andrea Boeschen; William-R. Pitner; Urs Welz-Biermann; Bernd Jastorff; Johannes Ranke. ChemInform Abstract: Effects of Different Head Groups and Functionalized Side Chains on the Aquatic Toxicity of Ionic Liquids. ChemInform 2008, 39, 1 .

AMA Style

Stefan Stolte, Marianne Matzke, Juergen Arning, Andrea Boeschen, William-R. Pitner, Urs Welz-Biermann, Bernd Jastorff, Johannes Ranke. ChemInform Abstract: Effects of Different Head Groups and Functionalized Side Chains on the Aquatic Toxicity of Ionic Liquids. ChemInform. 2008; 39 (11):1.

Chicago/Turabian Style

Stefan Stolte; Marianne Matzke; Juergen Arning; Andrea Boeschen; William-R. Pitner; Urs Welz-Biermann; Bernd Jastorff; Johannes Ranke. 2008. "ChemInform Abstract: Effects of Different Head Groups and Functionalized Side Chains on the Aquatic Toxicity of Ionic Liquids." ChemInform 39, no. 11: 1.

Journal article
Published: 05 March 2008 in Colloids and Surfaces A: Physicochemical and Engineering Aspects
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Ionic liquids (ILs) form a new class of compounds with a much varied industrial and technological application. Some research has been conducted in ecotoxicity of these compounds, but very little is known about their structure in aqueous solutions. It is known that some ionic liquids can form aggregates in aqueous solution. To determine how such structures influence the use, distribution and toxicity of ILs, first the critical micelle concentrations of the ILs need to be determined. Therefore the critical micelle concentration (CMC) for a number of imidazolium ionic liquids was determined in aqueous solution. The expected dependency of the CMC on the length of the alkyl chain of the investigated 1-alkyl-3-methylimidazolium ILs was shown. The degree of ionization and the energy of aggregation were calculated and related to the alkyl chain length of the imidazolium. A significant correlation between retention times in reversed phase gradient HPLC, and the pCMC was observed. It was also shown that the CMC is directly related to the lipophilicity of the cation.

ACS Style

Christian Jungnickel; Justyna Łuczak; Johannes Ranke; José F. Fernández; Anja Müller; Jorg Thöming. Micelle formation of imidazolium ionic liquids in aqueous solution. Colloids and Surfaces A: Physicochemical and Engineering Aspects 2008, 316, 278 -284.

AMA Style

Christian Jungnickel, Justyna Łuczak, Johannes Ranke, José F. Fernández, Anja Müller, Jorg Thöming. Micelle formation of imidazolium ionic liquids in aqueous solution. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2008; 316 (1-3):278-284.

Chicago/Turabian Style

Christian Jungnickel; Justyna Łuczak; Johannes Ranke; José F. Fernández; Anja Müller; Jorg Thöming. 2008. "Micelle formation of imidazolium ionic liquids in aqueous solution." Colloids and Surfaces A: Physicochemical and Engineering Aspects 316, no. 1-3: 278-284.

Journals
Published: 01 January 2008 in Green Chemistry
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To contribute to a deeper insight into the hazard potential of ionic liquids to humans and the environment, an acetylcholinesterase (AchE) inhibition screening assay was used to identify toxicophore substructures and interaction potentials mediating enzyme inhibition.The positively charged nitrogen atom, a widely delocalised aromatic system, and the lipophilicity of the side chains connected to the cationic head groups can be identified as the key structural elements in binding to the enzymes active site. With respect to this, the dimethylaminopyridinium, the quinolinium and the pyridinium head groups exhibit a very strong inhibitory potential to the enzyme with IC50 values around 10 µM. In contrast, the polar and non-aromatic morpholinium head group is found to be only weakly inhibiting to the enzyme activity, with IC50 values > 500 µM.The introduction of polar hydroxy, ether or nitrile functions into the alkyl side chain is shown to be a potent structural alteration to shift the corresponding ionic liquids to a lower inhibitory potential. Supporting this fact, for a series of imidazolium cations, a QSAR correlation was set up by the linear regression of the log IC50versus the logarithm of the HPLC-derived lipophilicity parameter k0.Additionally, a broad set of anion species (inorganic, organic and complex borate anions), commonly used as ionic liquid counterions, was tested and the vast majority exhibited no effect on AchE. Only the fluoride and fluoride containing anion species which readily undergo hydrolytic cleavage can be identified to act as AchE inhibitors.

ACS Style

Jürgen Arning; Stefan Stolte; Andrea Böschen; Frauke Stock; William-Robert Pitner; Urs Welz-Biermann; Bernd Jastorff; Johannes Ranke. Qualitative and quantitative structure activity relationships for the inhibitory effects of cationic head groups, functionalised side chains and anions of ionic liquids on acetylcholinesterase. Green Chemistry 2008, 10, 47 -58.

AMA Style

Jürgen Arning, Stefan Stolte, Andrea Böschen, Frauke Stock, William-Robert Pitner, Urs Welz-Biermann, Bernd Jastorff, Johannes Ranke. Qualitative and quantitative structure activity relationships for the inhibitory effects of cationic head groups, functionalised side chains and anions of ionic liquids on acetylcholinesterase. Green Chemistry. 2008; 10 (1):47-58.

Chicago/Turabian Style

Jürgen Arning; Stefan Stolte; Andrea Böschen; Frauke Stock; William-Robert Pitner; Urs Welz-Biermann; Bernd Jastorff; Johannes Ranke. 2008. "Qualitative and quantitative structure activity relationships for the inhibitory effects of cationic head groups, functionalised side chains and anions of ionic liquids on acetylcholinesterase." Green Chemistry 10, no. 1: 47-58.

Journals
Published: 27 November 2007 in Green Chemistry
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We investigated the primary biodegradation of different N-imidazoles, imidazolium, pyridinium and 4-(dimethylamino)pyridinium compounds substituted with various alkyl side chains and their analogues containing functional groups principally based on OECD guideline 301 D. For the experiments we used two different types of inocula, a freeze-dried mix of bacteria and activated sludge microorganisms from a wastewater treatment plant. The aim of this study was to improve the knowledge base for the structural design of ionic liquids with respect to an increased biodegradability combined with a reduced (eco)toxicological hazard potential. We found a significant primary biodegradation for (eco)toxicologically unfavourable compounds carrying long alkyl side chains (C6 and C8). In contrast for (eco)toxicologically more recommendable imidazolium ionic liquids with short alkyl (⩽C6) and short functionalised side chains, no biological degradation could be found. The introduction of different functional groups into the side chain moiety thus offering a higher chemical reactivity did not lead to the expected improvement of the biological degradation. After an incubation period of 24 days for the 1-methyl-3-octylimidazolium cation we identified different biological transformation products carrying hydroxyl, carbonyl and carboxyl groups. Furthermore, shortened side chain moieties were identified indicating the degradation of the octyl side chain via β-oxidation. Moreover, we propose an electrochemical wastewater treatment as part of an alternative disposal strategy for non-biodegradable ionic liquids. We show for the first time that the 1-butyl-3-methylimidazolium cation was completely destroyed within four hours using an electrolysis double-cell (volume = 1.2 L) equipped with electrodes made of iridium oxide (anode), stainless steel (cathode), and a boron-doped diamond-coated bipolar electrode. The products formed electrochemically were easily accessible to biological degradation.

ACS Style

Stefan Stolte; Salha Abdulkarim; Jürgen Arning; Anne-Katrin Blomeyer-Nienstedt; Ulrike Bottin-Weber; Marianne Matzke; Johannes Ranke; Bernd Jastorff; Jorg Thöming. Primary biodegradation of ionic liquid cations, identification of degradation products of 1-methyl-3-octylimidazolium chloride and electrochemical wastewater treatment of poorly biodegradable compounds. Green Chemistry 2007, 10, 214 -224.

AMA Style

Stefan Stolte, Salha Abdulkarim, Jürgen Arning, Anne-Katrin Blomeyer-Nienstedt, Ulrike Bottin-Weber, Marianne Matzke, Johannes Ranke, Bernd Jastorff, Jorg Thöming. Primary biodegradation of ionic liquid cations, identification of degradation products of 1-methyl-3-octylimidazolium chloride and electrochemical wastewater treatment of poorly biodegradable compounds. Green Chemistry. 2007; 10 (2):214-224.

Chicago/Turabian Style

Stefan Stolte; Salha Abdulkarim; Jürgen Arning; Anne-Katrin Blomeyer-Nienstedt; Ulrike Bottin-Weber; Marianne Matzke; Johannes Ranke; Bernd Jastorff; Jorg Thöming. 2007. "Primary biodegradation of ionic liquid cations, identification of degradation products of 1-methyl-3-octylimidazolium chloride and electrochemical wastewater treatment of poorly biodegradable compounds." Green Chemistry 10, no. 2: 214-224.