Determination of the integral toxicity of water in terms of biotesting with a multisensor system sensitive to individual toxicants

Possibility of applying a multisensor potentiometric system of the type of the “electronic tongue” as a method for evaluating the toxicity of a water medium is considered. The multisensor system is preliminarily calibrated against samples with a known toxicity, determined by the biotesting method with the use of living organisms. It is shown that the thus obtained system is suitable for evaluating the quality of water samples in terms of the response of various test objects without direct use of living organisms.     

Solid-phase extraction for toxicity reduction evaluations of industrial wastewater effluents

The physical, chemical and biological characteristics of industrial and municipal wastewater effluents in the United States are limited in National Pollutant Discharge Elimination System (NPDES) permits. Toxicity reduction evaluations (TREs) involving fractionation of wastewater effluents, biomonitoring for aquatic toxicity and determinations of specific chemicals are conducted when adverse effects on water quality are detected during routine biomonitoring as required by the NPDES permit. However, certain fractionation techniques are incompatible with subsequent testing for aquatic toxicity. The effect of various schemes for fractionation of wastewater effluent on biomonitoring with freshwater Cladocerans (Daphnia magna, Daphnia pulex, Ceriodaphnia dubia or Ceriodaphnia reticulata) is reviewed. Solid-phase extraction (SPE) is discussed as a chromatographic technique used for the selective fractionation of wastewater effluents during toxicity reduction evaluation.     

Toxicity assays applied to wastewater treatment

The utility and validity of toxicity tests for monitoring of wastewater treatment have been assessed. The evaluated acute toxicity tests have been Vibrio fischeri, Selenastrum capricornotum and Daphnia magna tests. The validation studies indicated that the acute toxicity tests can be considered as high sensitivity analytical tools to detect common environmental concentrations of the pollutants at concentration levels as low as ng l⁻¹. The toxicity tests showed to have discriminatory ability to distinguish between different degrees of toxicity, and the toxic specificity of the compounds on target organisms. Synergistic, additive or antagonistic effects were evaluated indicating the capacity of the toxicity test to assess the combined effects of chemicals in wastewaters. The reproducibility of these tests, calculated as relative standard deviation, is acceptable in the range of 5-22.3%. The application of multivariate date analysis proved that toxicity and chemical measures are complementary analytical tools for monitoring of wastewaters quality. The toxicity tests are useful analytical tools for screening of chemical analysis and as an early warning system to monitor the treatment of WWTPs. The use of single toxicity test or battery of tests is the best approach to evaluate the risk because they are reliable indices of the toxic impact of effluents in the aquatic environment. The toxicity tests were applied in the quality control of different European WWTPs.     

In vitro cytotoxicity assessment based on KC50 with real-time cell analyzer (RTCA) assay

Technological advances in cytotoxicity analysis have now made it possible to obtain real time data on changes in cell growth, morphology and cell death. This type of testing has a great potential for reducing and refining traditional in vivo toxicology tests. By monitoring the dynamic response profile of living cells via the xCELLigence real-time cell analyzer for high-throughput (RTCA HT) system, cellular changes including cell number (cell index, CI) are recorded and analyzed. A special scaled index defined as normalized cell index (NCI) is used in the analysis which reduces the influence of inter-experimental variations. To assess the extent of exposure of the tested chemicals, a two-exponent model is presented to describe rate of cell growth and death. This model is embodied in the time and concentration-dependent cellular response curves, and the parameters k₁ and k₂ in this model are used to describe the rate of cell growth and death. Based on calculated k₂ values and the corresponding concentrations, a concentration–response curve is fitted. As a result, a cytotoxicity assessment named KC₅₀ is calculated. The validation of the proposed method is demonstrated by exposing six cell lines to 14 chemical compounds. Our findings suggest that the proposed KC₅₀-based toxicity assay can be an alternative to the traditional single time-point assay such as LC₅₀ (the concentration at which 50% of the cells are killed). The proposed index has a potential for routine evaluation of cytotoxicities. Another advantage of the proposed index is that it extracts cytotoxicity information when CI fails to detect the low toxicity.     

Toxicity of Nanoscale CuO and ZnO to Daphnia magna

The potential effects of nanoscale CuO(nCuO),nanoscale ZnO(nZnO)and their mixtures on Daphnia magna were investigated,including 48-h acute toxicity and 21-d chronic toxicity tests as well as a feeding ...     

Multianalyte imaging in one-shot format sensors for natural waters

A one-shot multisensor based on ionophore-chromoionophore chemistry for optical monitoring of potassium, magnesium and hardness in water is presented. The analytical procedure uses a black and white non-cooled CCD camera for image acquisition of the one-shot multisensor after reaction, followed by data treatment for quantitation using the grey value pixel average from a defined region of interest from each sensing area to build the analytical parameter 1 − α. In optimised experimental conditions, the procedure shows a large linear range, up to 6 orders using the linearised model and good detection limits: 9.92 × 10⁻⁵ mM, 1.86 × 10⁻³ mM and 1.30 × 10⁻² mg L⁻¹ of CaCO₃ for potassium, magnesium and hardness, respectively. This analysis system exhibits good precision in terms of relative standard deviation (RSD%) from 2.3 to 3.8 for potassium, from 5.0 to 6.8 for magnesium and from 5.4 to 5.9 for hardness. The trueness of this multisensor procedure was demonstrated comparing it with results obtained by a DAD spectrophotometer used as a reference. Finally, it was satisfactorily applied to the analysis of these analytes in miscellaneous samples, such as water and beverage samples from different origins, validating the results against atomic absorption spectrometry (AAS) as the reference procedure.     

Synthesis and Toxicity Evaluation of New Pyrroles Obtained by the Reaction of Activated Alkynes with 1-Methyl-3-(cyanomethyl)benzimidazolium Bromide

A series of new pyrrole derivatives were designed as chemical analogs of the 1,4-dihydropyridines drugs in order to develop future new calcium channel blockers. The new tri- and tetra-substituted N-arylpyrroles were synthesized by the one-pot reaction of 1-methyl-3-cyanomethyl benzimidazolium bromide with substituted alkynes having at least one electron-withdrawing substituent, in 1,2-epoxybutane, acting both as the solvent and reagent to generate the corresponding benzimidazolium N3-ylide. The structural characterization of the new substituted pyrroles was based on IR, NMR spectroscopy as well as on single crystal X-ray analysis. The toxicity of the new compounds was assessed on the plant cell using Triticum aestivum L. species and on the animal cell using Artemia franciscana Kellogg and Daphnia magna Straus crustaceans. The compounds showed minimal phytotoxicity on Triticum rootlets and virtually no acute toxicity on Artemia nauplii, while on Daphnia magna, it induced moderate to high toxicity, similar to nifedipine. Our research indicates that the newly synthetized pyrrole derivatives are promising molecules with biological activity and low acute toxicity.     

Comparative evaluation of the effects of pesticides in acute toxicity luminescence bioassays

Acute toxicity of pesticides in water was assessed singly and in mixtures using the responses of the luminescent bacterium Vibrio fischeri (BioTox™), the aquatic invertebrate Daphnia magna (Daphtoxkit™), and the MitoScan™ assay. The latter utilized fragmented mitochondria to enzymatically convert β-nicotinamide adenine dinucleotide (NADH) to its oxidized form, NAD⁺. The rate of the conversion being sensitive to type and concentration of toxicants. The pesticides tested were Carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate), Cyromazine (N-cyclopropyl-1,3,5-triazine-2,4,6-triamine), Fenamiphos (ethyl 4-methylthio-m-tolyl isopropylphosphoramidate), and Formetanate (3-dimethylaminomethyleneiminophenyl methylcarbamate). The toxicity bioassays were characterized in terms of relative sensitivity, reproducibility, range of the linear response, and the ability to reveal synergistic/antagonistic interactions among toxicants. The D. magna assay was the most sensitive and best able to detect toxic interactions of mixtures. Also, unlike the other assays used, the response of the daphnid system was linear over a 10-fold change in pesticide concentration. Relative to the BioTox™, the MitoScan™ was 2- to 11-fold more sensitive for the compounds and mixtures tested. The EC₅₀ reproducibility of all tests was within ±20% coefficient of variation; however, the lowest observable effect concentration (LOEC) were only reproducible to ±35% on average. Cyromazine was the least toxic of the pesticides tested. To test the predictive value of the concept of concentration addition, toxicities of binary and quaternary mixtures of four different pesticides were analyzed. Synergistic/antagonistic responses were most frequently observed in testing with D. magna. Synergistic/antagonistic effects were seen only in 25 and 50% of the cases with the BioTox™ and the MitoScan™ assays, respectively.     

Facile synthesis of poly(ionic liquid)‐bonded magnetic nanospheres as a high‐performance sorbent for the pretreatment and determination of phenolic compounds in water samples

Poly(ionic liquid)‐bonded magnetic nanospheres were easily synthesized and applied to the pretreatment and determination of phenolic compounds in water samples, which have detrimental effects on water quality and the health of living beings. The high affinity of poly(ionic liquid)s toward the target compounds as well as the magnetic behavior of Fe₃O₄ were combined in this material to provide an efficient and simple magnetic solid‐phase extraction approach. The adsorption behavior of the poly(ionic liquid)‐bonded magnetic nanospheres was examined to optimize the synthesis. Different parameters affecting the magnetic solid‐phase extraction of phenolic compounds were assessed in terms of adsorption and recovery. Under the optimal conditions, the proposed method showed excellent detection sensitivity with limits of detection in the range of 0.3–0.8 ng/mL and precision in the range of 1.2–3.3%. This method was also applied successfully to the analysis of real water samples; good spiked recoveries over the range of 82.5–99.2% were obtained.     

Physico-Chemical Properties of Inorganic NPs Influence the Absorption Rate of Aquatic Mosses Reducing Cytotoxicity on Intestinal Epithelial Barrier Model

Noble metals nanoparticles (NPs) and metal oxide NPs are widely used in different fields of application and commercial products, exposing living organisms to their potential adverse effects. Recent evidences suggest their presence in the aquifers water and consequently in drinking water. In this work, we have carefully synthesized four types of NPs, namely, silver and gold NPs (Ag NPs and Au NPs) and silica and titanium dioxide NPs (SiO₂ NPs and TiO₂ NPs) having a similar size and negatively charged surfaces. The synthesis of Ag NPs and Au NPs was carried out by colloidal route using silver nitrate (AgNO₃) and tetrachloroauric (III) acid (HAuCl₄) while SiO₂ NPs and TiO₂ NPs were achieved by ternary microemulsion and sol-gel routes, respectively. Once the characterization of NPs was carried out in order to assess their physico-chemical properties, their impact on living cells was studied. We used the human colorectal adenocarcinoma cells (Caco-2), known as the best representative intestinal epithelial barrier model to understand the effects triggered by NPs through ingestion. Then, we moved to explore how water contamination caused by NPs can be lowered by the ability of three species of aquatic moss, namely, Leptodictyum riparium, Vesicularia ferriei, and Taxiphyllum barbieri, to absorb them. The experiments were conducted using two concentrations of NPs (100 μM and 500 Μm as metal content) and two time points (24 h and 48 h), showing a capture rate dependent on the moss species and NPs type. Then, the selected moss species, able to actively capture NPs, appear as a powerful tool capable to purify water from nanostructured materials, and then, to reduce the toxicity associated to the ingestion of contaminated drinking water.     

Pyrolysis—high-resolution mass spectrometry of biological materials

In a diseased state in man or animals a change at eh molecular level might occur. A pyrolysis-high-resolution mass spectrometric method has been developed to measure these changes. The mass spectra are used as fingerprints. A similar approach is reported using low-resolution mass spectrometry. The difference between low resolution and high resolution is that the number of mass spectral lines is strongly increased and therefore also the information content. As a result, a change at the molecular level will be more pronounced in high-resolution mass spectra. As an application, the results of toxicity studies on Daphnia magna are given. The experiments were performed with paraoxon, parathion and malathion. The changes at the molecular level in Daphnia magna appear to be substance-dependent.     

Comparison of laser ablation-inductively coupled plasma-mass spectrometry and micro-X-ray fluorescence spectrometry for elemental imaging in Daphnia magna

Visualization of elemental distributions in thin sections of biological tissue is gaining importance in many disciplines of biological and medical research. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and scanning micro-X-ray fluorescence spectrometry (micro-XRF) are two widely used microanalytical techniques for elemental mapping. This article compares the capabilities of the two techniques for imaging the distribution of selected elements in the model organism Daphnia magna in terms of detection power and spatial resolution. Sections with a thickness of 10 and 20 μm of the fresh water crustacean Daphnia magna were subjected to LA-ICP-MS and micro-XRF analysis. The elemental distributions obtained for Ca, P, S and Zn allow element-to-tissue correlation. LA-ICP-MS and micro-XRF offer similar limits of detection for the elements Ca and P and thus, allow a cross-validation of the imaging results. LA-ICP-MS was particularly sensitive for determining Zn (LOD 20 μg g⁻¹, 15 μm spot size) in Daphnia magna, while the detection power of micro-XRF was insufficient in this context. However, LA-ICP-MS was inadequate for the measurement of the S distributions, which could be better visualized with micro-XRF (LOD 160 μg g⁻¹, 5 s live time). Both techniques are thus complementary in providing an exhaustive chemical profiling of tissue samples.     

Enhanced removal of bisphenol A by cyclodextrin in photocatalytic systems: Degradation intermediates and toxicity evaluation

At present, the assessment of photooxidation system mainly focuses on the photodegradation efficiency of target pollutant, lacking of the toxicity assessment in the photocatalysis process. Here, photodecomposition of bisphenol A (BPA) was used to investigate the performance of several cyclodextrin modified photocatalysts. Moreover, the comprehensive toxicity changes of BPA under different photocatalytic oxidation conditions were conducted. The β-cyclodextrin (β-CD) modified photocatalyst, including titanium dioxide (CM-β-CD-TiO₂), carbon nitride (CM-β-CD-C₃N₄) and cadmium sulfide (SH-β-CD-AM/CdS) exhibit high degradation rate and mineralization efficiency of BPA. The highest total organic carbon (TOC) removal of BPA observed in the oxidation system of SH-β-CD-AM/CdS nanoreactor (73.4%). The main oxidation intermediates in these systems were detected, and the comprehension toxicity of BPA and its oxidation intermediates in different system were compared by toxicity estimation software tool (T.E.S.T.) based on quantitative structure-activity relationship (QSAR) prediction. The results show that β-CD can facilitate the photodecomposition of the target contaminant. However, many oxidation intermediates with high comprehensive toxicity, even in the oxidation system with high BPA removal, can still be detected. Therefore, not only decomposition of target contaminant but also the comprehensive toxicity of oxidation intermediates should be regarded as index to evaluate a photocatalysis technology.     

Detoxifying CO2 Capture Reclaimer Waste by Anaerobic Digestion

The decrease in toxicity of carbon capture reclaimer monoethanolamine (MEA) waste (MEAw) during anaerobic degradation of such waste together with easily degradable organics was investigated. Samples were collected from a bioreactor at steady state with 86 % organic chemical oxygen demand removal at room temperature, which had been running on MEAw for 2 years. The toxicity of the digester effluents were 126, 42 and 10 times lower than that of the MEAw to the tested freshwater trophic groups of Pseudokirchneriella subcapitata, Daphnia magna and embryos of Danio rerio, respectively. The toxicity of the tested taxonomic groups after anaerobic digestion was mainly attributed to the ammonia generated by the degradation of MEAw.     

Toxicity of Zn-Fe Layered Double Hydroxide to Different Organisms in the Aquatic Environment

The application of layered double hydroxide (LDH) nanomaterials as catalysts has attracted great interest due to their unique structural features. It also triggered the need to study their fate and behavior in the aquatic environment. In the present study, Zn-Fe nanolayered double hydroxides (Zn-Fe LDHs) were synthesized using a co-precipitation method and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and nitrogen adsorption-desorption analyses. The toxicity of the home-made Zn-Fe LDHs catalyst was examined by employing a variety of aquatic organisms from different trophic levels, namely the marine photobacterium Vibrio fischeri, the freshwater microalga Pseudokirchneriella subcapitata, the freshwater crustacean Daphnia magna, and the duckweed Spirodela polyrhiza. From the experimental results, it was evident that the acute toxicity of the catalyst depended on the exposure time and type of selected test organism. Zn-Fe LDHs toxicity was also affected by its physical state in suspension, chemical composition, as well as interaction with the bioassay test medium.     

Joint QSAR analysis using the Free-Wilson approach and quantum chemical parameters

A new quantitative structure-activity relationship (QSAR) technique combining the Free-Wilson method and constructed quantum chemical parameters was used to simulate the aqueous solubility (Sw), 1-octanol/water partition coefficient (Kow) of 14 new synthesized benzanilide derivatives and their 96 h acute toxicity (EC50) to Daphnia magna. The mode of action of the 14 selected compounds to Daphnia magna was shown to be a complex process involving a physical partition stage and a bio-chemical reaction stage. The results also indicated that the joint (QSAR) analysis was much effective than the original Free-Wilson method and Hansch method not only in predicting properties/toxicity, but also in investigating the mode of action of chemicals.     

Separate detection of homologous surfactants by means of solid-contact unmodified and modified with molecular sieves potentiometric sensors

To improve the selectivity of surfactant sensors, the surface of their membranes was modified with molecular sieves with predetermined pore sizes. Water-soluble anionic, cationic and non-ionic surfactants were used as pore generators in the molecular sieves and introduced into the source membrane at the stage of its formation. The modified sensors enable detection of alkylsulfates homologues and alkylpyridinium with different lengths of the hydrocarbon chain (C₁₀-C₁₈); homologous poly(oxyethylated nonylphenols) differing in the number of oxyethyl groups (m = 10-100).A novel approach to separate detection of surfactant homologues implies the usage of inselective sensors as a multisensor system. The software-supported multisensor approach allows information of both mixture composition and concentrations of separate components in multicomponent systems to be obtained with a certain accuracy. Inselective non-modified sensors with the highest cross-sensitivity were used to design multisensor systems like an “electronic tongue”.The cross-sensitivity parameters of both source and modified sensors were estimated and the possibility of their usage in multisensor systems like an “electronic tongue” for analysis of multicomponent solutions of homologous surfactant is shown. Analytical signals were processed by artificial neural networks.     

Radiolysis of selected antibiotics and their toxic effects on various aquatic organisms

This study was conducted to investigate the decomposition of three γ-irradiated antibiotics (e.g., tetracycline, sulfamethazine, and lincomycin) and to compare the toxic effects on Daphnia magna, Vibrio fischeri, and Pseudokirchneriella subcapitata. The median cell growth inhibition concentrations (IC₅₀) of tetracycline, lincomycin, and sulfamethazine for P. subcapitata dramatically increased (e.g., toxicity decreased) after radiolysis. The results demonstrated that γ-radiation treatment was efficient to decompose antibiotics and thereby their toxicity on P. subcaptitata remarkably decreased due to reduced parent compounds.     

Joint QSAR Analysis Using the Free-Wilson Approach and Quantum Chemical Parameters

Abstract

A new quantitative structure-activity relationship (QSAR) technique combining the Free-Wilson method and constructed quantum chemical parameters was used to simulate the aqueous solubility (S _w), 1-octanol/water partition coefficient (K _ow) of 14 new synthesized benzanilide derivatives and their 96 h acute toxicity (EC₅₀) to Daphnia magna. The mode of action of the 14 selected compounds to Daphnia magna was shown to be a complex process involving a physical partition stage and a biochemical reaction stage. The results also indicated that the joint (QSAR) analysis was much effective than the original Free-Wilson method and Hansch method not only in predicting properties/toxicity, but also in investigating the mode of action of chemicals.