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Methodology for the electrochemical decomposition of bisphenol A is described. The electrochemical behaviour of bisphenol A at a Pt electrode was investigated by means of cyclic voltammetric techniques. The electrochemical oxidation of bisphenol A led to the deactivation of the electrode as a result of the deposition of an electropolymerized film. However the electrochemical decomposition of bisphenol A could be achieved by the use of a platinum coated titanium (Pt/Ti) electrode and a tin dioxide coated (SnO2/Ti) electrode. The electrolysis was carried out galvanostatically at a constant current of 0.3 A. The mineralization of bisphenol A was monitored by determining the amount of total organic carbon. Furthermore, the generation and nature of intermediates produced in the electrochemical reactions was investigated. Although large amounts of aliphatic acids were generated by electrolysis with the Pt/Ti anode, they were produced only to a small extent in at the SnO2/Ti anode. In the case of the SnO2/Ti anode, bisphenol A is rapidly oxidized to carbon dioxide and water, compared to the Pt/Ti anode. [ABSTRACT FROM AUTHOR]

A reflective surface plasmon resonance (SPR) sensor was evaluated for real-time monitoring of scale deposition. The sensor consists of an optical fiber, only 5 mm at the gold-coated tip of the sensing area. The effect of silica growth on the sensor response was evaluated using a Na 2 SiO 3 solution. The sensitivity of the sensor to silica was 1.6 ± 0.3 nm per one immersion in the solution of 1000 mg/L (as SiO 2 ) at 85 °C and subsequnt air drying, as indicated by the SPR peak shift. The amount of silica deposited on the gold surface was measured by the quartz crystal microbalance method, and the SPR sensitivity of 0.089 nm/ng to silica mass was obtained. The detection limit (3σ) of the SPR sensor was 17 ng, corresponding to a thickness of 2.5 nm for amorphous silica. The SPR sensor was tested in geothermal brine sampled at the Sumikawa Geothermal Power Plant, where a clear SPR shift was observed, suggesting the effectiveness of the SPR sensor for scale monitoring., (© 2024. The Author(s), under exclusive licence to The Japan Society for Analytical Chemistry.)

The design of a simple approach enabling the detection of bisphenol A (BPA) in water samples without the need for large amounts of solvents is of utmost importance. This paper reports a simple method for the separation, concentration, and quantification of BPA in water samples using high-performance liquid chromatography with fluorescence detection (HPLC-FLD) after its microextraction into an in situ formed organic ion-associate (IA) liquid phase (LP). Novel IA phase components without conjugated double bonds, such as benzene rings, were investigated. Ethylhexyloxypropylamine hydrochloride and sodium dodecyl sulfate solutions were added to the water samples to form IAs. The aqueous phase and ion-associate liquid phase (IALP) were separated by centrifugation. The aqueous phase was removed, and the liquid phase was recovered and measured using HPLC-FLD or HPLC-electrochemical detection (ECD). The concentrated phase (IALP) had a relatively low viscosity and could be injected directly into the chromatograph without dissolving it in organic solvents. The detection limits for BPA by HPLC-FLD and HPLC-ECD were 0.009 and 0.3 µg L -1 , respectively.

The aim of this study was to clarify the impact of differences between historical and recently introduced irrigation and drainage management systems on water quality in the rivers around paddy fields. We investigated the seasonal variation in nutrients concentration and dissolved organic carbon (DOC) components in single- (used for intake only) and dual-purpose (used for both intake and drainage) channels during a 4-year period in the Himi region of Toyama, Central Japan. The system of dual-purpose channel has traditionally been used in the region of this study. A total of 197 three-dimensional excitation-emission matrix (3DEEM) fluorescence spectra of DOM in waters were applied for the parallel factor analysis (PARAFAC) modeling. Based on the 3DEEM and PARAFAC, the abundance of terrestrial humic-like components in the dual-purpose channel was significantly higher than that in the single-purpose channel. The even long-chain n-fatty acids derived associated with rice cropping in sediments of the dual-purpose channels were 22-30-fold higher than that of the single-purpose channel. In addition, the turbidity values of the river waters had significantly positive linear correlations with concentrations of K + , DOC, and humic-like components. These observations indicate that the dissolved nutrient concentrations in the river water were higher in the dual-purpose channel compared to those of the single-purpose channel, which may be supplied by leaching from the inflow of soil particles from the paddy fields. During the mid-irrigation period, the quantity of epiphytic chlorophyll a on artificial substrate tiles in the dual-purpose channel were 3.1-4.1-fold higher than that in the single-purpose channel. This study clear that the input of paddy drainage during the irrigation season significantly changes the DOC components in river waters and irrigation management is strongly linked to the primary production in agricultural channels. Therefore, it is important to consider the impact of the introduction of different irrigation and drainage management systems on water quality and productivity in order to maintain the riverine ecosystems around rice paddies, which are based on historical water use systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

A highly sensitive and simple solid-phase colorimetry for Cr(VI) was proposed. It was based on the ion-pair solid-phase extraction of Cr-diphenylcarbazide (DPC) complex with sedimentable dispersed particulates. The concentration of Cr(VI) was measured from the color tones obtained by image analysis of the photo of sediment. Various conditions, e.g., material and amounts of adsorbent particulates, chemical properties and concentration of counter ions, and pH, were optimized for the formation and quantitative extraction of the complex. In the recommended procedure, 1 mL of sample was put into a 1.5 mL microtube where powder form adsorbent and reagents, i.e., XAD-7HP particles, DPC, sodium dodecyl sulfate, amido sulfuric acid, and sodium chloride had been packed. The analytical operation was completed within 5 min by gently shaking the microtube and allowing it to stand until enough amounts of particulates were deposited to take a picture. Chromium (VI) up to 2.0 ppm was determined, and the detection limit was 0.0034 ppm. The sensitivity was enough to determine Cr(VI) at lower concentrations than the water quality of standard (0.02 ppm). This method was successfully applied to the analysis of simulated industrial wastewater samples. The stoichiometry of the extracted chemical species was also investigated by applying the same equilibrium model as the ion-pair solvent extraction., (© 2023. The Author(s), under exclusive licence to The Japan Society for Analytical Chemistry.)

We present a lossy mode resonance (LMR) sensor fabricated by chemical bath deposition (CBD) using a U-shaped optical fiber with an exposed core. The ZnO particles that generate LMR were prepared by a very costly method in three steps via permanganate activation and the deposition of ZnO on the fiber core using CBD. The process of deposition was monitored in real time through the optical fiber, and a clear absorption spectrum with an LMR peak was obtained. The surface of the sensor with absorbance reaching 1.0 was covered with nano- to submicron particles of ZnO. The refractive index (RI) sensitivity of the sensor was measured using sucrose solution and was found to increase as the amounts of ZnO on the sensor increased, reaching 23 Abs/RI unit (RIU). The RI resolutions of the sensors with absorbance reaching 0.40, 0.65, and 1.0 during CBD were determined as ΔRI = 0.000060, 0.00017, and 0.00018, respectively, with a 99.7% confidence interval for the RI. Pretreatment during CBD was found to dramatically affect the fabrication of LMR sensors owing to their size and occupancy of deposited ZnO particles, the effects of which can be observed in real time using fiber optics., (© 2022. The Author(s), under exclusive licence to The Japan Society for Analytical Chemistry.)

Soil enzymes are biological indicators in environmental and agricultural monitoring. However, brownish humic acid (HA) in samples interferes significantly with various analytical methods, especially in optical-based techniques. Here, we implemented a coagulation-flocculation process to carry out continuously an enzymatic reaction without separation and transfer of a sample solution. The elimination of HA in a soil suspension using poly-γ-glutamic acid (PGA) by coagulation to minimize the HA interference in soil enzymatic analysis was investigated. As a result of the optimization of preliminary parameters, the removal efficiency of HA was > 92% in 100 mg L -1 HA in neutral pH, using 100 mg L -1 PGA and aluminum trivalent as a coagulant aid. However, the fluorescent intensity of the enzyme product (i.e., 4-methylumbelliferone) decreases by about 50% as HA was removed under the conditions used. A decrease in the enzymatic detection of 3,3',5,5'-tetramethylbenzidine (TMB) was not observed from treated samples even though the initial level of HA was different. The results suggested that the coagulation-flocculation approach is suitable for the reduction of HA interference, while maintaining target analyte detection. Therefore, the proposed sample treatment can be used to examine enzyme activity based on TMB product detection without regular standard addition calibration., (© 2022. The Author(s), under exclusive licence to The Japan Society for Analytical Chemistry.)

A novel simple and functional colorimetric methodology for on-site environmental water analysis was proposed. This method combines coloration of the analyte and extraction of the colored species on dispersed particulates during their sedimentation in the same container. The whole analysis can be performed within 15 min by comprising the addition of 1 mL of sample solution into a 1.5-mL microtube containing the powders of coloring reagents and the sedimentable fine particulates as an adsorbent. The analyte is determined by comparing the sediment color with the standard color by visual inspection or the color information of the photo image. The potential of this methodology was demonstrated through developing colorimetry for Fe 2+ with o-phenanthroline, NO 2 - by azo-dye formation, HCHO by the MBTH method, and PO 4 3- by the 4-aminoantipyrine method based on the enzyme reactions. The material, size, amount of the adsorbent particles, and other conditions were optimized for each analytes. The advantages of the methodology were as follows: high sensitivity, easy controllability of the sensitivity over the wide range by the amount, size, and material of the particulates, lower interference from the colored matrix components due to obtaining the color data from not the aqueous phase but the sedimented particulates, and acceleration of the color development rate by the particulates as seen in NO 2 - determination as consequence shorten the operation time. A simple device equipped with twin cells was proposed for on-site analysis which contains two successive different coloring operations. The developed methods were successfully applied to the environmental water samples with the good agreement of the results with those by the usual instrumental methods., (© 2022. Springer-Verlag GmbH Germany, part of Springer Nature.)

Fiber optic sensors for monitoring scale deposition in geothermal brine and hot spring water should be safe, easily fabricated, and readily disposable. These desired features already have been enhanced in plastic optical fibers (POFs) and U-shaped sensors for other applications. The present work reports a U-shaped POF sensor for CaCO 3 scale deposition. The sensors were easily fabricated by thermally bending the bulk POF without removing the cladding. At the bend, the percentage of total internal reflection between the water and the POF surface is affected by the high refractive index of the CaCO 3 deposit. The optical responses of the U-shaped sensor to CaCO 3 formation were investigated in a mixture of calcium chloride dehydrate and sodium hydrogen carbonate using a white-light source and a spectroscopic detector. The sensor was responsive to CaCO 3 formation on the sensor surface and was especially sensitive at small bending radii. The sensitivity was further enhanced by increasing the number of bends. Finally, the U-shaped POF sensor was applied to the monitoring of CaCO 3 scale deposition in hot spring water sampled at Matsushiro, Japan., (© 2022. The Author(s), under exclusive licence to The Japan Society for Analytical Chemistry.)

Formaldehyde (HCHO) is a naturally occurring compound found in ambient air which can induce cancer and sick-building syndrome. It plays an important role in the formation of OH radicals, which are connected to the formation of various airborne chemicals. Herein, we present a simple modeling for the simulation of diurnal variations in the HCHO concentration of ambient air. This was achieved using data collected during different seasons from November 2015 to March 2017 at a suburban location in Toyama City (Japan), where non-methane hydrocarbon (NMHC) levels were low at sub carbon ppm (ppmC) order. The modeling was based on the assumption that photochemical reactions of methane were the major factor of secondary HCHO formation. The model took into account the production and decomposition of HCHO by photochemical reactions as well as its loss due to other reactions such as dry deposition. Accordingly, the model's equation contained terms for solar radiation, temperature, and methane concentration. The results predicted using the model showed good agreement with the experimental data observed on fine days, i.e., except rainy, foggy, and heavily cloudy days. The relationships between HCHO concentration and solar radiation/temperature on different days as well as the seasonal variation of HCHO concentration were also interpreted by the proposed model. This study contributes to the evaluation of the pollution levels of formaldehyde. Moreover, the model may be used to demonstrate the impact of increasing methane levels, with regard to global warming and the background levels of HCHO in the atmosphere.

Dissolved humic substances (DHSs) are the major components of organic matter in the aquatic environment. DHSs are well known to considerably affect the speciation, solubility, and toxicity of a wide variety of pollutants in the aquatic environment. In this study, the effects of the toxicity of heavy metals and hydrophobic organic pollutants (HOPs) on Chlamydomonas reinhardtii in the presence of humic acid (HA) were examined by a microscale algal growth inhibition (μ-AGI) test based on spectrophotometric detection. To clarify the relationship between the chemical properties of HAs and the toxicity change of pollutants, eight HAs from different sources were prepared and used. HAs were responsible for mitigating the toxicity of Hg, Cu, pesticides (γ-HCH, 2,4-D, and DDT), and polycyclic aromatic hydrocarbons (PAHs) such as naphthalene (Nap), anthracene (Ant), and benzo[a]pyrene (BaP). In particular, an approximately 100-fold decrease in the toxicity of BaP was observed in the presence of 10 ppm HAs extracted from tropical peat. The results indicated that the carboxylic group content and the HA molecular weight are correlated to the changes in the heavy metal toxicity. For HOPs, the aromaticity and polarity of HAs are crucial for mitigating their toxicity. Furthermore, it was clearly shown that the lake water including a high concentration of DHSs collected from Central Kalimantan, Indonesia, reduced the toxicity of Hg and γ-HCH on Chlamydomonas reinhardtii. Graphical abstract.

We present an electrochemical long period fiber grating (LPFG) sensor for electroactive species with an optically transparent electrode. The sensor was fabricated by coating indium tin oxide onto the surface of LPFG using a polygonal barrel-sputtering method. LPFG was produced by an electric arc-induced technique. The sensing is based on change in the detection of electron density on the electrode surface during potential application and its reduction by electrochemical redox of analytes. Four typical electroactive species of methylene blue, hexaammineruthenium(III), ferrocyanide, and ferrocenedimethanol were used to investigate the sensor performance. The concentrations of analytes were determined by the modulation of the potential as the change in transmittance around the resonance band of LPFG. The sensitivity of the sensor, particularly to methylene blue, was high, and the sensor responded to a wide concentration range of 0.001 mM to 1 mM.

We designed an electrode that has the ability to sense a target cell. This new electrode is intended for use in cell recognition via electron-transfer and cross-linker peptide immobilization. Myelopeptide-4 (MP-4:FRPRIMTP) is a marrow-origin peptide that interacts with receptors of the human leukemia cell line (K562 cells), and allows their differentiation. The YYYYC electron-transfer peptide improves the electron-transfer accessibility from an electroactive compound to an electrode. Oligoalanine plays the role of a cross-linker that immobilizes a peptide series (Ac-FRPRIMTPYYYYCAAAAA) to collagen, which then allows it to be cast onto an electrode. Use of the electrode with a peptide increased the peak currents of [Fe(CN) 6 ] 4-/3- and also improved the reversibility of redox. These improvements are due to the interaction between [Fe(CN) 6 ] 4-/3- and the peptide. When electrochemical impedance spectroscopy (EIS) measurements were carried out using a collagen/peptide probe-immobilized electrode, the electron transfer resisitance was lower than that without the peptide. The detection of K562 cells was based on an increase in resistance, because MP-4 was bound to the receptors on the cell surface. The responses were linear and ranged in number from 27 to 2,000 cells/mLwith a detection limit of 8 cells/mL. Recoveries of 50 and 1,000 cells/mL in human serum were accomplished at rates of 98 and 101%, respectively. Consequently, the proposed procedure is a powerful new concept for cytosensing., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Herein, we propose an evanescent-wave fiber optic sensing technique for the anionic dye uranine based on ion association extraction. The sensor was prepared by removing a section of the cladding from a multimode fiber and hydrophobization of the exposed core surface. Uranine was extracted in association along with hexadecyltrimethylammonium (CTA) ion onto the fiber surface and detected via absorption of the evanescent wave generated on the surface of the exposed fiber core. The effect of CTA + concentration added for ion association was investigated, revealing that the absorbance of uranine increased with increasing CTA + concentration. A change in the sensor response as a function of the added uranine concentration was clearly observed. The extraction data were analyzed using a distribution equilibrium model and a Freundlich isotherm. The uranine concentration in the evanescent field of the fiber optic was up to 54 times higher than that in the bulk solution, and the limit of detection (3σ) for uranine was found to be 1.3 nM., Competing Interests: The authors declare no conflicts of interest.

We developed an ion-associate phase (IAP)-extraction/acid back-extraction system for the preconcentration and atomic spectrometric determination of lithium trace amounts in water. The chelating reagent for lithium also works as a constituent of the extraction phase. The lithium in a 10 mL sample solution was converted through a chelate complex reaction with 2,2,6,6-tetramethyl-3,5-heptanedione (HDPM). The addition of a benzyldimethyltetradecylammonium ion caused the formation of IAP suspension in the solution. Centrifugation of the solution led to the isolation of a liquid organic phase and the lithium complex was extracted as the upper phase from the centrifuge tube. After the aqueous phase was removed, lithium was back-extracted with a 400 μL nitric acid solution from the IAP. The acid phase was measured using liquid-electrode-plasma atomic-emission-spectrometry (LEP-AES) or graphite-furnace atomic-absorption spectroscopy (GF-AAS). The detection limits were 0.02 mg/L for LEP-AES and 0.02 μg/L for GF-AAS. This system was applied to the determination of environmental water. The HDPM in the organic phase was reusable.

Wildfires that expose the soil organic layer to high heat levels can alter soil organic matter (SOM), which includes water-soluble organic matter (WSOM) components. Various evaluation methods were used to characterize and quantify the effects of high heat levels on SOM and WSOM, including ion chromatography, thermogravimetry-differential thermal analysis (TG-DTA), colorimetry, elemental analysis, pyrolysis-gas chromatography-mass spectrometry using tetramethylammonium hydroxide (TMAH-py-GC/MS), total organic carbon (TOC) analysis, three-dimensional excitation-emission matrix (3DEEM) spectroscopy, and high-performance size-exclusion chromatography. In this study, we applied each of these evaluation methods using soil samples that were collected from broadleaf, coniferous, and bamboo forests and peatland in Japan and exposed to different initial high heat levels. Based on the TG-DTA results, the remaining mass in select soil samples markedly decreased when reheated to approximately 200°C. Comparatively, the TMAH-py-GC/MS results indicated a drastic change in SOM composition and the production of low molecular organic components (10 ) at this temperature. The TOC analysis results also indicated a significant increase in the proportion of WSOM. Colorimetry and elemental analysis results indicated that the soil color was dependent upon the initial heating temperature and was related to the H/C and O/C atomic ratios. The results of this study can form the basis for future similar studies for accurately characterizing and quantifying the heat effects on soil, and the effects of increasing wildfires due to climate change.

Treatment with an electromagnetic field, one of the potential techniques to inhibit scale deposition from water, has the advantage of not requiring the addition of any chemicals. Field tests using a fibre optic sensor were conducted to evaluate the effect that the treatment of hot spring water in Matsushiro, Japan with an electromagnetic field had on calcium carbonate scale formation. The optical response to scale deposition recorded by the fibre optic sensor decreased as a consequence of the application of an electromagnetic field, and the effectiveness of scale formation inhibition depended on the frequency of the electromagnetic field. This evidence was compared with results from changes in scale mass measured using the quartz crystal microbalance (QCM) method. Mass increases of the scale formed on the quartz crystal surface in hot spring water were inhibited by electromagnetic field treatment. These results were verified performing a column flow test, whereby the flow rate of hot spring water through a column was measured.

We used an electron-transfer carbohydrate-mimetic peptide (YYYYC) to construct an electrochemical cytosensing system. Magnetic beads were modified with either asialofetuin (ASF) or soybean agglutinin (SBA) to evaluate the effect on cell sensing. Because SBA binds to the galactose residue that exists at the terminals of the carbohydrate chains in ASF, the target protein was accumulated on the protein magnetic beads. SBA is an example of N-acetylgalactosamine- and galactose-binding proteins that readily combine with YYYYC. When the peptides and protein-immobilized beads competed for a target protein, the peak current of the peptides changed according to the concentration of the protein at the 10 -12  M level. Next, human myeloid leukemia cells (K562 cell) were measured using the peptide and the carbohydrate chains on the cell surface that recognize SBA. The electrode response was linear to the number of K562 cells and ranged from 1.0 × 10 2 to 5.0 × 10 3  cells mL -1 . In addition, detection of a human liver cancer cell (HepG2 cell) was carried out using interactions with the peptide, the ASF receptors in HepG2 cells, and the carbohydrate chains of ASF. The peak currents were proportional and ranged between 5.0 × 10 1 and 1.5 × 10 3  cells mL -1 . When the values estimated from an electrochemical process were compared with those obtained by ELISA, the results were within the acceptable range of measurement error., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Micro-organic ion-associate phase (IAP) extraction was combined with a micro-volume back-extraction (MVBE) to reduce coexisting components and viscosity in the concentrates. Heavy metals were converted into a complex with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol in a 40-mL sample solution, and were extracted into ion associates. After centrifugation and discarding the aqueous phase, trace metals were stripped from IAP into a nitric acid solution, followed by GF-AAS determination. Only one vessel was required for 400-fold enrichment. The detection limits (3σ b ) for Cd, Ni, and Pb were 0.6, 3.7, and 0.8 ng/L, respectively. This method was applied in recovery tests in seawater.

Increases in global wildfires and fire severity are expected to result from global warming. Severe wildfires not only burn surface vegetation but also affect forest soil. Humic substances play key roles in the transport of nutrients and the carbon cycle in terrestrial ecosystems. In this study, we evaluated the effects of forest fires on the chemical properties of fulvic acid (FA) and humic acid (HA) extracted from non-burned and burned forest soils in Gunma, Japan. The differential thermal analysis of FA indicated that the intensity of exothermic reaction peak at 400 °C was 2-fold higher than that from non-burned soil. Based on pyrolysis-gas chromatography-mass spectrometry analysis with tetramethyl ammonium hydroxide, the amount of pyrolysate compounds in FA from burnt soil was significantly lower than that in FA from non-burnt soil. Therefore, we can conclude that the forest fire caused the significant change in the properties of FA such as increasing the aromaticity and refractory. In addition, the concentration of dissolved organic carbon with low molecular weight in surface soil increased after forest fire. This study suggests that the denaturation of soil organic matter by wildfire can affect the carbon cycle in terrestrial ecosystems.

Tetrahalobisphenol A (TXPBAs, X = Br or Cl), TBBPA and TCBPA, which are widely used as flame retardants, ultimately disposed of in landfills. In landfills, enzymatically oxidized TXBPAs can be covalently incorporated into humic acids (HAs) to form coupling products (HA-TXBPAs). In the present study, HA-TXBPAs were prepared by catalytic oxidation with iron(III)-phthalocyanine-tetrasulfate as a model of oxidative enzymes. The stability of HA-TXBPAs was evaluated by incubating them under physicochemical conditions of landfills (pH 9 and 50 °C). For HA-TBBPA, 18-26% of TBBPA was released from HA-TBBPA, due to the acid dissociation of the loosely bound TBBPA. However, no additional release was observed, even after 30 days, indicating that 74-82% of the TBBPA was incorporated into the HA. For HA-TCBPA, 3-4% of TCBPA and a major byproduct, 4-(2-hydroxyisopropyl)-2,6-dichlorophenol, was found to be loosely incorporated into HA. For both TBBPA and TCBPA, covalently bound organo-halogens were not released during the 30 days of incubation. Inhibition of the growth of Chlamydomonas reinhardtii was indicated when trace levels of TXBPAs (approximately 0.1 μM) were present. These results suggest that HA-TXBPAs contain not only covalently incorporated TXBPAs but also loosely bound TXBPAs and halophenols. The latter in HA-TXBPAs have the potential to leach from landfills and affect aquatic ecosystems., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

For use in the voltammetric sensing of galactose-dependent proteins, we modified magnetic beads with a peptide that had both electroactive- and molecular recognition properties. The peptide consisted of a YXY sequence and behaved as an electron-transfer carbohydrate-mimetic peptide that would combine with proteins. With this tool, the protein could be detected via a label-free system. We synthesized several penta- and hexa-peptides with a cysteine residue on the C-terminals to examine the properties of peptides. These peptides contained amino acid residues (X) of alanine, serine, or tyrosine. The peptides were immobilized on magnetic beads via N-(8-maleimidocapryloxy) succinimide. Soybean agglutinin(SBA), the in vivo function of which has been well established in animals, was selected as a model protein. The protein was detected via the changes in electrode response due to the oxidation of tyrosine residues from the phenol group to quinone. As a result, SBA was selectively accumulated on the beads modified with YYYYC. The calibration curve of SBA was linear and ranged from 2.5 × 10 -12 to 1.0 × 10 -10  M. With this system, SBA was recovered in human serum at values that ranged from 98 to 103%. Furthermore, the beads with peptides were regenerated five times using a protein denaturant. Accordingly, this electrochemical system was simple and could be rapidly applied to the detection of galactose-recognition proteins., (Copyright © 2017 Elsevier B.V. All rights reserved.)

We present a spectroelectrochemical fiber-optic sensor with an optically transparent electrode. The sensor was fabricated by coating indium tin oxide (ITO) onto the surface of fiber-optic core chips using a polygonal barrel-sputtering method. The ITO-coated fiber-optic probe can be simply and cheaply mass-produced and used as a disposable probe. The sensing is based on changes in an attenuated total reflection signal accompanying the electrochemical oxidation-reduction of an analyte at the electrode. The properties of an ITO-coated fiber-optic probe as an optically transparent electrode were investigated for varying thicknesses of ITO. The sensor responses were successfully enhanced with an additional level of selectivity via an electrostatically adsorbed, self-assembled monolayer, which comprised a polyanion and polycation.

We developed an electrochemical microalgal bioassay for the determination of heavy metal toxicity in water on the basis of the alkaline phosphatase (ALP) enzyme inhibition of Chlamydomonas reinhardtii. Five heavy metals were chosen as toxicants: Hg, Cd, Pb, Zn, and Cu. The induced ALP activity of C. reinhardtii was inhibited using the phosphate starvation method, and the results were evaluated by measuring the electrochemical oxidation of p-aminophenol (PAP) following the enzymatic conversion of p-aminophenyl phosphate (PAPP) as a substrate. The rapid determination of enzymatic activity was achieved using hydrodynamic voltammetry in a 50 μL micro-droplet with a rotating disk electrode (RDE). Enzymatic activity over a PAPP substrate is affected by heavy metal ions, and this phenomenon decreases the chronoamperometric current signal. The concentrations of Hg, Cd, Pb, Zn, and Cu in which the ALP activity was half that of the control (EC 50 ) were found to be 0.017, 0.021, 0.27, 1.30, and 1.36 μM, respectively. The RDE system was demonstrated to be capable of detecting enzymatic activity by using a small amount of regent, a reaction time of only 60 s, and a detection limit of 5.4 × 10 -7 U., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

A carbohydrate/electro-transfer peptide probe was fabricated to perform cell sensing. The probe consisted of a cello-oligosaccharide that was created by the conjugation of an electron-transfer peptide (Y 5 C) and a carbohydrate via a Schiff base. An oxidation wave due to a phenolic hydroxyl group was obtained by scanning with a glassy carbon electrode. This cell-sensing system was based on a competitive reaction between carbohydrates on a cell surface and the probe as each reacted to a protein that recognized the carbohydrate. When amounts of the protein and probe were constant, the peak current of the probe was changed as the number of cells increased. A human histocytic lymphoma cell (U937 cell) with carbohydrates such as glucose and N-acetylglucosamine on its surface was selected as the target cell. Wheat germ agglutinin (WGA) binded to both the probe and the carbohydrates on U937 cells, which resulted in a linear peak current of the cellobiose/electron-transfer peptide at concentrations that ranged from 100 to 3500 cells/ml. The values of the cell sensing using this electrochemical method were consistent with those established via ELSIA. The sensitivity of this procedure, however, was two-fold superior to that of ELISA. Consequently, this carbohydrate/electron-transfer peptide could be a powerful tool for cell sensing and searching for carbohydrate chains on a cell surface., (Copyright © 2017 Elsevier B.V. All rights reserved.)

We present a novel fiber optic sensor for real-time sensing of silica scale formation in geothermal water. The sensor is fabricated by removing the cladding of a multimode fiber to expose the core to detect the scale-formation-induced refractive index change. A simple experimental setup was constructed to measure the transmittance response using white light as a source and a spectroscopy detector. A field test was performed on geothermal water containing 980 mg/L dissolved silica at 93 °C in Sumikawa Geothermal Power Plant, Japan. The transmittance response of the fiber sensor decreased due to the formation of silica scale on the fiber core from geothermal water. An application of this sensor in the evaluation of scale inhibitors was demonstrated. In geothermal water containing a pH modifier, the change of transmittance response decreased with pH decrease. The effectiveness of a polyelectrolyte inhibitor in prevention of silica scale formation was easily detectable using the fiber sensor in geothermal water.

Electrochemical sensing of ovalbumin (OVA) was performed using magnetic beads with OVA recognition (RNRCKGTDVQAW)/electron-transfer (YYYYC) peptides. The focus of this study was to construct a highly sensitive and regenerative tool for OVA detection based on the interaction between a protein and peptide-1(RNRCKGTDVQAWYYYYC). The peptide-1 was introduced to the bead through four types of cross-linking reagents. Magnetic beads of different sizes with N-(6-maleimidocaproyloxy)sulfosuccinimide (Sulfo-EMCS) were also prepared. An oxidation peak due to tyrosine residues at 0.65 V depended on the distance of the electron-transfer peptide from the bead surface and on the surface area of the magnetic beads that contacted the electrode surface. The response of the electro-transfer peptide moiety was decreased because the protein was accumulated via the recognition peptide on the beads. When using Sulfo-EMCS and beads that were 6.0-6.9 μm in diameter, the calibration curve of OVA was linear and ranged from 8.0 × 10 -13 to 2.0 × 10 -11  M. To regenerate the magnetic beads, the measurements were achieved after removal of the OVA using a denaturing reagent. When OVA was added to fetal bovine serum containing a complex matrix, OVA was recovered at a rate of 98-100%. Consequently, these magnetic beads could be a powerful tool for the sensing of OVA in real samples., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A fiber-optic sensor capable of real-time monitoring of biofilm formation in water was developed. The sensor can be easily fabricated by removing the cladding of a multimode fiber optic to expose the core. The sensing action is based on the penetration of an evanescent wave through a biofilm formed on the surface of the exposed fiber core during total internal reflection. The proposed setup can be used to analyze the transmittance response over a wide wavelength range using a white-light source and a spectroscopy detector. The change in transmittance with respect to the biofilm formation on the fiber core surface was observed. The findings from this study showed that the sensor detection had better sensitivity at near-infrared wavelengths than at visible-light wavelengths. Moreover, the sensitivity of this sensor could be controlled by surface modifications of the core surface through electrostatic interactions, involving a silane coupling layer, polyanions, and polycations. The developed sensor was successfully applied to evaluating of the effectiveness of a commercial biofilm inhibitor.

To electrochemically sense lymphoma cells (U937), we fabricated a multifunctional peptide probe that consists of cell-penetrating/apoptosis-inducing/electron-transfer peptides. Electron-transfer peptides derive from cysteine residue combined with the C-terminals of four tyrosine residues (Y4). A peptide whereby Y4C is bound to the C-terminals of protegrin 1 (RGGRLCYCRRRFCVCVGR-NH2) is known to be an apoptosis-inducing agent against U937 cells, and is referred to as a peptide-1 probe. An oxidation response of the peptide-1 probe has been observed due to a phenolic hydroxyl group, and this response is decreased by the uptake of the peptide probe into the cells. To improve the cell membrane permeability against U937 cells, the RGGR at the N-terminals of the peptide-1 probe was replaced by RRRR (peptide-2 probe). In contrast, RNRCKGTDVQAWY4C (peptide-3 probe), which recognizes ovalbumin, was constructed as a control. Compared with the other probes, the change in the peak current of the peptide-2 probe was the greatest at low concentrations and occurred in a short amount of time. Therefore, the cell membrane permeability of the peptide-2 probe was increased based on the arginine residues and the apoptosis-inducing peptides. The peak current was linear and ranged from 100 to 1000 cells/ml. The relative standard deviation of 600 cells/ml was 5.0% (n = 5). Furthermore, the membrane permeability of the peptide probes was confirmed using fluorescent dye., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A reaction to casein, along with β-lactoglobulin, is a main cause of milk allergies, and also is a useful indicator of protein in allergic analyses. In the present study, a simple casein sensor was developed based on the interaction between a phosphate group of casein and electroactive [Ru(NH3)6](3+). We evaluated the voltammetric behavior of a casein-[Ru(NH3)6](3+) complex using a glassy carbon electrode. When the ruthenium(III) complex was combined with the phosphate groups of casein, the structure of the casein was changed. Since the hydrophobicity of casein was increased due to the binding, the casein was adsorbed onto the electrode. Furthermore, we modified an electrode with a ruthenium(III) ions/collagen film. When the sensor was applied to the detection of the casein contained in milk, the values coincided with those indicated by the manufacturer. Accordingly, this electrode could be a powerful sensor for the determination of casein in several foods.

Daunomycin penetrates the membrane of a U937 cell, which is a human histiocyte-related lymphoma cell. Several arginine-rich peptides have also exhibited a high degree of permeability with these cells. Therefore, we attempted to improve the membrane permeability of daunomycin by coupling it with an arginine-rich peptide. The cell membrane permeability of daunomycin was monitored using voltammetry, because daunomycin is an electroactive compound. First, daunomycin was combined with N-(6-maleimidocaproyloxy)sulfosuccinimide. Second, the cross-linking agent with daunomycin was bound to the cysteine residue of RRRRRRRRGC (peptide-1). The two-step synthesis suppressed the formation of by-products that might have conjugated with the amino groups of peptide-1. After the quinone moieties of daunomycin were reduced using an electrode, an oxidation peak appeared due to the moieties. The peak current of daunomycin with U937 cells had decreased. For the mixture of the daunomycin/peptide-1 probe and cells, the electrode response was smaller than that of daunomycin with the cells. Thus, the membrane penetration of the daunomycin/peptide-1 probe was improved compared with the use of only daunomycin. In addition, the membrane penetration of the probe was measured using fluorescence spectroscopy. The sensitivity of the electrochemical procedure was 100-fold that was obtained by fluorescence spectrometry., (Copyright © 2015 Elsevier B.V. All rights reserved.)

We designed a new electroactive peptide probe that has a molecular recognition function for the sensing of a protein. Ovalbumin (OVA) was the model protein, and when RNRCKGTDVQAW interacted with OVA, it conjugated with a tyrosine-rich peptide (Y4C). This peptide is electroactive, has a high degree of biocompatibility, and offers the possibility of gene expression. To measure the effect of a number of the tyrosine residues, voltammetric measurements were conducted using a series of tyrosine-rich peptides (YnC, n = 3-7) with sensitivities that ranged from 10(-9) to 10(-8) M. The electrode response of Y5C was the maximum value in the series. However, the peak current did not increase when the number of tyrosine residues was increased in a linear fashion. This may have been due to the micelles that are formed by a tyrosine-rich surfactant peptide. Thus, Y4C was suitable as an electroactive label for the construction of the peptide probe. The electrode response of Y4CRNRCKGTDVQAW obtained by a glassy carbon electrode was 100-fold that of tyrosine alone. The measurement of OVA via the peptide probe resulted in a detection on the order of 10(-12) M. In contrast, the sensitivity of OVA using RCKGTDVQAWY4C probe was at the 10(-11) M level, because the hydrophobic moiety gave it a molecular recognition function. The recoveries of the OVA using Y4CRNRCKGTDVQAW in a solution containing fetal bovine serum ranged between 98 and 101%. Consequently, the combination of a specific peptide and an electroactive element could be a powerful probe for the sensing of proteins., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Soil enzymes play essential roles in catalyzing reactions necessary for nutrient cycling in the biosphere. They are also sensitive indicators of ecosystem stress, therefore their evaluation is very important in assessing soil health and quality. The standard soil enzyme assay method based on spectroscopic detection is a complicated operation that requires the removal of soil particles. The purpose of this study was to develop a new soil enzyme assay based on hydrodynamic electrochemical detection using a rotating disk electrode in a microliter droplet. The activities of enzymes were determined by measuring the electrochemical oxidation of p-aminophenol (PAP), following the enzymatic conversion of substrate-conjugated PAP. The calibration curves of β-galactosidase (β-gal), β-glucosidase (β-glu) and acid phosphatase (AcP) showed good linear correlation after being spiked in soils using chronoamperometry. We also performed electrochemical detection using real soils. Hydrodynamic chronoamperometry can be used to assess the AcP in soils, with a detection time of only 90 s. Linear sweep voltammetry was used to measure the amount of PAP released from β-gal and β-glu by enzymatic reaction after 60 min. For the assessment of soil enzymes, the results of hydrodynamic voltammetry assay compared favorably to those using a standard assay procedure, but this new procedure is more user-friendly, rapid and simple.

Herein, we present a novel spectroelectrochemical fiber-optic sensor that combines electrochemistry, spectroscopy, and electrostatic adsorption in three modes of selectivity. The proposed sensor is simple and consists of a gold mesh cover on a multimode fiber optic that uses attenuated total reflection as the optical detection mode. The sensing is based on changes in the attenuation of the light that passes through the fiber-optic core accompanying the electrochemical oxidation-reduction of an analyte at the electrode. Methylene blue and ferrocyanide were used as model analytes to evaluate the performance of the proposed sensor. The optical transmission changes generated by electrochemical manipulation showed a good linear relationship with the concentration and the limits of detection (3σ) for methylene blue and ferrocyanide at 2.0 × 10(-7) and 1.6 × 10(-3) M, respectively. The sensor responses were successfully enhanced with an additional level of selectivity via an electrostatically adsorbed, self-assembled monolayer (SAM), which consisted of a silane coupling layer, a polyanion, and a polycation. The improvement observed in the sensitivity of a SAM-modified fiber-optic sensor was rather encouraging. The optimized sensor had detection limits (3σ) of 8.3 × 10(-9) M for methylene blue and 7.1 × 10(-4) M for ferrocyanide. The developed sensor was successfully applied to the detection of ferrocyanide in simulated nuclear waste.

In this study, a peptide-1 (RNRCKGTDVQAW) constructing lysozyme was conjugated with an electroactive daunomycin in order to voltammetrically detect ovalbumin (OVA). Hetero-bifunctional cross-linking agents with four kinds of ethylene chains in differing lengths were used to bind the peptide-1 and daunomycin. After a cross-linking agent had reacted with an amino group of daunomycin, the compound was introduced into the peptide to the cysteine residue in the peptide using a pendant arm. The OVA was sensed via a change in the electrode response of the daunomycin moiety, based on the binding between the peptide and the OVA. The adsorption of the peptide probe on the electrode increased with increases in the ethylene chain. The binding constants between the peptide probes and the OVA, however, did not depend on the length of the chain. This was because the ethylene chain influenced the binding. When the peptide and the daunomycin were bound using N-(6-maleimidocaproyloxy) sulfosuccinimide, the electrode response of the peptide probe was the most sensitive from among the four cross-linking agents. The calibration curve of the OVA using the peptide probe was linear and ranged from 1.5×10(-11) to 3.0×10(-10)M. Furthermore, this method could be applied to the electrochemical sensing of the OVA in egg whites and in fetal bovine serum., (Copyright © 2014 Elsevier B.V. All rights reserved.)

When peat forest fires happen, it leads to burn soil and also humic acids as a dominant organic matter contained in peat soil as well as the forest. The structure and properties of humic acids vary depending on their origin and environment, therefore the transformation of humic acid is also diverse. The impacts of the peat fires on peat soil from Central Kalimantan, Indonesia were investigated through the characterization of humic acids, extracted from soil in burnt and unburnt sites. The characterization of humic acids was performed by elemental composition, functional groups, molecular weight by HPSEC, pyrolysate compounds by pyrolysis-GC/MS, fluorescence spectrum by 3DEEM spectrofluorometer, and thermogravimetry. The elemental composition of each humic substance indicated that the value of H/C and O/C of humic acids from burnt sites were lower than that from unburnt sites. The molecular weight of humic acids from burnt sites was also lower than that from unburnt sites. Pyrolysate compounds of humic acids from unburnt sites differed from those of humic acids from burnt soil. The heating experiment showed that burning process caused the significant change in the properties of humic acids such as increasing the aromaticity and decreasing the molecular weight.

This study proposes an optical fiber sensor for calcium carbonate (CaCO3) scale formation in water. The sensor is easily fabricated by removing the cladding of a multimode fiber to expose the core towards the surrounding medium in order to detect refractive index change. A variation of the transmittance response from the high refractive index of CaCO3 which precipitated on the fiber core surface was observed. The proposed setup can be used to analyze the transmittance response over wide range of wavelength using white light as a source and also a spectroscopy detector. The curve of the transmittance percentage over time showed that a fiber core with 200 μm has higher sensitivity as compared to a fiber core with 400 μm. The findings from this study showed that the sensor detection region at near infrared (NIR) wavelengths showed better sensitivity than visible light (VIS) wavelengths. Field tests were conducted using natural geothermal water at Matsushiro, Japan in order to verify the performance of the proposed sensor. The optical response was successfully evaluated and the analytical results confirmed the capability of monitoring scale formation in a geothermal water environment.

For this study, a new method was developed to electrochemically detect ovalbumin via its binding with the peptide-1(RNRCKGTDVQAW) in lysozymes. The peptide that exists at the C-terminal of a lysozyme was combined with ovalbumin. When an electroactive compound was introduced to the N-terminal side of the peptide through ethylene gycolbis(sulfosuccinimidyl succinate), the labeled peptide-1 served as a probe for the detection of ovalbumin. The electrode responses of labeled peptide-1 were measured after the labeled peptide-1 and ovalbumin were incubated in a 0.1 M phosphate buffer (pH 5.6). As a result, the electrode response decreased as the concentration of ovalbumin increased. The detection limit of ovalbumin was 2.3 × 10(-11) M as estimated at 3-fold the standard deviation (3σ) (n = 5). Because the steric structure of the peptide and some of the amino acid residues were related to the binding, we prepared a peptide-2, to which the N- and C-terminals of peptide-1 were alternated. The decrease in the response for the labeled peptide-2 was less than that for the labeled peptide-1. In addition, the peak current of a peptide-3, for which the D of peptide-1 was replaced with S, was hardly changed with or without ovalbumin. Therefore, it was clear that the binding was influenced by the steric factors and by the sequence of the peptide. However, a peptide-1 with bis(sulfosuccinimidyl) suberate was designed to investigate the hydrophobic influences on the probe. The change in the peak current was smaller than that of peptide-1 with ethylene gycolbis(sulfosuccinimidyl succinate), which was due to the hydrophobic properties of the alkyl chain between the peptide and the ovalbumin. The proposed method could be applied to the determination of ovalbumin in egg whites. Consequently, the concept becomes an electrochemical sensing method for proteins based on the protein-peptide interaction., (Copyright © 2014 Elsevier B.V. All rights reserved.)

To electrochemically detect concanavalin A (ConA), a new method was developed using mixed micelles between a non-ionic surfactant with a maltose moiety and electroactive daunomycin. The surfactants, in which the length of the alkyl chain was different, were n-decyl-β-D-maltoside, n-dodecyl-β-D-maltoside, and n-tetradecyl-β-D-maltoside. The measurement principle was due to the micelle breakdown caused by the binding between the ConA and maltose moieties. When ConA was combined with maltose moieties at a concentration of surfactant that was near the critical micelle concentration, the daunomycin that formed the micelles was moved to a solution from the micelles. As a result, the peak current of daunomycin increased as the concentration of ConA was increased. The mechanism was proposed using voltammetry, spectrometry, and gel filtration. The linear range using n-tetradecyl-β-D-maltoside was 2.0×10(-9) to 8.0×10(-8) M of ConA, and it was the most sensitive in the presence of the three surfactants. To examine whether selective binding took place, measurements with several proteins were carried out. The electrode responses of daunomycin were not influenced by the presence of 5.0×10(-6) M protein. Furthermore, this method could be applied to the determination of ConA in a serum, and to the measurement of sugar chains that can be combined with ConA on the cell surface., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Tetrabromobisphenol A (TBBPA), a type of brominated flame retardant that shows endocrine disruption effects, has been identified in leachates from landfills. Iron(III)-porphyrins that mimic the active site of peroxidases have been shown to be effective in oxidizing halogenated phenols, such as TBBPA. In the present study, TBBPA was subjected to oxidation with potassium monopersulfate (KHSO5) using an iron(III)-phthalocyanine-tetrasulfonic acid (FePcTS), structural analogue of iron(III)-porphyrin, in the presence of humic acid (HA), a major component in landfill leachates. When TBBPA was oxidized using the above system, the levels of degradation and debromination increased with increasing pH in the presence of HA. Because of landfill leachates are weakly alkaline (around pH 8), oxidation products derived from TBBPA were investigated at pH 8. Approximately 48% of the bromine in the degraded TBBPA was incorporated into HA, and hydroxy-tribromobisphenol A was determined to be the major brominated intermediate in the HA fraction. In the iron(III)-porphyrin catalytic systems, the brominated intermediate incorporated into HA is mainly TBBPA, and no hydroxy-substituted bromophenols are found. Thus, the catalytic power of FePcTS is higher than that of iron(III)-porphyrin catalysts.

A higher enrichment of organic pollutant, di(2-ethylhexyl) phthalate (DEHP) was found in estuary of Oyabe River and Jinzu River, Japan. Based on this, the distribution of DEHP between water and bed sediment was investigated as a model of organic pollutant through both the field investigation and laboratory experiment. The laboratory experiment was performed to examine the effect of seawater, organic matter in sediment and hydrophobicity (log K ow ) of organic pollutants. The result showed that salting-out effect due to the high salinity in seawater and organic matter in sediment contributed towards the increasing of DEHP distribution between water and sediment. Furthermore, the hydrophobicity of organic pollutant also enhances the distribution between water and sediment to a higher magnitude in the presence of seawater.

An improved molybdenum blue spectrophotometry using a soluble membrane filter and CaCO(3)-column was proposed for determining arsenic in drinking water supplied from ground water in the presence of phosphate. A 100 mL sample solution containing 0.5 - 10 μg arsenic was passed through a CaCO(3)-column to remove phosphate, arsenate (As(V)). Arsenite (As(III)) which was not retained on the column was oxidized to As(V). As(V) was converted into a heteropolymolybdenum blue anion. The blue anion was collected on a membrane filter as an ion-associate with n-dodecyltrimethylammonium ion by filtration. The filter was dissolved in 2 mL of 2-methoxyethanol. The absorbance of the solution was measured at 810 nm against a reagent blank. Total inorganic arsenic was determined by reducing As(V) to As(III) before the column treatment. The RSDs for 10 μg L(-1) of As(III) and As(V) were 2.9%. Phosphate 0.2 mg L(-1) (as P) and iron 0.1 mg L(-1) did not interfere with the determination of 10 μg L(-1) arsenic. The proposed method was successfully applied to ground waters.

The SOS/umu genotoxicity assay evaluates the primary DNA damage caused by chemicals from the β-galactosidase activity of S. typhimurium. One of the weaknesses of the common umu test system based on spectrophotometric detection is that it is unable to measure samples containing a high concentration of colored dissolved organic matters, sediment, and suspended solids. However, umu tests with electrochemical detection techniques prove to be a better strategy because it causes less interference, enables the analysis of turbid samples and allows detection even in small volumes without loss of sensitivity. Based on this understanding, we aim to develop a new umu test system with hydrodynamic chronoamperometry using a rotating disk electrode (RDE) in a microliter droplet. PAPG when used as a substrate is not electroactive at the potential at which PAP is oxidized to p-quinone imine (PQI), so the current response of chronoamperometry resulting from the oxidation of PAP to PQI is directly proportional to the enzymatic activity of S. typhimurium. This was achieved by performing genotoxicity tests for 2-(2-furyl)-3-(5-nitro-2-furyl)-acrylamide (AF-2) and 2-aminoanthracene (2-AA) as model genotoxic compounds. The results obtained in this study indicated that the signal detection in the genotoxicity assay based on hydrodynamic voltammetry was less influenced by the presence of colored components and sediment particles in the samples when compared to the usual colorimetric signal detection. The influence caused by the presence of humic acids (HAs) and artificial sediment on the genotoxic property of selected model compounds such as 4-nitroquinoline-N-oxide (4-NQO), 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), 1,8-dinitropyrene (1,8-DNP) and 1-nitropyrene (1-NP) were also investigated. The results showed that the genotoxicity of 1-NP and MX changed in the presence of 10 mg∙L-1 HAs. The genotoxicity of tested chemicals with a high hydrophobicity such as 1,8-DNP and 1-NP were decreased substantially with the presence of 1 g∙L-1 sediment. This was not observed in the case of genotoxins with a low log K(ow) value.