Simazine Research Articles

Revisiting the persulfate activation performance of seaweed derivied biochars: The composition and origin of pollutant degradation activity

A steady increase in seaweed production necessitates effective strategies to manage its post-production waste and its assosicated CO2 emission. Biochar formation stand out as a promising option, offering significant advantage for persulfate-activated water remediation processes. Herein, we investigated and compared the performance of two seaweed-derived biochars, focusing on their physical characteristics, heteroatoms, and chemical composition in activating persulfate (PS). Although, both seaweeds (Capsosiphon fulvescens (CF) and Undaria pinnatifida (SW)) that studied are edible, they exhibit unique catalytic behavior in the degradation of simazine (SMZ). The differences in simazine degradation activity observed in these biochars were primarily attributed to the description of metal active sites rather than the complex composition and specific surface area of the biochars. The identification of these active sites was achieved through various physical characterization tools (XRD, XPS, BET) and by examining the adsorption models and degradation patterns of simazine under different conditions. Our results demonstrate that the biochar derived from CF (100% removal) seaweed having metal active centres is more catalytic than SW (58.4% removal) derived biochar. ROS quantification and electrochemical studies suggest that simazine degradation occurs through different mechanisms in these biochars. Therefore, the CF-derived biochar catalytic system was optimized for simazine oxidation, with studies focusing on its degradation pathway, intermediate toxicity, and catalytic stability. This comprehensive study outlines the significance of selection of seaweed biomass for optimal activity in the persulfate-based oxidative system.

Enhanced simazine degradation via peroxymonosulfate activation using hemin-doped rice husk biochar as a novel Fe/N–C catalyst

The presence of herbicides, including simazine (SIM), in aquatic environments pose significant threats to these ecosystems, necessitating a method for their removal. In this study, a hemin-doped rice husk-derived biochar (RBC@Hemin20%) was synthesized using a simple, one-step pyrolysis, and its degradation efficiency towards SIM via peroxymonosulfate (PMS) was assessed. Under optimized conditions (hemin loading = 20 wt%, SIM = 0.5 ppm, RBC@Hemin20% catalyst = 0.2 g L−1, PMS = 2.0 mM, and pH = 5.84 [unadjusted]), RBC@Hemin20%, as an Fe/N–C catalyst, could activate PMS to achieve >99% degradation of SIM. Based on radical scavenger and electron spin resonance spectroscopy (ESR) experiments, both radical (•OH and SO4•−) and non-radical (such as singlet oxygen, 1O2) mechanisms and electron transfer were involved in the degradation system. Significant mineralization (97.3%) and reusability efficiency (∼74.1% SIM degradation after 4 applications) were exhibited by the RBC@Hemin20%/PMS system, which also maintained a remarkable degradation efficiency in tap-, river-, and ground-water. Additionally, the RBC@Hemin20%/PMS system exhibited rapid degradation of tetracycline (TC) and diclofenac (DCF), indicating its prospects in the degradation of other organic pollutants of aquatic environments. The plausible degradation mechanism pathways of SIM are proposed based on identified intermediates. Finally, the toxicity of these intermediate products is analysed using the Ecological Structure Activity Relationship (ECOSAR) software. It is expected that this study will expand the current knowledge on the synthesis of efficient biomass-based Fe/N–C composites for the removal of organic pollutants in water.

Multiple barriers as an efficient treatment for removing pesticides aiming direct potable reuse: A pilot scale study

Water reuse for potable purposes can represent a realistic source supply of drinking water in areas with water scarcity. Therefore, combining conventional wastewater treatment technologies with advanced technologies is necessary to remove contaminants and obtain high-quality and safe water. In this study, the pesticides and degradation products, atrazine (ATZ), hydroxyatrazine (ATZOH), deethylatrazine (DEA), deisopropylatrazine (DIA), simazine (SMZ), ametryn (AMT), diuron (DIU), 2,4-D, fipronil (FIP), fipronil sulfide (FIP-SF) and fipronil sulfone (FIP-SN) were evaluated in effluent after membrane bioreactor (MBR), effluent after advanced treatment by multiple barriers (MBR, reverse osmosis, UV/H2O2 and activated carbon), in tap water collected in the urban region of Campinas and in the Atibaia River (water supply source from city of Campinas). The pesticide concentrations in the Atibaia River and the post-MBR effluent ranged between 1 and 434 ng L−1 and 1 and 470 ng L−1, respectively. Therefore, the Atibaia River and the post-MBR effluent had the same magnitude pesticide concentrations. In the production of potable water reuse, after the multiple barriers processes, only fipronil (1 ng L−1) and atrazine (3 ng L−1) were quantified in some of the samples. In tap water from Campinas, atrazine, ATZOH, DEA, diuron, and 2,4-D were quantified in concentrations ranging between 3 and 425 ng L−1. Therefore, when comparing drinking water obtained from conventional treatment with potable water reuse, according to the pesticides studied, it is possible to conclude that the advanced treatment used on a pilot scale is promising for use in a potable water reuse plant. However, studies involving more microbiological and chemical parameters should be conducted to classify potable water reuse as drinking water.

Assessing the negative impact of chlorantraniliprole, isoxaflutole, and simazine pesticides on phospholipid membrane models and tilapia gill tissues

The indiscriminate and, very often, incorrect use of pesticides in Brazil, as well as in other countries, results in severe levels of environmental pollution and intoxication of human life. Herein, we studied plasma membrane models (monolayer and bilayer) of the phospholipid Dioleoyl-sn-glycerol-3-phosphocholine (DOPC) using Langmuir films, and large (LUVs) and giant (GUVs) unilamellar vesicles, to determine the effect of the pesticides chlorantraniliprole (CLTP), isoxaflutole (ISF), and simazine (SMZ), used in sugarcane. CLTP affects the lipid organization of the bioinspired models of DOPC π-A isotherms, while ISF and SMZ pesticides significantly affect the LUVs and GUVs. Furthermore, the in vivo study of the gill tissue in fish in the presence of pesticides (2.0 × 10−10 mol/L for CLTP, 8.3 × 10−9 mol/L for ISF, and SMZ at 9.9 × 10−9 mol/L) was performed using optical and fluorescence images. This investigation was motivated by the gill lipid membranes, which are vital for regulating transporter activity through transmembrane proteins, crucial for maintaining ionic balance in fish gills. In this way, the presence of phospholipids in gills offers a model for understanding their effects on fish health. Histological results show that exposure to CLTP, ISF, and SMZ may interfere with vital gill functions, leading to respiratory disorders and osmoregulation dysfunction. The results indicate that exposure to pesticides caused severe morphological alterations in fish, which could be correlated with their impact on the bioinspired membrane models. Moreover, the effect does not depend on the exposure period (24h and 96h), showing that animals exposed to pesticides for a short period suffer irreparable damage to gill tissue. In summary, we can conclude that the harm caused by pesticides, both in membrane models and in fish gills, occurs due to contamination of the aquatic system with pesticides. Therefore, water quality is vital for the preservation of ecosystems.

Green analytical method based on salt assisted graphene oxide dispersive solid phase extraction of symmetrical triazine herbicides in environmental water samples for liquid chromatographic determination

ABSTRACT Graphene oxide (GO) was used as sorbent in dispersive solid phase extraction (DSPE) to enrich and extract some triazine herbicides from environmental water samples. It can form dispersed colloids in aqueous phase and provides rich functional groups for the formation of hydrogen bonding or π–π electrostatic interaction with benzene ring organic compounds containing oxygen and nitrogen functional groups. GO was synthesised by modified Hummers method and characterised with Fourier transform infrared (FT-IR) spectroscopy. As complete collection of GO after adsorption process is difficult task, in this established salt-assisted (SA)-GO-DSPE method, it was found to be aggregated and centrifuged in the presence of NaCl. The optimum value for main parameters that influenced extraction efficiency were investigated. Under the optimised conditions, low limits of detection (LODs) (0.12–0.80 ng mL −1), limits of quantification (LOQ) (0.4–2.68 ng mL −1), and good extraction recoveries (69.06–95.53%) were obtained for simultaneous extraction of simazine (SIZ), atrazine (ATZ), propazine (PRZ)) and prometryn (PRN). The relative standard deviations (RSD) of intraday (n = 6) and interday (n = 9) precisions were 2.54 to 5.84% and 4.38 to 8.56%, respectively. At the end, the applicability of the method was evaluated and target analytes were not detected in real samples. The proposed method is environment friendly and promising for trace analysis of pesticides including the target herbicides in environmental water samples.

Bioinformatics analysis of the potential mechanisms of Alzheimer’s disease induced by exposure to combined triazine herbicides

Background The development of Alzheimer’s disease (AD) is promoted by a combination of genetic and environmental factors. Notably, combined exposure to triazine herbicides atrazine (ATR), simazine (SIM), and propazine (PRO) may promote the development of AD, but the mechanism is unknown. Aim To study the molecular mechanism of AD induced by triazine herbicides. Methods Differentially expressed genes (DEGs) of AD patients and controls were identified. The intersectional targets of ATR, SIM, and PRO for possible associations with AD were screened through network pharmacology and used for gene ontology (GO) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) enrichment analysis. The binding potentials between the core targets and herbicides were validated by molecular docking and molecular dynamics. Results A total of 1,062 DEGs were screened between the AD patients and controls, which identified 148 intersectional targets of herbicides causing AD that were screened by network pharmacology analysis. GO and KEGG enrichment analysis revealed that cell cycling and cellular senescence were important signalling pathways. Finally, the core targets EGFR, FN1, and TYMS were screened and validated by molecular docking and molecular dynamics. Conclusion Our results suggest that combined exposure to triazine herbicides might promote the development of AD, thereby providing new insights for the prevention of AD.

Pesticides removal from water using activated carbons and carbon nanotubes

ABSTRACT The conventional water treatment technique (CT) widely applied cannot alone remove pesticides efficiently from water. Therefore, this work aimed to provide technical and scientific support for the association of pulverized activated carbon (PACs), granular activated carbon (GACs), and carbon nanotubes (CNT) with CT concerning atrazine (ATZ), simazine (SMZ), and diuron (DIU) removal. Actual conditions of pre/during, and post-treatment points of application, within water production process line, in water treatment plants (WTPs), using the pesticides in two forms, commercial product (CP) and analytical standard (SD). It was possible to demonstrate significant differences regarding the removal of ATZ, SMZ, and DIU in their SD and CP forms for the PACs, GACs, and CNTs. The minimum dosage of CNT required for adequate adsorption of all pesticides was superior to 160 mg. L−1; is 400% higher than the minimum dosage of 40 mg. L−1 is required for PAC application. ATZ, SMZ, and DIU in the SD form were more efficiently removed with percentages superior to 96.4% for ATZ, 98.2% for SMZ, and 99.1% for DIU. The characteristics of the adsorptive materials did not guide the adsorption efficacy. Instead, chemical interaction, contact time, and point application were critical factors. The pre-treatment and post-treatment applications were the most efficient, with removals oscillating from 97.7% to 100% for ATZ, 97.7% to 100% for SMZ, and 99.1 to 100% for DIU PAC and GAC, respectively. Highlights The pesticides forms of application, SD and CP, affect adsorption efficiency. Adsorbent point of application, in WTPLS, and contact time are key factors for pesticide removal. The primary adsorption mechanism in all the materials tested was chemical. The pre-treatment and post-treatment were the most efficient PACs and GACs application forms, respectively.

Assessing the role of polyethylene microplastics as a vector for organic pollutants in soil: Ecotoxicological and molecular approaches

Microplastics (MPs), pharmaceuticals and pesticides are emerging pollutants with proposed negative impacts on the environment. Rising interest in investigations of MPs is likely related to their potential to accumulate in agricultural systems as the base of the food chain. We applied an integrated approach using classic bioassays and molecular methods to evaluate the impact associated with a mixture of three types of polyethylene (PE) microbeads, namely, white (W), blue (B), and fluorescent blue (FB), and their interactions with pollutants (OCs), including ibuprofen (IB), sertraline (STR), amoxicillin (AMX) and simazine (SZ), on different soil organisms. PE-MPs exhibited different abilities for the adsorption of each OC; W selectively adsorbed higher amounts of SZ, whereas B and FB preferably retained AMX.Standard soil was artificially contaminated with OCs and MPs (alone or combined with OCs) and incubated for 30 days. The presence of MPs or MPs and OCs (MIX) in soil did not produce any effect on Caenorhabditis elegans endpoint growth, reproduction, or survival. Inhibition of leaf growth in Zea mays was detected, but this negative effect declined over time, while the inhibition of root growth increased, especially when OCs (32%) or MIX (47%) were added. Moreover, the expression of the antioxidant genes CAT 1, SOD-1A and GST 1 on plants was affected by the treatments studied. The addition of MPs or MIX significantly affected the soil bacterial phylogenetic profile, which selectively enriched members of the bacterial community (particularly Proteobacteria). The predicted functional profiles of MP/MIX samples indicated a potential impact on the carbon and nitrogen cycle within the soil environment. Our results indicate that MPs and their capability to act as pollutant carriers affect soil biota; further studies should be carried out on the bioavailability of OCs adsorbed by microplastics and how long it takes to leach these OCs into different organisms and/or ecosystems.

Degradation of simazine by heat-activated peroxydisulfate process: A coherent study on kinetics, radicals and models

Recently, studies on the degradation of emerging pollutants by activated persulfate (PS) have been widely reported. As a classic process, heat-activated peroxydisulfate (PDS) has been extensively used in practical engineering. However, the establishment of the quantitative relationship between the reduction of pollutants and PDS and the kinetic model of the heat-activated PDS process are rarely reported. In this study, triazine herbicide simazine (SMZ), which is frequently found in the environment, was selected as the target pollutant, and a series of coherent studies including kinetics calculation, radicals identification, and product analysis provided the basis for the establishment of the model. The steady-state model and unsteady-state model initially described the process of heat-activated PDS and degradation effect on SMZ. It was found that in the process of heat/PDS, the degradation of SMZ was significantly related to the decomposition of PDS. The decomposition of each unit of PDS at the beginning of the reaction could lead to the degradation of 1.616 units of SMZ. In addition, during the reaction, sulfate radical (SO4•−) was the dominant radical and could be partly transformed to hydroxyl radical (•OH) to participate in the reaction (with the ratio of 25:1). Finally, it was noted that the reaction intermediates could not be ignored in the establishment of the unsteady-state model. This study provides a set of coherent research methods, which is conducive to further simulation of the heat-activated PDS process.

The effect of hybrid zinc oxide/graphene oxide (ZnO/GO) nano-catalysts on the photocatalytic degradation of simazine

The photocatalytic degradation of simazine (SIM) was investigated using zinc oxide/graphene oxide (ZnO/GO) composite materials under visible light irradiation. The reaction kinetics was studied to optimize the reaction parameters for efficient degradation of SIM. Batch studies were performed to investigate the effects of initial reaction pH, the loading of the ZnO onto GO, and mass of catalyst on the removal of SIM from aqueous solution. A pH of 2 was determined to be the optimal reaction pH for the different ZnO-loaded GO catalysts. In addition, a mass of 40 mg of catalyst in the reaction was observed to be the most effective for the catalysts synthesized using 20 and 30 mmol of Zn2+ ions; whereas a mass of 10 mg was most effective for the ZnO/GO composite material synthesized using 10 mmol Zn2+ ions. The reaction was observed to follow a second-order kinetics for the degradation process. Furthermore, the synthesized ZnO/GO composite catalysts resulted in higher reaction rates than those observed for pure ZnO. The 30 mmol ZnO/GO composite expressed a rate of SIM degradation ten times greater than the rate observed for pure ZnO, and sixty-two times greater than the rate of photolysis. In addition, the catalyst cycling exhibited a constant photocatalytic activity for the ZnO/GO composite over three reaction cycles without the need of a conditioning cycle.

Degradation of Atrazine, Simazine and Ametryn in an arable soil using thermal-activated persulfate oxidation process: Optimization, kinetics, and degradation pathway

This study examined the feasibility of applying thermal-activated persulfate (PS) oxidation for remediation of soil co-contaminated with s-triazine herbicides including Atrazine (ATZ), Simazine (SIM) and Ametryn (AME). Homogeneous activation using heating method (50 °C) was selected. Results showed that thermal-activated PS oxidation process may successfully degrade ATZ in soil and degradation efficiency was increased along the arising activation temperature. Higher PS dosages and depressed initial pH were beneficial for degradation while increasing initial ATZ concentration may hamper the degradation. The oxidation process may lead to changes of surface functional groups on soil. The presence of Cl−, HCO3− and H2PO4− at both of low and high concentrations may inhibit the degradation of ATZ. Soil depths may apparently influence the ATZ degradation which followed 0−10 < 10−30 < 30−60 cm mainly depending on the soil organic matter (SOM) contents. Thermal-activated PS may effectively degrade ATZ, SIM and AME under co-contaminated condition and the more favorable of ethyl group towards SO4− than isopropyl and methylation groups was detected. Both of SO4− and HO were identified to be responsible for degradation. Finally, degradation intermediates of ATZ, SIM and AME were identified by LC-Q-TOF-MS and detailed transformation pathways for three pesticides were proposed, respectively.

Maternal and Fetal Blood Pharmacokinetics and Organ Distribution of Atrazine, Propazine, Simazine, and Their Metabolites in Pregnant Rats After Chronic Oral Administration.

Environmental contamination by chlorotriazines has been evidenced in mother-child cohort suggesting more detailed risk assessment of these compounds in drinking water. Exposure of rodents to atrazine (ATZ) has been associated with alterations of endocrine and reproductive functions by disrupting neuroendocrine control at hypothalamus level. Perinatal exposure to low doses of ATZ has been associated with reproductive dysfunction, and to behavioral abnormalities in adult exposed during embryogenesis. The objectives of the current investigation were to (1) evaluate the influence of physicochemical properties of chlorotriazines on tissue distribution in pregnant rats and in fetuses and (2) gain a better understanding of fetal distribution of chlorotriazines in specific tissues, particularly in brain. Serial blood samples were obtained from pregnant rats after administration of ATZ, propazine (PRO), and simazine (SIM) via oral route at a dose of 10 mg/kg from day 15 to day 19. Maternal and fetal tissues were harvested at day 20, 24 h after the last dosing. The metabolic extraction ratio was estimated to 87% suggesting a significant first-pass effect explaining the low oral bioavailability. Blood exposure to parent compounds (ATZ, PRO, and SIM) was negligible (lower than 5%) compared with metabolite exposure. The main metabolite exposure involved diamino-s-chlorotriazine, ranging from 60% to 90% depending on the molecules administered. A correlation between tissue-to-blood ratio and physicochemical descriptors was observed for fat and mammary gland tissues but not for brain in adult rats. A more pronounced distribution in fetal brain was observed for ATZ and PRO, the 2 most lipophilic compounds.

Eliminación/Degradación de Triazinas Mediante Biorreactor de Membrana con Post-Tratamiento de Ozonización

The aim of the research was to evaluate the removal of micropollutants in a combined system MBR + ozonation. The research was carried out in a MBR scale laboratory plant which was fed with synthetic wastewater, doped with simazine (SIM), atrazine (ATZ) and terbutilazine (TBZ). The MBR operational conditions were: hydraulic retention time (HRT) of 20 h, organic loading rate (OLR) of 0.23 KgCOD/KgSSV·day, sludge retention time (SRT) of 30 d, and flux of 5.5 LMH. Two ozone doses were tested: low dose (16 mg O3/L) and high dose (45 mg O3/L). The removal eficiency of organic matter was 96%. For the studied triazines, low biodegradation effiencies were reached by biological treatment (MBR): 57%, 53% and 63% for SIM, ATZ and TBZ, respectively. The complementary treatment of ozonation improved the quality of the effluents. At low ozonation dose the overall removal efficiencies increased to 95%, 92% and 96% for SIM, ATZ and TBZ, respectively. At high ozonization dose the overall removal efficiencies were 98%, 97% and 97 % for SIM, ATZ and TBZ, respectively, percentages slightly higher than those obtained at low dose. The results showed the combination of MBR + O3 is effective to remove micropollutants from wastewater, contributing to the preservation of a good ecological state of water bodies.Keywords: Bioreactor, Membrane, Ozone, Triazines, Herbicides.

Occurrence, distribution, and fate of pesticides in an intensive farming region in the Brazilian semi-arid tropics (Jaguaribe River, Ceará)

This study is the first to assess herbicide levels in sediment of the Jaguaribe River, which is located in one of the largest agricultural areas of the tropical Brazilian semi-arid region (Ceara state), with the goal of evaluating the occurrence of herbicides as well as their geographical distribution pattern and environmental fate in this river. Sediment collection was performed in October 2012, and nine points were selected located along the river to its mouth, and the levels of atrazine (ATR), alachlor (ALA), bromacil (BRO), ethalfluralin (ETHA), fluridone (FLU), metolachlor (METO), norflurazon (NOR), simazine (SIM), tebuthiuron (TEB), and trifluralin (TRI) were determined. Sediment from each site was characterized by granulometric analysis and total organic carbon (TOC), humic acid (HA), and fulvic acid (FA) contents. ALA, BRO, ETHA, FLU, NOR (a prohibited compound), and TEB were detected in all samples analyzed, whereas herbicides ATR, METO, SIM, and TRI were not detected at any of the sampling sites. The total herbicide concentrations (∑herb) (the sum of six herbicides detected) per sampling sites ranged from 174.86 to 348.84 ng g−1 (fluvial zone) and 111.43 to 419.35 ng g−1 (estuary zone). The results showed that the sum of ETHA concentrations at all sampling points (ΣETHA) (1687.47 ng g−1) was the most abundant herbicide, followed by ΣBRO (201.43 ng g−1), ΣALA (41.73 ng g−1), ΣTEB (24.41 ng g−1), ΣFLU (1.33 ng g−1), and ΣNOR (0.43 ng g−1). The physicochemical properties of ATR, METO, and SIM favor their dispersion in the aqueous fraction; thus, the lack of these herbicides in the sediments is due to environmental partitioning. The environmental and geographical distribution pattern indicates that the estuarine zone is a sink that controls the fate of TEB, ALA, and FLU herbicides. Differently from expected results, data based on non-linear Spearman’s coefficient show that herbicides with high log K ow and K oc values were more likely to be found in the sediment inorganic fraction, whereas herbicides with high solubility and low K oc values were dispersed between both the organic and inorganic fractions of sediments.

Development of surface plasmon resonance sensors based on molecularly imprinted nanofilms for sensitive and selective detection of pesticides

Pesticides have been utilized in agriculture for decades. However, their widespread use has increased multiple concerns due to their known and suspected toxicities on long-term human health risks in scientific and industrial communities. Thus, detecting pesticides will have a great impact on their management, as well as improve their toxicity effects over humans. Here, we fabricate molecularly imprinted nanofilms and integrate them with surface plasmon resonance (SPR) sensors for sensitive, selective, fast and real-time detection of multiple pesticides, including cyanazine (SNZ), simazine (SMZ) and atrazine (ATZ). The molecularly imprinted nanofilms onto the SPR gold surfaces are prepared via UV polymerization reactions, which consist of N-methacryloyl-l-phenylalanine methyl ester (MAPA) as a functional monomer, 1-vinylimidazole (VIM) as a co-monomer, and ethylene glycol dimethacrylate (EGDMA) as a cross-linker. The real-time measurements on SPR sensor provide a detection range from 0.10 to 6.64nM, as well as denote a limit of detection (LOD) values of 0.095, 0.031 and 0.091nM for SNZ, SMZ and ATZ, respectively. Furthermore, we perform selectivity test, where SNZ, SMZ and ATZ are examined as competitor agents. Overall, the pesticide imprinted SPR sensors have been found to be highly selective and sensitive. These SPR sensors also hold great potential to be used an alternative method for the existing pesticide monitoring approaches due to their reusability, fast response, and easy-to-use properties, as well as can be tailored to detect and real-time monitor of other pesticides.

Electrochemical sensor based on molecularly imprinted composite membrane of poly(o-aminothiophenol) with gold nanoparticles for sensitive determination of herbicide simazine in environmental samples

A novel electrochemical sensor based on molecularly imprinted polymer membranes (MIPM) as biomimetic molecular recognition element involved in o-aminothiophenol functionalized Au nanoparticles (ATP@AuNPs) modified gold electrode was constructed for sensitive and selective detection of herbicide simazine (SMZ). The nano-scaled MIPM, with high specific surface area, was prepared by self-assembly of o-aminothiophenol (ATP) and electrodeposition of ATP@AuNPs in the presence of template SMZ. Cathodic current of SMZ was measured by cyclic voltammetry and the results exhibited that the proposed sensor possess a high electrocatalytic activity at a negative potential and a fast rebinding dynamics towards the reduction of SMZ in 0.01M H2SO4 solution (pH 1.7). Linear dependency of peak current on SMZ concentrations was observed from 0.03 to 140μM and detection limit was estimated to be 0.013μM (3S/N). The enhancement of sensitivity was attributed to the presence of gold nanoparticles (AuNPs) which decreased the electron-transfer impedance and increased imprinting sites, lead to the superior enrichment effect of the trace amount of SMZ in aqueous solvent. The developed SMZ imprinted sensor exhibited excellent long-term stability and acceptable repeatability. In addition, the proposed method was successfully applied to measure SMZ in several real samples with the spiked recoveries changing from 91.4% to 96.8%, showing a promising potential in practical application.

Sensitive analysis of simazine based on platinum nanoparticles on polyoxometalate/multi-walled carbon nanotubes

In this report, a novel molecular imprinted voltammetric sensor based on glassy carbon electrode (GCE) modified with platinum nanoparticles (PtNPs) involved in a polyoxometalate (H3PW12O40, POM) functionalized multi-walled carbon nanotubes (MWCNs) sheets was prepared for the determination of simazine (SIM). The developed surfaces were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) method. SIM imprinted GCE was prepared via electropolymerization process of 100mM pyrrole as monomer in the presence of 0.1M acetate buffer (pH 4.0) containing 25mM SIM. The linearity range and the detection limit of the developed method were calculated as 1.0×10−10–5.0×10−9M and 2.0×10−11M, respectively. In addition, the voltammetric sensor was applied to wastewater samples. The stability and reproducibility of the voltammetric sensor were also reported.

Phytoremediation of the organic Xenobiotic simazine by p450-1a2 transgenic Arabidopsis thaliana plants

ABSTRACTThe potential use of human P450-transgenic plants for phytoremediation of pesticide contaminated soils was tested in laboratory and greenhouse experiments. The transgenic P450 CYP1A2 gene Arabidopsis thaliana plants metabolize number of herbicides, insecticides and industrial chemicals. The P450 isozymes CYP1A2 expressed in A. thaliana were examined regarding the herbicide simazine (SIM). Transgenic A. thaliana plants expressing CYP1A2 gene showed significant resistance to SIM supplemented either in plant growth medium or sprayed on foliar parts. The results showed that SIM produces harmful effect on both rosette diameter and primary root length of the wild type (WT) plants. In transgenic A. thaliana lines, the rosette diameter and primary root length were not affected by SIM concentrations used in this experiment. The results indicate that CYP1A2 can be used as a selectable marker for plant transformation, allowing efficient selection of transgenic lines in growth medium and/or in soil-grown plants. The transgenic A. thaliana plants exhibited a healthy growth using doses of up to 250 μmol SIM treatments, while the non-transgenic A. thaliana plants were severely damaged with doses above 50 μmol SIM treatments. The transgenic A. thaliana plants can be used as phytoremediator of environmental SIM contaminants.

Evaluation of Monolithic and Core-Shell Columns for Separation of Triazine Herbicides by Reversed Phase High Performance Liquid Chromatography

Monolithic and core-shell columns were comparatively evaluated for separation of deisopropylatrazine (DIA), deethylatrazine (DEA), hydroxyatrazine (HAT), simazine (SIM) and atrazine (ATR) under similar conditions of elution, flow rate and sample volume. Although both columns provided separation of the analytes with resolution > 1.5, the core-shell column exhibited better efficiency, leading to narrower peaks. It has height equivalent to the theoretical plates (HETP) for DEA, DIA and HAT, eluted under isocratic elution, about 2.5 times smaller than those of the monolithic column. A soil sample was studied by ultrasound assisted extraction with 80:20 (v/v) acetonitrile:water, revealing the presence of HAT and ATR. This sample was enriched with 0.25, 0.50 and 1.0 mg kg-1 of the five triazine compounds and analyzed, leading to recovery percentages between 45 and 86%.

Evaluation of sequential injection chromatography for reversed phase separation of triazine herbicides exploiting monolithic and core–shell columns

This paper describes the development of reversed phase sequential injection chromatography (SIC) methods for separation of simazine (SIM) and atrazine (AT), as well as their metabolites deethylatrazine (DEA), deisopropylatrazine (DIA) and hydroxyatrazine (HAT) exploiting silica based monolithic (50×4.6mm) and core–shell (30×4.6mm, 2.7µm particles) columns. The separation was made by stepwise elution with two mobile phases: MP1 composed of 15:85 (v/v) acetonitrile: 2.5mmolL−1 acetic acid/ammonium acetate buffer (pH 4.2), and MP2, composed of 35:65 (v/v) acetonitrile: 2.5mmolL−1 acetic acid/ammonium acetate buffer (pH 4.2).The less hydrophobic compounds (DIA, HAT and DEA) eluted with MP1, whereas SIM and AT eluted with MP2. The method using core–shell column exhibited better chromatographic efficiency compared with monolithic column for separation of SIM and AT, but failed to provide base line separation of DIA and HAT. The proposed composition of mobile phases enabled the monolithic column to separate all the studied compounds with resolution >2.3 at flow rate of 35µLs−1 and sampling throughput of 8 analyses per hour, whereas in the core–shell the maximum flow rate allowed in the SIC system was 8µLs−1 (sampling throughput of 3 analyses per hour). The limits of detection were between 24µgL−1 (AT) and 40µgL−1 (DEA) using the monolithic column, and between 20µgL−1 (SIM) and 38µgL−1 (DEA) with the core–shell. Ultrasound-assisted extraction (80:20v/v acetonitrile:water) of a soil sample enriched with the five triazines (250, 500 and 1000µgkg−1) resulted recoveries between 51% and 121% of the spiked concentrations.