The Experts below are selected from a list of 1422 Experts worldwide ranked by ideXlab platform
Tebello Nyokong - One of the best experts on this subject based on the ideXlab platform.
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Electrocatalytic oxidation of Amitrole and diuron on iron(II) tetraaminophthalocyanine-single walled carbon nanotube dendrimer
Electrochimica Acta, 2010Co-Authors: Tawanda Mugadza, Tebello NyokongAbstract:Abstract FeTAPc-single walled carbon nanotube (SWCNT) dendrimers are employed as glassy carbon electrode modifiers for the electrocatalytic oxidations of Amitrole and diuron. The catalytic rate constants were 4.55 × 10 3 M −1 s −1 and 1.79 × 10 4 M −1 s −1 for Amitrole and diuron, respectively using chronoamperometric studies. The diffusion constants were found to be 1.52 × 10 −4 cm 2 s −1 and 1.91 × 10 −4 cm 2 s −1 for diuron and Amitrole, respectively. The linear concentration range for both were from 5.0 × 10 −5 to 1.0 × 10 −4 M and sensitivities of 0.6603 μA/μM and 0.6641 μA/μM for Amitrole and diuron, with corresponding limits of detection of 2.15 × 10 −7 and 2.6 × 10 −7 M using the 3 δ notation, respectively.
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Electrocatalytic Detection of Amitrole on the Multi-Walled Carbon Nanotube – Iron (II) tetra-aminophthalocyanine Platform
Sensors (Basel Switzerland), 2008Co-Authors: Msimelelo P. Siswana, Kenneth I. Ozoemena, Tebello NyokongAbstract:It is shown that iron(II) tetra-aminophthalocyanine complex electropolymerized onto a multi-walled carbon nanotube-modified basal plane pyrolytic graphite electrode greatly enhanced the electrocatalytic detetion of Amitrole (a toxic herbicide), resulting in a very low detection limit (0.5 nM) and excellent sensitivity of 8.80±0.44 μA/nM, compared to any known work reported so far. The electrocatalytic detection of Amitrole at this electrode occurred at less positive potential (~0.3 V vs Ag|ACl) and also revealed a typical coupled chemical reaction. The mechanism for this response is proposed. The electrode gave satisfactory selectivity to Amitrole in the presence of other potential interfering pesticides in aqueous solutions.
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electrocatalytic detection of Amitrole on the multi walled carbon nanotube iron ii tetra aminophthalocyanine platform
Sensors, 2008Co-Authors: Msimelelo Siswana, Kenneth I. Ozoemena, Tebello NyokongAbstract:It is shown that iron(II) tetra-aminophthalocyanine complex electropolymerized onto a multi-walled carbon nanotube-modified basal plane pyrolytic graphite electrode greatly enhanced the electrocatalytic detetion of Amitrole (a toxic herbicide), resulting in a very low detection limit (0.5 nM) and excellent sensitivity of 8.80±0.44 μA/nM, compared to any known work reported so far. The electrocatalytic detection of Amitrole at this electrode occurred at less positive potential (~0.3 V vs Ag|ACl) and also revealed a typical coupled chemical reaction. The mechanism for this response is proposed. The electrode gave satisfactory selectivity to Amitrole in the presence of other potential interfering pesticides in aqueous solutions.
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Electrocatalytic Detection of Amitrole on the Multi-Walled Carbon Nanotube – Iron (II) tetra-aminophthalocyanine Platform
MDPI AG, 2008Co-Authors: Tebello Nyokong, Kenneth I. Ozoemena, Msimelelo SiswanaAbstract:It is shown that iron(II) tetra-aminophthalocyanine complex electropolymerized onto a multi-walled carbon nanotube-modified basal plane pyrolytic graphite electrode greatly enhanced the electrocatalytic detetion of Amitrole (a toxic herbicide), resulting in a very low detection limit (0.5 nM) and excellent sensitivity of 8.80±0.44 μA/nM, compared to any known work reported so far. The electrocatalytic detection of Amitrole at this electrode occurred at less positive potential (~0.3 V vs Ag|ACl) and also revealed a typical coupled chemical reaction. The mechanism for this response is proposed. The electrode gave satisfactory selectivity to Amitrole in the presence of other potential interfering pesticides in aqueous solutions
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Electrocatalytic behaviour of carbon paste electrode modified with iron(II) phthalocyanine (FePc) nanoparticles towards the detection of Amitrole
Talanta, 2006Co-Authors: Msimelelo P. Siswana, Kenneth I. Ozoemena, Tebello NyokongAbstract:Abstract This paper describes the construction of a carbon paste electrode (CPE) impregnated with nanoparticles of iron(II) phthalocyanine (nanoFePc). The new electrode (nanoFePc-CPE) revealed interesting electrocatalytic behaviour towards Amitrole; pure catalytic diffusion-controlled process, with high Tafel slope (235 mV/decade) suggesting strong binding of Amitrole with nanoFePc catalyst. The effects of catalyst loading, varying pH and electrolytes were studied. The mechanism for the interaction of Amitrole with the nanoFePc is proposed to involve the Fe (III) Pc/Fe (II) Pc redox process. Using chronoamperometry ( E = +0.42 V versus Ag/AgCl) technique, the sensor was reliably employed for Amitrole assay at pH 12.0 phosphate buffer (with sodium sulphate as the supporting electrolyte) for up to 12 nM Amitrole with excellent sensitivity (ca. 3.44 μA/nM) and low detection limit (3.62 ± 0.11 nM, i.e. 0.305 μg L −1 using the Y B + 3 σB criterion and 0.85 ± 0.03 nM, i.e. 70 ng/L with the Y B + 2 σB criterion) as well as satisfactory amperometric selectivity coefficient ( K amp ≈ 7.4 × 10 −4 for ammonium thiocyanate, a component of many Amitrole herbicides, and 3.2 × 10 −3 for asulam pesticide). The surface of the electrode can easily be regenerated by simple polishing on an alumina paper, obtaining a fresh surface ready for use in a new assay. The proposed electrode was successfully applied in the quantification of Amitrole in its commercial formulation as well as in tap water samples.
Manuel Chicharro - One of the best experts on this subject based on the ideXlab platform.
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adsorptive stripping voltammetric determination of Amitrole at a multi wall carbon nanotubes paste electdrode
Electroanalysis, 2005Co-Authors: Manuel Chicharro, Esperanza Bermejo, Mónica Moreno, Alberto Sanchez, A. Zapardiel, Gustavo A. RivasAbstract:This work reports the excellent electrocatalytic activity of carbon nanotubes paste electrodes (CNTPE) prepared by dispersion of multi-wall carbon nanotubes (MWNT) within mineral oil toward the oxidation of 3-amino-1H-1,2,4triazole (Amitrole). The quantification is performed by adsorptive stripping voltammetry (AdSV). The influence of the paste composition and surface pretreatments as well as the Amitrole accumulation conditions on the adsorption and further electrooxidation of this herbicide is described. After potentiodynamic pretreatment in 0.050 M phosphate buffer pH 7.4 the Amitrole oxidation signal shifts 250 mV toward more negative potential and the sensitivity increases 29 fold, demonstrating that pretreated CNTPEs are extremely useful for a highly sensitive determination of Amitrole down to the sub-mM levels. The oxidation peak current is proportional to the Amitrole concentration over the range from 0.8 to 7.0 mM (5 min accumulation), with a detection limit of 0.6 mM (48 mgL � 1 ) and a precision of 4.3%, n ¼ 20. The proposed method was used for the determination of Amitrole in spiked river water (Alberche River (Madrid, Spain)) and tap water samples (Madrid, Spain) at levels higher than 0.6 mM.
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Adsorptive Stripping Voltammetric Determination of Amitrole at a Multi‐Wall Carbon Nanotubes Paste Electdrode
Electroanalysis, 2005Co-Authors: Manuel Chicharro, Esperanza Bermejo, Mónica Moreno, Alberto Sanchez, A. Zapardiel, Gustavo A. RivasAbstract:This work reports the excellent electrocatalytic activity of carbon nanotubes paste electrodes (CNTPE) prepared by dispersion of multi-wall carbon nanotubes (MWNT) within mineral oil toward the oxidation of 3-amino-1H-1,2,4triazole (Amitrole). The quantification is performed by adsorptive stripping voltammetry (AdSV). The influence of the paste composition and surface pretreatments as well as the Amitrole accumulation conditions on the adsorption and further electrooxidation of this herbicide is described. After potentiodynamic pretreatment in 0.050 M phosphate buffer pH 7.4 the Amitrole oxidation signal shifts 250 mV toward more negative potential and the sensitivity increases 29 fold, demonstrating that pretreated CNTPEs are extremely useful for a highly sensitive determination of Amitrole down to the sub-mM levels. The oxidation peak current is proportional to the Amitrole concentration over the range from 0.8 to 7.0 mM (5 min accumulation), with a detection limit of 0.6 mM (48 mgL � 1 ) and a precision of 4.3%, n ¼ 20. The proposed method was used for the determination of Amitrole in spiked river water (Alberche River (Madrid, Spain)) and tap water samples (Madrid, Spain) at levels higher than 0.6 mM.
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Determination of 3-amino-1,2,4-triazole (Amitrole) in environmental waters by capillary electrophoresis.
Talanta, 2003Co-Authors: Manuel Chicharro, Esperanza Bermejo, Antonio Zapardiel, Mónica MorenoAbstract:Abstract 3-Amino-1,2,4-triazole (Amitrole) is a widely used pesticide, with many difficulties to be analyzed at the regulatory level in drinking water, because its high solubility in water. This paper describes a simple and fast method for the simultaneous determination of Amitrole and atrazin-2-hydroxy, principal degradation product of s -triazines, by capillary zone electrophoresis. Separation and determination of these herbicides in water samples was performed in 0.02 mol l −1 phosphate buffer at pH 3.2. The method allows determination of the Amitrole and atrazin-2-hydroxy in water samples in concentration lower than 100 μg l −1 . The detection limits using a previous preconcentration step of Amitrole in Alberche River (Comunidad Autonoma de Madrid, Spain) and drinking water spiked samples was of 4 μg l −1 .
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Electrocatalytic amperometric determination of Amitrole using a cobalt-phthalocyanine-modified carbon paste electrode.
Analytical and bioanalytical chemistry, 2002Co-Authors: Manuel Chicharro, Esperanza Bermejo, Mónica Moreno, Antonio Zapardiel, Elena MadridAbstract:Cobalt-phthalocyanine-modified carbon paste electrodes are shown to be excellent indicators for electrocatalytic amperometric measurements of triazolic herbicides such as Amitrole, at low oxidation potentials (+0.40 V). The detection and determination of Amitrole in flow injection analysis with a modified carbon paste electrode with Co-phthalocyanine is described. The concentrations of Amitrole in 0.1 M NaOH solutions were determined using the electrocatalytic oxidation signal corresponding to the Co(II)/Co(III) redox process. A detection limit of 0.04 microg mL(-1) (4 ng Amitrole) was obtained for a sample loop of 100 microL at a fixed potential of +0.55 V (vs. Ag/AgCl) in 0.1 M NaOH and a flow rate of 4.0 mL min(-1). Furthermore, the modified carbon paste electrodes offers reproducible responses in such a system, and the relative standard deviation was 3.3% using the same surface, 5.1% using different surface, and 6.9% using different pastes. The performance of the cobalt-phthalocyanine-modified carbon paste electrodes is illustrated here for the determination of Amitrole in commercial formulations. The response of the electrodes is stable, with more than 80% of the initial retained activity after 50 min of continuous use.
Mónica Moreno - One of the best experts on this subject based on the ideXlab platform.
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adsorptive stripping voltammetric determination of Amitrole at a multi wall carbon nanotubes paste electdrode
Electroanalysis, 2005Co-Authors: Manuel Chicharro, Esperanza Bermejo, Mónica Moreno, Alberto Sanchez, A. Zapardiel, Gustavo A. RivasAbstract:This work reports the excellent electrocatalytic activity of carbon nanotubes paste electrodes (CNTPE) prepared by dispersion of multi-wall carbon nanotubes (MWNT) within mineral oil toward the oxidation of 3-amino-1H-1,2,4triazole (Amitrole). The quantification is performed by adsorptive stripping voltammetry (AdSV). The influence of the paste composition and surface pretreatments as well as the Amitrole accumulation conditions on the adsorption and further electrooxidation of this herbicide is described. After potentiodynamic pretreatment in 0.050 M phosphate buffer pH 7.4 the Amitrole oxidation signal shifts 250 mV toward more negative potential and the sensitivity increases 29 fold, demonstrating that pretreated CNTPEs are extremely useful for a highly sensitive determination of Amitrole down to the sub-mM levels. The oxidation peak current is proportional to the Amitrole concentration over the range from 0.8 to 7.0 mM (5 min accumulation), with a detection limit of 0.6 mM (48 mgL � 1 ) and a precision of 4.3%, n ¼ 20. The proposed method was used for the determination of Amitrole in spiked river water (Alberche River (Madrid, Spain)) and tap water samples (Madrid, Spain) at levels higher than 0.6 mM.
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Adsorptive Stripping Voltammetric Determination of Amitrole at a Multi‐Wall Carbon Nanotubes Paste Electdrode
Electroanalysis, 2005Co-Authors: Manuel Chicharro, Esperanza Bermejo, Mónica Moreno, Alberto Sanchez, A. Zapardiel, Gustavo A. RivasAbstract:This work reports the excellent electrocatalytic activity of carbon nanotubes paste electrodes (CNTPE) prepared by dispersion of multi-wall carbon nanotubes (MWNT) within mineral oil toward the oxidation of 3-amino-1H-1,2,4triazole (Amitrole). The quantification is performed by adsorptive stripping voltammetry (AdSV). The influence of the paste composition and surface pretreatments as well as the Amitrole accumulation conditions on the adsorption and further electrooxidation of this herbicide is described. After potentiodynamic pretreatment in 0.050 M phosphate buffer pH 7.4 the Amitrole oxidation signal shifts 250 mV toward more negative potential and the sensitivity increases 29 fold, demonstrating that pretreated CNTPEs are extremely useful for a highly sensitive determination of Amitrole down to the sub-mM levels. The oxidation peak current is proportional to the Amitrole concentration over the range from 0.8 to 7.0 mM (5 min accumulation), with a detection limit of 0.6 mM (48 mgL � 1 ) and a precision of 4.3%, n ¼ 20. The proposed method was used for the determination of Amitrole in spiked river water (Alberche River (Madrid, Spain)) and tap water samples (Madrid, Spain) at levels higher than 0.6 mM.
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Determination of 3-amino-1,2,4-triazole (Amitrole) in environmental waters by capillary electrophoresis.
Talanta, 2003Co-Authors: Manuel Chicharro, Esperanza Bermejo, Antonio Zapardiel, Mónica MorenoAbstract:Abstract 3-Amino-1,2,4-triazole (Amitrole) is a widely used pesticide, with many difficulties to be analyzed at the regulatory level in drinking water, because its high solubility in water. This paper describes a simple and fast method for the simultaneous determination of Amitrole and atrazin-2-hydroxy, principal degradation product of s -triazines, by capillary zone electrophoresis. Separation and determination of these herbicides in water samples was performed in 0.02 mol l −1 phosphate buffer at pH 3.2. The method allows determination of the Amitrole and atrazin-2-hydroxy in water samples in concentration lower than 100 μg l −1 . The detection limits using a previous preconcentration step of Amitrole in Alberche River (Comunidad Autonoma de Madrid, Spain) and drinking water spiked samples was of 4 μg l −1 .
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Electrocatalytic amperometric determination of Amitrole using a cobalt-phthalocyanine-modified carbon paste electrode.
Analytical and bioanalytical chemistry, 2002Co-Authors: Manuel Chicharro, Esperanza Bermejo, Mónica Moreno, Antonio Zapardiel, Elena MadridAbstract:Cobalt-phthalocyanine-modified carbon paste electrodes are shown to be excellent indicators for electrocatalytic amperometric measurements of triazolic herbicides such as Amitrole, at low oxidation potentials (+0.40 V). The detection and determination of Amitrole in flow injection analysis with a modified carbon paste electrode with Co-phthalocyanine is described. The concentrations of Amitrole in 0.1 M NaOH solutions were determined using the electrocatalytic oxidation signal corresponding to the Co(II)/Co(III) redox process. A detection limit of 0.04 microg mL(-1) (4 ng Amitrole) was obtained for a sample loop of 100 microL at a fixed potential of +0.55 V (vs. Ag/AgCl) in 0.1 M NaOH and a flow rate of 4.0 mL min(-1). Furthermore, the modified carbon paste electrodes offers reproducible responses in such a system, and the relative standard deviation was 3.3% using the same surface, 5.1% using different surface, and 6.9% using different pastes. The performance of the cobalt-phthalocyanine-modified carbon paste electrodes is illustrated here for the determination of Amitrole in commercial formulations. The response of the electrodes is stable, with more than 80% of the initial retained activity after 50 min of continuous use.
Gustavo A. Rivas - One of the best experts on this subject based on the ideXlab platform.
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adsorptive stripping voltammetric determination of Amitrole at a multi wall carbon nanotubes paste electdrode
Electroanalysis, 2005Co-Authors: Manuel Chicharro, Esperanza Bermejo, Mónica Moreno, Alberto Sanchez, A. Zapardiel, Gustavo A. RivasAbstract:This work reports the excellent electrocatalytic activity of carbon nanotubes paste electrodes (CNTPE) prepared by dispersion of multi-wall carbon nanotubes (MWNT) within mineral oil toward the oxidation of 3-amino-1H-1,2,4triazole (Amitrole). The quantification is performed by adsorptive stripping voltammetry (AdSV). The influence of the paste composition and surface pretreatments as well as the Amitrole accumulation conditions on the adsorption and further electrooxidation of this herbicide is described. After potentiodynamic pretreatment in 0.050 M phosphate buffer pH 7.4 the Amitrole oxidation signal shifts 250 mV toward more negative potential and the sensitivity increases 29 fold, demonstrating that pretreated CNTPEs are extremely useful for a highly sensitive determination of Amitrole down to the sub-mM levels. The oxidation peak current is proportional to the Amitrole concentration over the range from 0.8 to 7.0 mM (5 min accumulation), with a detection limit of 0.6 mM (48 mgL � 1 ) and a precision of 4.3%, n ¼ 20. The proposed method was used for the determination of Amitrole in spiked river water (Alberche River (Madrid, Spain)) and tap water samples (Madrid, Spain) at levels higher than 0.6 mM.
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Adsorptive Stripping Voltammetric Determination of Amitrole at a Multi‐Wall Carbon Nanotubes Paste Electdrode
Electroanalysis, 2005Co-Authors: Manuel Chicharro, Esperanza Bermejo, Mónica Moreno, Alberto Sanchez, A. Zapardiel, Gustavo A. RivasAbstract:This work reports the excellent electrocatalytic activity of carbon nanotubes paste electrodes (CNTPE) prepared by dispersion of multi-wall carbon nanotubes (MWNT) within mineral oil toward the oxidation of 3-amino-1H-1,2,4triazole (Amitrole). The quantification is performed by adsorptive stripping voltammetry (AdSV). The influence of the paste composition and surface pretreatments as well as the Amitrole accumulation conditions on the adsorption and further electrooxidation of this herbicide is described. After potentiodynamic pretreatment in 0.050 M phosphate buffer pH 7.4 the Amitrole oxidation signal shifts 250 mV toward more negative potential and the sensitivity increases 29 fold, demonstrating that pretreated CNTPEs are extremely useful for a highly sensitive determination of Amitrole down to the sub-mM levels. The oxidation peak current is proportional to the Amitrole concentration over the range from 0.8 to 7.0 mM (5 min accumulation), with a detection limit of 0.6 mM (48 mgL � 1 ) and a precision of 4.3%, n ¼ 20. The proposed method was used for the determination of Amitrole in spiked river water (Alberche River (Madrid, Spain)) and tap water samples (Madrid, Spain) at levels higher than 0.6 mM.
Shi Yanqin - One of the best experts on this subject based on the ideXlab platform.
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Stability, antibacterial ability, and inhibition of “zinc burning” of Amitrole as thermal stabilizer for transparent poly(vinyl chloride)
Journal of Thermal Analysis and Calorimetry, 2018Co-Authors: Wang Yating, Ma Meng, Shi YanqinAbstract:Amitrole is reported as a novel kind of transparent poly(vinyl chloride) (PVC) thermal stabilizer that has both excellent inhibition of “zinc burning” thermal stability and antibacterial ability in this paper, which provide the possibility of applying the whole PVC industry into medical and food packaging, artificial leather, wire and cable, indoor decoration, and so on. From the results of Congo red test, discoloration test, and dynamic thermal stability test, we could clearly find out that Amitrole could effectively replace the unstable chlorine atom and inhibit “zinc burning” of transparent PVC, while the long-term stability should be improved. Next, the stabilization mechanism of Amitrole was also confirmed. The antibacterial activity of Amitrole was measured by the bacteriostatic ring experiments. It was observed that the PVC films had good antibacterial properties after modified by Amitrole. At last, optimal design of the Amitrole/ZnSt2 (1:1)/ESBO formulation was studied, which have strong potential as thermal stabilizer to prepare super transparency and antibacterial PVC resin.
