Characterization of 2,(3)-tetra-(4-oxo-benzamide) phthalocyaninato cobalt (II)—Single walled carbon nanotube conjugate platforms and their use in electrocatalysis of amitrole

An amperometric sensor composed of carbon hybrid-structure for the degradation of aminotriazole herbicide

The use of the herbicide aminotriazole (3-ATA) in agriculture poses rising concerns about global water-borne contamination. Due to its toxicity which is known to cause cancer and thyroid dysfunction, 3-ATA is considered an important analytical target. Environmental protection agencies worldwide have introduced several directives that set concentration limits for chemicals to combat water pollution. Hence, to evaluate the presence of 3-ATA in water and limit their impact on ecosystems and human health, the development of an efficient real-time monitoring device is the key. The as-synthesized copper oxide decorated multiwall carbon nanotubes at 400 °C (CuO-MWCNT@400) showed remarkable efficiency as modifiers. Under optimal conditions, we explored the direct oxidation of 3-ATA at CuO-MWCNT@400 modified carbon paste electrode (MCPE). With its distinguishing synergistic features like high levels of porosity, stability, and surface area, this structure favoured greater detection, selectivity, and sensitivity. The amperometric i-t curve technique was adopted for the first time for 3-ATA quantification. This technique rendered a good detection sensitivity of 1.65 × 10^-8 mol L^-1 and anti-interference characteristics for several interferent species, including fungicides, fertilizers, herbicides, inorganic ions, and carbohydrates. Finally, the proof-of-concept was yielded by selective and sensitive detection of 3-ATA from two different samples of spiked water. We believe this work will enhance awareness and garner appreciation of the electrochemical sensor's analytical performance in protecting our environment and water resources.

Nanostructured graphitic carbon nitride (g-C3N4)-CTAB modified electrode for the highly sensitive detection of amino-triazole and linuron herbicides

In agro-areas, linuron (LNR) and amino-triazole (ATZ) are the widely used herbicides to protect crops, but their widespread use pollutes the environment, especially when these are mixed with water or soil. In efforts to address these environmental issues and to detect trace quantities of the herbicides, a graphitic carbon nitride (g-C₃N₄) with cetyltrimethylammonium bromide (CTAB) modified carbon paste electrode (g-C₃N₄-CTAB/CPE) was developed and used for the detection of LNR and ATZ. Materials were characterized by XRD, TEM and AFM techniques. The effect of pH on electro-oxidation (under optimized conditions) showed the maximum peak current at pH of 4.2 for AMT and pH 6.0 for LNR. The electro-kinetic and thermodynamic parameters of LNR and ATZ were determined. Additional experiments were performed for the trace level detection of ATZ and LNR using the square wave voltammetric technique. Concentrations were varied linearly in the range of 3.0 × 10^-7 M to 4.5 × 10^-5 M for ATZ with a detection limit of 6.41 × 10^-8 M, and 1.2 × 10^-7 M to 3.0 × 10^-4 M for LNR with a detection limit of 2.47 × 10^-8 M. The developed novel sensor was effective for trace level detection of LNR and ATZ in water and soil samples.

Development of a colorimetric sensor array based on monometallic and bimetallic nanoparticles for discrimination of triazole fungicides

Due to the widespread use of pesticides and their harmful effects on humans and wildlife, monitoring their residual amounts in crops is critically essential but still challenging regarding the development of high-throughput approaches. Herein, a colorimetric sensor array has been proposed for discrimination and identification of triazole fungicides using monometallic and bimetallic silver and gold nanoparticles. Aggregation-induced behavior of AgNPs, AuNPs, and Au-AgNPs in the presence of four triazole fungicides produced a fingerprint response pattern for each analyte. Innovative changes to the metal composition of nanoparticles leads to the production of entirely distinct response patterns that can be used for the detection and discrimination of triazoles. Pattern recognition methods, including linear discriminant analysis (LDA) and hierarchical cluster analysis, have been employed for the differentiation of triazoles in the concentration range of 0.1-0.55 μg mL^-1. Besides, the sensor array demonstrates promising practicability to satisfactorily distinguished triazole in mixtures and complex media of wheat flour and cucumber samples. The proposed colorimetric sensor array might pave the way towards a cost-effective and rapid, yet sensitive platform for high-throughput monitoring of residual amounts of pesticides for on-site applications.

A simple electrochemical platform based on pectin stabilized gold nanoparticles for picomolar detection of biologically toxic amitrole

Amitrole is a biologically toxic nonselective herbicide which contaminates surface and ground waters at unprecedented rates. All reported modified electrodes that detect amitrole within sub-micromolar to nanomolar levels were based on the electro-oxidation of amitrole. Herein, we developed a new conceptual idea to detect picomolar concentrations of amitrole based on calcium cross linked pectin stabilized gold nanoparticle (CCLP-GNP) film modified electrode which was prepared by electrodeposition. When the electrochemical behavior of amitrole was investigated at the CCLP-GNP film, the reduction peak current of the GNPs linearly decreased as the concentration of amitrole increases. We have designed a determination platform based on the amitrole dependent decrease of the GNP cathodic peak. The described concept and high sensitivity of square wave voltammetry together facilitate the great sensing ability; as a result the described approach is able to reach a low detection limit of 36 pM which surpassed the detection limits of existing protocols. The sensor presents a good ability to determine amitrole in two linear concentration ranges: (1) 100 pM-1500 pM with a detection limit of 36 pM; (2) 100 nM-1500 nM with a detection limit of 20 nM. The preparation of CCLP-GNPs is simple, rapid and does not require any reducing agents.