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Growing demand for pesticides has created an environment prone to deceptive activities, where counterfeit or adulterated pesticide products infiltrate the market, often escaping rapid detection. This situation presents a significant challenge for sensor technology, crucial in identifying authentic pesticides and ensuring agricultural safety practices. Raman spectroscopy emerges as a powerful technique for detecting adulterants. Coupling the electrochemical techniques allows a more specific and selective detection and compound identification. In this study, we evaluate the efficacy of spectroelectrochemical measurements by coupling a potentiostat and Raman spectrograph to identify paraquat, a nonselective herbicide banned in several countries. Our findings demonstrate that applying -0.70 V during measurements yields highly selective Raman spectra, highlighting the primary vibrational bands of paraquat. Moreover, the selective Raman signal of paraquat was discernible in complex samples, including tap water, apple, and green cabbage, even in the presence of other pesticides such as diquat, acephate, and glyphosate. These results underscore the potential of this technique for reliable pesticide detection in diverse and complex matrices.

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The indiscriminate use of pesticides makes us susceptible to the toxicity of these chemical compounds, which may be present in high quantities in our food. It is crucial to develop inexpensive and rapid methods for determining these pesticides for government control or even for the general population. In this study, we investigated the fabrication of self-assembled LbL films using multi-walled carbon nanotubes (MWCNT) and nickel tetrasulphonated phthalocyanine (NiTsPc) as an electrochemical sensor for the herbicide Diquat (DQ). The Layer-by-Layer (LbL) assembly of the (MWCNT/NiTsPc) film was examined, along with its structural and morphological characteristics. The effect of the number of layers in DQ detection was evaluated by cyclic voltammetry, followed by the detection through differential pulse voltammetry. The achieved limit of detection was 9.62 × 10-7 mol L-1. A ~ 30% decrease in sensitivity was observed in the presence of Paraquat, a banned herbicide and electrochemical interferent due to the structural similarities, which is regularly neglected in the most published studies. The sensor was tested in real samples, demonstrating a recovery of 98.5% in organic apples.

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Herbicides are used in agriculture to control harmful crop weeds, prevent algae proliferation, and enhance macrophyte growth. Herbicide contamination of water bodies might exert toxic effects on fish in different development stages. Sperm, embryos, and adults of Astyanax altiparanae were used as a model to examine the detrimental effects of the following herbicide formulations: Roundup Transorb® (glyphosate), Arsenal® NA (imazapyr), and Reglone® (diquat). The lethal concentration 50 (LC50) values for adults using glyphosate and imazapyr were 3.14 mg/L and 4.59 mg/L, respectively, while the LC50 was higher than 28 mg/L for diquat. For the initial stages of embryo development, LC50 values were 16.52 mg/L glyphosate, 9.33 mg/L imazapyr, and 1084 mg/L diquat. Inhibition of sperm motility was noted at 252 mg/L glyphosate, 137 mg/L imazapyr, and 11,300 mg/L diquat, with an average sperm viability of 12.5%, 73.2%, and 89.3%, respectively, compared to 87.5% detected to control. A. altiparanae exhibited different sensitivities to the herbicide formulations investigated in the developmental stages evaluated. Roundup Transorb® exposure was more toxic for adults, while Arsenal® NA was most harmful for early embryonic development and inhibited sperm motility. Reglone® demonstrated low toxicity for A. altiparanae compared to Roundup Transorb® and Arsenal® NA. A. altiparanae may be considered an emerging fish model for toxicological studies for the neotropical region due to its wide distribution and biological characteristics.

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O Paraquat é um herbicida não seletivo altamente tóxico, sendo responsável por altas taxas de letalidade acidentais ou provocadas, devido, principalmente, à insuficiência respiratória. Apesar de a intoxicação por via oral ser a principal e mais grave, o contato prolongado com a substância em uma grande área corporal pode gerar uma toxicidade similar e levar ao óbito ­ fato pouco elucidado na literatura. Este é o relato de caso de um homem de 22 anos, que foi admitido em um hospital devido a queixas de mal-estar, náuseas, febre, cefaleia, dor abdominal, diarreia, queimaduras e dispneia. A suspeita diagnóstica inicial foi de hantavirose, leptospirose, dengue e tromboembolismo pulmonar e, posteriormente, foi comprovado intoxicação exógena com agrotóxico por via inalatória e cutânea. Exames de imagem revelaram fibrose pulmonar difusa e ele também apresentou alterações renais, hepáticas e coagulatórias. Como não há antídoto específico, foi empregado tratamento sintomático e suportivo, com uso de carvão ativado, antibióticos, corticoides, antioxidantes e hemodiálise. No entanto, o paciente teve uma piora progressiva do quadro, vindo a óbito devido à síndrome da angústia respiratória aguda e fibrose pulmonar. O Paraquat, embora proibido no Brasil em 2020, continua sendo utilizado de forma ilegal. Além disso, seu substituto, o Diquat, possui toxicidade semelhante. Assim, é fundamental que os profissionais da saúde reconheçam o diagnóstico da intoxicação por tais substâncias e suas diferentes vias de exposição. Também são necessárias novas medidas de fiscalização das substâncias e maior investimento em educação em saúde para evitar exposições acidentais, assim como relatado (AU).

Paraquat is a highly toxic non-selective herbicide and is responsible for high accidental or provoked lethality rates, mainly due to respiratory failure. Although oral poisoning is the primary and most severe, prolonged contact with the substance in a large body area can lead to similar toxicity and death ­ a fact that is little elucidated in the literature. This is the case report of a 22-year-old man admitted to a hospital due to complaints of malaise, nausea, fever, headache, abdominal pain, diarrhea, burns and dyspnea. The initial diagnostic suspicion was hantaviruses, leptospirosis, dengue and pulmonary thromboembolism, and there was subsequently proven exogenous intoxication with pesticides by inhalation and cutaneous route. Imaging tests revealed diffuse pulmonary fibrosis and he also had renal, hepatic and coagulation alterations. As there is no specific antidote, symptomatic and supportive treatment was performed using activated charcoal, antibiotics, corticosteroids, antioxidants and hemodialysis. However, the patient had a progressive worsening of the condition and died due to acute respiratory distress syndrome and pulmonary fibrosis. Paraquat, although banned in Brazil in 2020, continues to be used illegally. In addition, its substitute, the Diquat, has similar toxicity. Thus, it is essential that health professionals recognize the diagnosis of intoxication by such substances and their different exposure routes. New control measures for these substances and greater investment in health education are also needed to prevent accidental exposure, as reported (AU).

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On-site monitoring the presence of pesticides on crops and food samples is essential for precision and post-harvest agriculture, which demands nondestructive analytical methods for rapid, low-cost detection that is not achievable with gold standard methods. The synergy between eco-friendly substrates and printed devices may lead to wearable sensors for decentralized analysis of pesticides in precision agriculture. In this paper we report on a wearable non-enzymatic electrochemical sensor capable of detecting carbamate and bipyridinium pesticides on the surface of agricultural and food samples. The low-cost devices (

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O paraquat e o diquat são herbicidas de contacto do grupo dos bipiridilos, utilizados largamente para controlo de ervas daninhas. A importância deste grupo de herbicidas reside na sua utilização frequente para fins suicidas e pela inexistência de antídoto ou tratamento médico específico. O envenenamento com diquat é muito menos comum que com o paraquat e por isso existem poucos casos descritos na literatura. A dose letal de ambos é sobreponível, contudo o diquat é considerado menos tóxico devido ao menor dano pulmonar. Por outro lado, o diquat tem efeitos tóxicos graves sobre o sistema nervoso central. Por este motivo os sinais de neurotoxicidade pelo diquat são os mais relevantes e incluem sinais de parkinsonismo. O rim é a principal via excretora do diquat e a necrose tubular aguda é a lesão tipicamente identificada. A sobrevida depende de dois fatores: a concentração da substância no plasma e o tempo após a ingestão. O tratamento centra-se em três pontos essenciais: prevenção da absorção, rápida excreção e modificação dos efeitos tecidulares. A hemoperfusão é mais eficaz na clearance do diquat do que a hemodiálise e a sua utilização nas primeiras 12 horas de intoxicação pode reduzir a mortalidade.

Paraquat and diquat are contact herbicides from bipyridyl group, commonly used in weed control. The importance of this herbicide group is due to its frequent use with suicidal purpose and because there is neither an antidote nor a specific treatment. Poisoning with diquat is much less common that with paraquat, so there are few cases published in literature. The lethal dose of both is similar, however diquat is considered less toxic because it causes less lung damage. On the other side, diquat has severe toxic effects on central nervous system and neurotoxic signs are the more relevant, and include Parkinsonism. The kidney is the main excretory pathway of diquat and acute tubular necrosis is typical. Survival depends on two factors: plasma concentration and time of ingestion. Treatment focus in three key points: preventing absorption, rapid excretion and tissue effects. Hemoperfusion is more effective in diquat clearance than haemodialysis and its use in first 12 hours can reduce mortality.

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This work reports a study about the adsorption of the herbicides diquat and difenzoquat from aqueous medium employing polyurethane foam (PUF) as the adsorbent and sodium dodecylsulfate (SDS) as the counter ion. The adsorption efficiency was shown to be dependent on the concentration of SDS in solution, since the formation of an ion-associate between cationic herbicides (diquat and difenzoquat) and anionic dodecylsulfate is a fundamental step of the process. A computational study was carried out to identify the possible structure of the ion-associates that are formed in solution. They are probably formed by three units of dodecylsulfate bound to one unit of diquat, and two units of dodecylsulfate bound to one unit of difenzoquat. The results obtained also showed that 95% of both herbicides present in 45mL of a solution containing 5.5mgL-1 could be retained by 300mg of PUF. The experimental data were well adjusted to the Freundlich isotherm (r2 ≥ 0.95) and to the pseudo-second-order kinetic equation. Also, the application of Morris-Weber and Reichenberg equations indicated that an intraparticle diffusion process is active in the control of adsorption kinetics.

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The goal of this work was to propose a novel method for the solid-phase extraction of the herbicides diquat (DQT(2+)) and difenzoquat (DFQT(+)) from aqueous medium using polymeric Amberlite XAD-2 and XAD-4 resins in the presence of sodium dodecylsulfate (SDS). The addition of SDS to the medium was of fundamental importance in order to allow the formation of a negatively charged surface able to sorb the cationic solutes. Several factors that could influence the sorption process, such as SDS concentration in the medium, sorbent mass, pH, ionic strength, and initial concentration of the solutes were investigated. Kinetic studies were also performed to model the system and to identify the mechanisms that operate the sorption process of the herbicides. SDS concentration in the medium presented remarkable influence on the extraction efficiency, achieving maximum values when the ratios [SDS]/[herbicide] were approximately 90, for XAD-2, and 22 and 11 for DQT(2+) and DFQT(+), respectively, for XAD-4. The sorption process followed a pseudo second-order kinetic in all cases studied. It was also found that an intraparticle diffusion process controlled exclusively the sorption of the herbicides by the Amberlite XAD-2 and XAD-4 resins in the first 15 min, becoming less active with time.

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O Estado do Mato Grosso detém a maior área plantada de soja, mas perdas de produtividade vêem ocorrendo nessas áreas, não sendo consideradas as que ocorrem por manejo no momento da dessecação, cujos critérios dependem do conhecimento da cultura. Objetivou-se com este trabalho determinar a perda de produtividade de grãos ocorrida pela dessecação em estádios fenológicos antecipados, em cultivares de soja com diferentes tipos de crescimento, em relação ao tratamento sem dessecação. O experimento foi instalado na safra 2008/2009, no município de Lucas do Rio Verde, em delineamento de blocos casualizados, em esquema fatorial (4x5), representado por quatro cultivares (TMG123 RR, NK7074 RR, P98Y11 e SYN9070 RR) em quatro estádios de dessecação (R6, R6+2DD, R6+4DD e R7), além do tratamento testemunha sem dessecação. As plantas colhidas foram divididas em terço superior (TS) e terço médio e inferior (TMI), debulhadas manualmente e depois determinada a massa de 100 grãos. Concluí-se que os valores de maior massa foram obtidos nas cultivares de crescimento determinado e estes decresceram com a dessecação antecipada, aumentando linearmente com o atraso da dessecação. Existem diferentes respostas para cada cultivar causadas pela dessecação, com perdas de rendimento, sendo o terço superior o mais afetado pela dessecação, causando até 15% de perda de produtividade na cultura.

State of Mato Grosso has the largest soybean area planted, yield losses occurring in these areas, not considering the ones that occur by handling during the desiccation, the criteria adopted depend on the knowledge of the culture. The goal of this study was to determine the loss occurred by desiccation in early stages, when compared with no desiccation in soybean fields. The experiment was installed in 2008/2009 season, in the municipality of Lucas do Rio Verde, in a randomized block design in a (4x5) factorial arrangements, represented by four varieties (TMG123 RR, NK7074 RR, P98Y11 and SYN9070 RR) in four stages desiccation (R6, R6+2DD, R6+4DD and R7), and controls without desiccation. The harvested plants were divided into upper third (TS) and medium and lower third (TMI) and manually threshed and after determined the mass of 100 grains. Concluded that the values of the higher mass were obtained in cultivars of determinate growth habit, and these decreased with early desiccation, and increased linearly with the delay of desiccation. There are different answers for each cultivar caused by desiccation, with yield losses, being the upper third the most affected by desiccation, which can causing up to 15% to loss of crop productivity.

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