RESUMEN
The preparation of the polyaniline/CoAl-layered double hydroxide composite (PANI/CoAl-LDH) is presented by ultrasonic mixing the uniform PANI- and CoAl-LDH-building blocks, both of which are synthesized in a microemulsion system. Due to the improved surface area, increased adsorptive and catalytic sites, and enhanced conductivity, the PANI/CoAl-LDH-modified glassy carbon electrode (GCE) delivers rapid electron-transfer and mass-transfer between the substrate electrode and analytes. Consequently, PANI/CoAl-LDH/GCE demonstrates outstanding electrocatalytic activity toward carbaryl and isoprocarb with good selectivity, stability, and reproducibility. The amperometric sensor gives rise to a wide linear range of 0.1 ~ 150 µM for both carbaryl and isoprocarb at 0.19 and 0.39 V (vs. SCE), respectively. Their limits of detection are respectively 6.8 and 8.1 nM. This sensor is successfully used for the determination of carbaryl and isoprocarb pesticides in real vegetable samples with a relative standard deviation below 4%.
Asunto(s)
Aluminio/química , Compuestos de Anilina/química , Carbamatos/química , Carbaril/química , Cobalto/química , Nanoestructuras/química , Contaminantes Ambientales/química , Estructura Molecular , Plaguicidas/químicaRESUMEN
Laser-reduced graphene oxide (LRGO) on a polyethylene terephthalate (PET) substrate was prepared in one step to obtain the LRGO grid electrode for sensitive carbaryl determination. The grid form results in a grid distribution of different electrochemically active zones affecting the electroactive substance diffusion towards the electrode surface and increasing the electrochemical sensitivity for carbaryl determination. Carbaryl is electrochemically irreversibly oxidized at the secondary amine moiety of the molecule with the loss of one proton and one electron in the pH range from 5 to 7 by linear scan voltammetry (LSV) on the LRGO grid electrode with a scan rate of 300 mV/s. Some interference of the juice matrix molecules does not significantly affect the LSV oxidation current of carbaryl on the LRGO grid electrode after adsorptive accumulation without applied potential. The LRGO grid electrode can be used for LSV determination of carbaryl in fruit juices in the concentration range from 0.25 to 128 mg/L with LOD of 0.1 mg/L. The fabrication of the LRGO grid electrode opens up possibilities for further inexpensive monitoring of carbaryl in other fruit juices and fruits.
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Carbaril/química , Grafito/química , Técnicas Electroquímicas/métodos , Electrodos , Concentración de Iones de Hidrógeno , Rayos Láser , Oxidación-ReducciónRESUMEN
We describe a patterned surface-enhanced Raman spectroscopy (SERS) substrate with the ability to pre-concentrate target molecules. A surface-adsorbed nanosphere monolayer can serve two different functions. First, it can be made into a SERS platform when covered by silver. Alternatively, it can be fashioned into a superhydrophobic surface when coated with a hydrophobic molecular species such as decyltrimethoxy silane (DCTMS). Thus, if silver is patterned onto a latter type of substrate, a SERS spot surrounded by a superhydrophobic surface can be prepared. When an aqueous sample is placed on it and allowed to dry, target molecules in the sample become pre-concentrated. We demonstrate the utility of the patterned SERS substrate by evaluating the effects of inhibitors to acetylcholinesterase (AChE). AChE is a popular target for drugs and pesticides because it plays a critical role in nerve signal transduction. We monitored the enzymatic activity of AChE through the SERS spectrum of thiocholine (TC), the end product from acetylthiocholine (ATC). Inhibitory effects of paraoxon and carbaryl on AChE were evaluated from the TC peak intensity. We show that the patterned SERS substrate can reduce both the necessary volumes and concentrations of the enzyme and substrate by a few orders of magnitude in comparison to a non-patterned SERS substrate and the conventional colorimetric method.
Asunto(s)
Acetilcolinesterasa/química , Carbaril/química , Inhibidores de la Colinesterasa/química , Paraoxon/química , Espectrometría RamanRESUMEN
In this study, porous sandwich structure Fe3 O4 nanoparticles coated by polyhedral oligomeric silsesquioxanes and ß-cyclodextrin were prepared by surface polymerization and were used as the magnetic solid phase extraction adsorbent for the extraction and determination of carbaryl and carbofuran. The Fe3 O4 nanoparticles coated with polyhedral oligomeric silsesquioxanes and ß-cyclodextrin were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, vibrating sample magnetometry, and scanning electron microscopy. After optimizing the extraction conditions, a method that combined magnetic solid phase extraction with high-performance liquid chromatography was developed for the determination of carbaryl and carbofuran in apple. The method exhibited a good linearity in the range of 2-400 µg/kg for carbaryl and carbofuran (R2 = 0.9995), respectively. The limits of detection were 0.5 µg/kg of carbaryl and 0.7 µg/kg for carbofuran in apple, respectively. Extraction recoveries ranged from 94.2 to 103.1% with the preconcentration factor of 300 and the relative standard deviations were less than 5.9%. These results indicated that the method combined magnetic solid phase extraction with high-performance liquid chromatography and was promising for the determination of carbaryl and carbofuran at trace amounts.
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Carbaril/aislamiento & purificación , Carbofurano/aislamiento & purificación , Nanopartículas de Magnetita/química , Siloxanos/química , Extracción en Fase Sólida , beta-Ciclodextrinas/química , Carbaril/química , Carbofurano/química , Fenómenos MagnéticosRESUMEN
Reactive oxygen species (ROS) including singlet oxygen (1O2) and hydroxylradicals (OH) photogenerated in natural waters play important roles in indirect photolysis of man-made pollutants. This study was conducted to investigate how the generation of these two ROS influences the degradation of two highly toxic insecticides (methomyl and carbaryl) in river water. To accomplish this, the reaction rate constants of 1O2 and OH with carbaryl and methomyl were determined; the degradation rate constants of the tested insecticides in ultrapure water (direct photolysis) and in river water in the presence and absence of 1O2 and OH scavengers were also measured. The rate constants for the reaction of OH with carbaryl and methomyl were found to be (14.8⯱â¯0.64)â¯×â¯109 and (4.68⯱â¯0.52)â¯×â¯109â¯M-1â¯s-1, respectively. The reaction rate constant of 1O2 with carbaryl (2.98⯱â¯0.10)â¯×â¯105â¯M-1â¯s-1, was much higher than that of methomyl (<104â¯M-1â¯s-1). Indirect photolysis by OH accounted for 63% and 62%, while 1O2 accounted for 26% and 30% and direct photolysis accounted for 1.4% and 7% of methomyl and carbaryl degradation, respectively. The high degradation rate in river water demonstrated by both insecticides suggests that indirect photolysis mediated by OH is an important means of their degradation in river water. In addition, kinetic calculations of OH-mediated degradation rate constants of the compounds agrees with their experimentally-determined values thereby confirming the importance of OH towards their degradation.
Asunto(s)
Carbaril/química , Metomil/química , Especies Reactivas de Oxígeno/química , Contaminantes Químicos del Agua/química , Agua Dulce , Radical Hidroxilo , Cinética , Fotólisis , Ríos/química , Oxígeno SingleteRESUMEN
The characterization of soluble cholinesterases (ChEs) together with carboxylesterases (CEs) in Ficopomatus enigmaticus as suitable biomarkers of neurotoxicity was the main aim of this study. ChEs of F. enigmaticus were characterized considering enzymatic activity, substrate affinity (acetyl-, butyryl-, propionylthiocholine), kinetic parameters (Km and Vmax) and in vitro response to model inhibitors (eserine hemisulfate, iso-OMPA, BW284C51), and carbamates (carbofuran, methomyl, aldicarb, and carbaryl). CEs were characterized based on enzymatic activity, kinetic parameters and in vitro response to carbamates (carbofuran, methomyl, aldicarb, and carbaryl). Results showed that cholinesterases from F. enigmaticus showed a substrate preference for acetylthiocholine followed by propionylthiocholine; butyrylthioline was not hydrolyzed differently from other Annelida species. CE activity was in the same range of cholinesterase activity with acetylthiocholine as substrate; the enzyme activity showed high affinity for the substrate p-nytrophenyl butyrate. Carbamates inhibited ChE activity with propionylthiocholine as substrate to a higher extent than with acetylthiocoline. Also CE activity was inhibited by all tested carbamates except carbaryl. In vitro data highlighted the presence of active forms of ChEs and CEs in F. enigmaticus that could potentially be inhibited by pesticides at environmentally relevant concentration.
Asunto(s)
Anélidos/enzimología , Inhibidores de la Colinesterasa/toxicidad , Colinesterasas/química , Neurotoxinas/toxicidad , Animales , Anélidos/efectos de los fármacos , Biomarcadores/química , Carbamatos/química , Carbaril/química , Carbaril/toxicidad , Carbofurano/química , Carbofurano/toxicidad , Hidrolasas de Éster Carboxílico/antagonistas & inhibidores , Hidrolasas de Éster Carboxílico/química , Hidrolasas de Éster Carboxílico/metabolismo , Inhibidores de la Colinesterasa/química , Colinesterasas/metabolismo , Cinética , Metomil/química , Metomil/toxicidad , Neurotoxinas/químicaRESUMEN
Acetylcholinesterase (AChE) plays a vital role in nerve conduction through rapidly hydrolyzing the neurotransmitter acetylcholine (ACh) and is correlated with Alzheimer's disease. In this work, a label-free single-particle enumeration (SPE) method for the quantitative detection of acetylcholinesterase (AChE) activity is developed. The design is based on the fluorescence resonance energy transfer (FRET) between fluorescent conjugated polymer nanoparticles (FCPNPs) and MnO2 nanosheets. The fluorescence of FCPNPs can be effectively quenched by MnO2 nanosheets via hydrogen bonding interaction. In the presence of acetylcholinesterase (AChE), acetylthiocholine (ATCh) could be hydrolyzed to thiocholine (TCh), which can reduce MnO2 to Mn2+ and trigger the decomposition of MnO2 nanosheets. As a result, the fluorescence of FCPNPs is restored. Taking advantage of the superior brightness and stable fluorescence emission from individual FCPNPs, the accurate quantification of AChE is achieved by statistically counting the fluorescent particles on the glass slide surface. A linear range from 5 to 1600 µU mL-1 is obtained for AChE assay and the limit-of-detection (LOD) is 1.02 µU mL-1, which is far below the spectroscopic measurements in bulk solution. In the human serum sample, satisfactory recovery efficiencies are determined in a range of 91.0%-103.0%. Furthermore, pesticide carbaryl as an inhibitor of AChE activity was detected. The LOD is 1.12 pg mL-1 with linear responses ranging from 5 to 300 pg mL-1, which demonstrates the feasibility of this approach for AChE inhibitor screening. As a consequence, the label-free SPE-based method affords a promising platform for the sensitive detection of target molecules in the future.
Asunto(s)
Acetilcolinesterasa/análisis , Nanopartículas/química , Polímeros/química , Acetilcolinesterasa/sangre , Acetilcolinesterasa/metabolismo , Acetiltiocolina/metabolismo , Técnicas Biosensibles/métodos , Carbaril/química , Carbaril/metabolismo , Transferencia Resonante de Energía de Fluorescencia , Humanos , Límite de Detección , Compuestos de Manganeso/química , Nanopartículas del Metal/química , Óxidos/química , Plaguicidas/química , Plaguicidas/metabolismoRESUMEN
BACKGROUND: During planting, storage and transportation of maize excessive amounts of pesticides are used to ensure production, resulting in pesticide residues on the maize that can threaten human health. Plasma, compared with other technologies, has been widely regarded as a green, safe and promising technology for surface decontamination to ensure maize safety and quality. RESULTS: The aim of this study is to discuss plasma effects on the degradation of chlorpyrifos and carbaryl on maize surface and the changes of treated maize quality. Results achieved the largest degradation efficiency of chlorpyrifos and carbaryl, up to 91.5% and 73.1%, respectively. The physical changes of maize were observed by scanning electron microscopy (SEM), showing a decrease in contact angle, an increase in surface free energy and polar component, leading to improved hydrophilicity of the treated maize. There was no significant change of vitamin B2 content of maize. A significant increase of acid value and decrease of moisture content and starch content were observed within acceptable limits. CONCLUSION: It is reasonable to believe that argon plasma treatment enhances the edible safety of maize while maintaining maize quality. © 2019 Society of Chemical Industry.
Asunto(s)
Argón/farmacología , Residuos de Plaguicidas/química , Gases em Plasma/farmacología , Zea mays/química , Zea mays/efectos de los fármacos , Argón/química , Carbaril/química , Cloropirifos/química , Contaminación de Alimentos/análisis , Cinética , Control de Calidad , Riboflavina/análisis , Almidón/análisisRESUMEN
We report on the rates of decomposition of a group of N-methylcarbamate (NMC) pesticides (carbaryl, carbofuran and propoxur) under pre-determined tropical field conditions. Rates of decomposition for three NMCs were determined at pH 7.08 and T = 20 °C and pH 7.70 and T = 33 °C respectively, as follows: carbaryl (78 days and 69 days); carbofuran (143 days and 83 days) and propoxur (116 days and 79 days). Investigation on methods for removal of NMCs and their phenolic decomposition products shows that activated charcoal outperforms zeolite, alumina, diatomaceous earth, cellulose and montmorillonite clay in the removal of both NMCs and phenols from aqueous solution. Furthermore, metal complexation studies on the NMCs and phenols showed that Fe (III) forms a complex with isopropoxyphenol (IPP) within which the Fe:IPP ratio is 1:3, indicative of the formation of a metal chelate complex with the formula Fe(IPP)3.
Asunto(s)
Carbamatos/química , Metales/química , Plaguicidas/química , Plaguicidas/aislamiento & purificación , Bentonita/química , Biodegradación Ambiental , Carbaril/química , Carbaril/aislamiento & purificación , Carbofurano/química , Carbofurano/aislamiento & purificación , Celulosa/química , Arcilla/química , Hidrólisis , Fenoles/química , Propoxur/química , Propoxur/aislamiento & purificación , Soluciones/química , Clima Tropical , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/aislamiento & purificación , Zeolitas/químicaRESUMEN
This work describes, for the first time, an acryloyled ß-cyclodextrin hybrid monolith column was synthesized, under aqueous-phase conditions, and used for solid-phase microextraction of carbendazim and carbaryl. The monolithic column was characterized using scanning electron microscopy, nitrogen adsorption-desorption, thermogravimetric analysis and Fourier transform infrared spectroscopy, and used as the adsorbent for solid phase microextraction (SPME) of carbendazim and carbaryl. After optimization of the SPME conditions, a simple and sensitive SPME-HPLC method was developed for the determination of carbendazim and carbaryl in leafy vegetables. The method exhibited a good liner response in the range 5-400⯵g/kg (R2â¯=â¯0.9994) for carbendazim and 10-400⯵g/kg (R2â¯=â¯0.9996) for carbaryl, respectively. The limits of detection were 1.0 and 1.5⯵g/kg for carbendazim and carbaryl, respectively, in leafy vegetables. Recoveries ranged from 92.6% to 110.1%, and the relative standard deviations were less than 6.1%.
Asunto(s)
Bencimidazoles/química , Carbamatos/química , Carbaril/química , beta-Ciclodextrinas/química , Dióxido de SilicioRESUMEN
Chlorpyrifos (O, O-diethyl O-3,5,6-trichloropyridin-2-yl phosphorothioate) and carbaryl (1-naphthyl methylcarbamate) are often applied concurrently as insecticides in food production. The aim of this study was to research their migration behavior in a real environment. We researched the leaching of both pesticides by setting up field lysimeters on a farm with the typical soil used in fruit production today. In order to analyze the variables involved in this process, we performed complementary adsorption studies, we performed complementary adsorption studies using batches and undisturbed soil laboratory columns for both compounds. The results for pesticide transport through the lysimeters showed that less than 1% of chlorpyrifos was recovered in the leachates, while almost 17% was recovered for carbaryl. Having completed the experiment in undisturbed laboratory columns, soil analysis showed that chlorpyrifos mainly remained in the first 5 cm, while carbaryl moved down to the lower sections. These results can be explained in view of the sorption coefficient values (KD) obtained in horizons A and B for chlorpyrifos (393 and 184 L kg-1) and carbaryl (3.1 and 4.2 L kg-1), respectively. By integrating the results obtained in the different approaches, we were able to characterize the percolation modes of these pesticides in the soil matrix, thus contributing to the sustainable use of resources.
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Carbaril/análisis , Cloropirifos/análisis , Contaminantes del Suelo/análisis , Suelo/química , Adsorción , Carbaril/química , Cloropirifos/química , Insecticidas/análisis , Insecticidas/química , Contaminantes del Suelo/químicaRESUMEN
Water quality assessment was conducted on the Ruiru River, a tributary of an important tropical river system in Kenya, to determine baseline river conditions for studies on the aquatic fate of N-methyl carbamate (NMC) pesticides. Measurements were taken at the end of the long rainy season in early June 2013. Concentrations of copper (0.21-1.51 ppm), nitrates (2.28-4.89 ppm) and phosphates (0.01-0.50 ppm) were detected at higher values than in uncontaminated waters, and attributed to surface runoff from agricultural activity in the surrounding area. Concentrations of dissolved oxygen (8-10 ppm), ammonia (0.02-0.22 ppm) and phenols (0.19-0.83 ppm) were found to lie within normal ranges. The Ruiru River was found to be slightly basic (pH 7.08-7.70) with a temperature of 17.8-21.2°C. The half-life values for hydrolysis of three NMC pesticides (carbofuran, carbaryl and propoxur) used in the area were measured under laboratory conditions, revealing that rates of decay were influenced by the electronic nature of the NMCs. The hydrolysis half-lives at pH 9 and 18°C decreased in the order carbofuran (57.8 h) > propoxur (38.5 h) > carbaryl (19.3 h). In general, a decrease in the electron density of the NMC aromatic ring increases the acidity of the N-bound proton removed in the rate-limiting step of the hydrolysis mechanism. Our results are consistent with this prediction, and the most electron-poor NMC (carbaryl) hydrolyzed fastest, while the most electron-rich NMC (carbofuran) hydrolyzed slowest. Results from this study should provide baseline data for future studies on NMC pesticide chemical fate in the Ruiru River and similar tropical water systems.
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Carbamatos/análisis , Plaguicidas/análisis , Contaminantes Químicos del Agua/análisis , Calidad del Agua , Carbamatos/química , Carbaril/análisis , Carbaril/química , Carbofurano/análisis , Carbofurano/química , Semivida , Hidrólisis , Kenia , Propoxur/análisis , Propoxur/química , Lluvia , Ríos/química , Estaciones del Año , Relación Estructura-Actividad , Clima TropicalRESUMEN
Biochars that were produced from three different biomass materials were amended to a soil to elucidate their influence on the fate of carbaryl. Sorption and degradation of carbaryl in soils amended with the biochars were investigated. The results showed that the amendment of biochars to soil enhanced the sorption of carbaryl. The nonlinearity of sorption isotherm and sorption affinity of carbaryl increased with the content and pyrolytic temperature of the biochars. Both chemical and biological degradation of carbaryl were influenced by biochars. The biochars enhanced the chemical hydrolysis of carbaryl in soil, with biochars produced at 700 °C (BC700) exhibiting greater impact, due to their strong liming effect. In contrast, BC350 (produced at 350 °C) promoted the biodegradation of carbaryl in soil by different extents, while BC700 obviously reduced the biodegradation of carbaryl. The enhanced activities of natural microorganisms in the soil and the lowered bioavailability of carbaryl acted together to determine the biodegradation.
Asunto(s)
Carbaril/química , Carbón Orgánico/química , Restauración y Remediación Ambiental/métodos , Contaminantes del Suelo/química , Adsorción , Restauración y Remediación Ambiental/instrumentación , Suelo/química , TemperaturaRESUMEN
In recent times, an increased occurrence of neurodevelopmental disorders, such as neurodevelopmental delays and cognitive abnormalities has been recognized. Exposure to pesticides has been suspected to be a possible cause of these disorders, as these compounds target the nervous system of pests. Due to the similarities of brain development and composition, these pesticides may also be neurotoxic to humans. We studied two different pesticides, chlorpyrifos and carbaryl, which specifically inhibit acetylcholinesterase (AChE) in the nervous system. The aim of the study was to investigate if the pesticides can induce neurotoxic effects, when exposure occurs during a period of rapid brain growth and maturation. The results from the present study show that both compounds can affect protein levels in the developing brain and induce persistent adult behavior and cognitive impairments, in mice neonatally exposed to a single oral dose of chlorpyrifos (0.1, 1.0 or 5mg/kg body weight) or carbaryl (0.5, 5.0 or 20.0mg/kg body weight) on postnatal day 10. The results also indicate that the developmental neurotoxic effects induced are not related to the classical mechanism of acute cholinergic hyperstimulation, as the AChE inhibition level (8-12%) remained below the threshold for causing systemic toxicity. The neurotoxic effects are more likely caused by a disturbed neurodevelopment, as similar behavioral neurotoxic effects have been reported in studies with pesticides such as organochlorines, organophosphates, pyrethroids and POPs, when exposed during a critical window of neonatal brain development.
Asunto(s)
Carbaril/toxicidad , Cloropirifos/toxicidad , Síndromes de Neurotoxicidad/patología , Plaguicidas/toxicidad , Acetilcolinesterasa/metabolismo , Animales , Conducta Animal/efectos de los fármacos , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Carbaril/química , Sistema Nervioso Central/efectos de los fármacos , Sistema Nervioso Central/patología , Cloropirifos/química , Inhibidores de la Colinesterasa/toxicidad , Homólogo 4 de la Proteína Discs Large , Femenino , Proteína GAP-43/metabolismo , Guanilato-Quinasas/metabolismo , Masculino , Proteínas de la Membrana/metabolismo , Ratones , Ratones Endogámicos , Receptores AMPA/metabolismo , Sinaptofisina/metabolismo , Proteínas tau/metabolismoRESUMEN
A fluorescent calix[4]arene triazole-linked pyrene (CP) was carefully designed and synthesized via click chemistry. The modification of CP with graphene oxide (GO) by a simple non-covalent interaction strategy is presented. Further inspection by electrochemical impedance spectroscopy reveals that the CP-GO could exhibit a very high supramolecular recognition for carbaryl, in particular in serum samples with a nanomolar concentration detection. Additionally, it is easy to directly observe macroscopic recognition by the contact angle, and expand practical applications.
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Calixarenos/química , Carbaril/sangre , Técnicas de Química Analítica/instrumentación , Colorantes Fluorescentes/química , Grafito/química , Fenoles/química , Pirenos/química , Triazoles/química , Carbaril/química , Química Clic , Modelos Moleculares , Conformación MolecularRESUMEN
Carbaryl is a low molecular weight insecticide that inhibits cholinesterase. Residues of carbaryl in food and the environment have damaged human health. A high-speciï¬city scFv that can identify carbaryl is still lacking. In the present study, an anti-carbaryl scFv gene was prepared by cloning VL and VH genes from hybridoma cells secreting monoclonal antibody, then VH and VL were fused together using splicing by overlap extension (SOE) PCR with a flexible polypeptide linker connector (Gly4Ser)3, and then the scFv-pET-26b recombinant plasmid was constructed and transformed into E. coli BL21 for expression using IPTG as an inducer. The expressed recombinant protein was identified by SDS-PAGE and ELISA. The three-dimensional structure of the anti-carbaryl scFv was constructed by computer modeling, and carbaryl was docked to the scFv model to obtain the structure of the binding complex. The binding site was composed of Ala51, Ser52, Ile51, Gly54, Ser56, Arg98, and Gly100. This helps to understand the mechanism of interaction between anti-carbaryl antibody and antigen. Furthermore, it provides guidance for in vitro affinity maturation of anti-carbaryl antibody.
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Carbaril/química , Insecticidas/química , Anticuerpos de Cadena Única/química , Carbaril/antagonistas & inhibidores , Humanos , Insecticidas/antagonistas & inhibidores , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Anticuerpos de Cadena Única/biosíntesis , Anticuerpos de Cadena Única/genéticaRESUMEN
Head lice infestation (or pediculosis) is an important public health problem in Thailand, especially in children between the ages 5 and 11 years. Head lice resistance is increasing, chemical pediculicides have lost their efficacy, and, therefore, alternative pediculicides such as herbal shampoos have been proposed to treat head lice infestation. Thus, the present study investigated the efficacy of three herbal shampoos based on native plants in Thailand (Acorus calamus Linn., Phyllanthus emblica Linn., and Zanthoxylum limonella Alston) against head lice and compared them with carbaryl shampoo (Hafif shampoo, 0.6% w/v carbaryl), malathion shampoo (A-Lice shampoo, 1.0% w/v malathion), and commercial shampoos (Babi Mild Natural' N Mild and Johnson's baby shampoo) in order to assess their in vitro and in vivo efficacy. For in vitro study, doses of 0.12 and 0.25 ml/cm(2) of each herbal shampoo were applied to filter paper, then 10 head lice were place on the filter paper. The mortalities of head lice were recorded at 5, 15, 30, and 60 min. The results revealed that all herbal shampoo were more effective on pediculicidal activity than chemical and commercial shampoos with 100% mortality at 15 min; LT50 values ranged from 0.25 to 1.90 min. Meanwhile, chemical shampoos caused 20-80% mortality, and LT50 values ranged from 6.50 to 85.43 min. On the other side, commercial shampoos showed 4.0% mortality. The most effective pediculicide was Z. limonella shampoo, followed by A. calamus shampoo, P. emblica shampoo, carbaryl shampoo, malathion shampoo, and commercial shampoo, respectively. In vivo results showed that all herbal shampoos were also more effective for head lice treatment than chemical and commercial shampoos with 94.67-97.68% of cure rate after the first treatment; the second treatment, 7 days later, revealed that the cure rate was 100%. Meanwhile, chemical shampoo showed 71.67-93.0% of cure rate and, unfortunately, commercial shampoos were nontoxic to head lice and showed 0% of cure rate after the first and the second treatments. Our data showed that three herbal shampoos of native plants in Thailand in this study are suitable to be used as pediculicides for Thai children since it is safe for children and there is no side-effect after application.
Asunto(s)
Preparaciones para el Cabello/farmacología , Insecticidas/farmacología , Infestaciones por Piojos/tratamiento farmacológico , Pediculus/efectos de los fármacos , Phthiraptera/efectos de los fármacos , Acorus , Animales , Antiparasitarios/farmacología , Carbaril/química , Carbaril/farmacología , Niño , Preescolar , Preparaciones para el Cabello/química , Humanos , Infestaciones por Piojos/parasitología , Malatión/química , Malatión/farmacología , Phyllanthus emblica/química , Tailandia/epidemiología , Zanthoxylum/químicaRESUMEN
A novel nonenzymatic sensor based on cobalt (II) oxide (CoO)-decorated reduced graphene oxide (rGO) was developed for the detection of carbofuran (CBF) and carbaryl (CBR). Two well-defined and separate differential pulse voltammetric peaks for CBF and CBR were obtained with the CoO/rGO sensor in a mixed solution, making the simultaneous detection of both carbamate pesticides possible. The nonenzymatic sensor demonstrated a linear relationship over a wide concentration range of 0.2-70 µM (R=0.9996) for CBF and 0.5-200 µM (R=0.9995) for CBR. The lower detection limit of the sensor was 4.2 µg/L for CBF and 7.5 µg/L for CBR (S/N=3). The developed sensor was used to detect CBF and CBR in fruit and vegetable samples and yielded satisfactory results.
Asunto(s)
Carbaril/química , Carbofurano/química , Electroquímica/instrumentación , Frutas/química , Verduras/química , Electroquímica/métodos , Grafito , Óxidos , PlaguicidasRESUMEN
In this paper, the important issue of the desorption of less- and nonvolatile compounds with minimal sample decomposition in ambient mass spectrometry is approached using ambient flash desorption mass spectrometry. The preheated stainless steel filament was driven down and up along the vertical axis in 0.3 s. At the lowest position, it touched the surface of the sample with an invasion depth of 0.1 mm in 50 ms (flash heating) and was removed from the surface (fast cooling). The heating rate corresponds to ~10(4) °C/s at the filament temperature of 500 °C. The desorbed gaseous molecules were ionized by using a dielectric barrier discharge ion source, and the produced ions were detected by a time-of-flight (TOF) mass spectrometer. Less-volatile samples, such as pharmaceutical tablets, narcotics, explosives, and C60 gave molecular and protonated molecule ions as major ions with thermal decomposition minimally suppressed. For synthetic polymers (PMMA, PLA, and PS), the mass spectra reflected their backbone structures because of the suppression of the sequential thermal decompositions of the primary products. The present technique appears to be suitable for high-throughput qualitative analyses of many types of solid samples in the range from a few ng to 10 µg with minimal sample consumption. Some contribution from tribodesorption in addition to thermal desorption was suggested for the desorption processes. Figure á
Asunto(s)
Calor , Espectrometría de Masas/métodos , Carbaril/análisis , Carbaril/química , Fenómenos Químicos , Sustancias Explosivas/análisis , Iones , Ácido Láctico/análisis , Loratadina , Narcóticos/análisis , Poliésteres , Polímeros/análisis , Poliestirenos/análisis , Acero Inoxidable , Tetraciclina/análisisRESUMEN
The irreversible sorption-desorption of carbaryl in five soil types with crop-residue-derived biochar (CBC) amendment was determined. CBC has lower surface area and micropores volume than wood-based biochar and charcoal. However, CBC amendment (0.5%) still significantly enhanced the hysteresis effect on soils, with a 1.7- to 2.8-fold increase in the hysteresis index (HI) values. The HI values increased exponentially with the increased amount of CBC but decreased exponentially with the increased amount of soil organic matter (SOM%). Furthermore, the irreversible carbaryl sorption (qirr) and the irreversibility index (Iirr) values were proportional to the amount of CBC (0-1.0%) in soils. Likewise, the SOM-rich soil (S3) was washed ten times to reduce its SOM% to evaluate the influence of the dissolved organic matter (DOM) in the soils on the irreversible sorption. The Iirr values of the unamended S3 increased as the number of sorption-desorption cycles increased, whereas those of the 1.0% CBC-amended S3 decreased. In addition, the Iirr values of the unwashed S3 were lower than those of the washed S3. By contrast, the Iirr values of the 1.0% CBC-amended S3 soil were higher in the unwashed samples than in the washed samples. These results suggested that DOM had opposite effects on the irreversible carbaryl sorption by unamended and CBC-amended soils. The DOM release may expose more irreversible adsorption sites in the soils and may cover the surface of the CBC to form a desorption-resistant fraction in its mesopore or macropore regions, thereby preventing the desorption of adsorbed carbaryl molecules.