Biosensor based on atemoya peroxidase immobilised on modified nanoclay for glyphosate biomonitoring

AbstractA biosensor based on atemoya peroxidase immobilised on modified nanoclay was developed for the determination of glyphosate by the enzyme inhibition method. The inhibitor effect of the biocide results in a decrease in the current response of the hydroquinone that was used as a phenolic substrate to obtain the base signal. The biosensor was constructed using graphite powder, multiwalled carbon nanotubes, peroxidase immobilised on nanoclay and mineral oil. Square-wave voltammetry was utilised for the optimisation and application of the biosensor, and several parameters were investigated to determine the optimum experimental conditions. The best performance was obtained using a 0.1molL−1 phosphate buffer solution (pH 7.0), 1.9×10−4molL−1 hydrogen peroxide, a frequency of 30Hz, a pulse amplitude of 50mV and a scan increment of 4mV. The glyphosate concentration response was linear between 0.10 and 4.55mgL−1 with a detection limit of 30μgL−1. The average recovery of glyphosate from spiked water samples ranged from 94.9 to 108.9%. The biosensor remained stable for a period of eight weeks

Insecticide concentrations in stream sediments of soy production regions of South America

Concentrations of 17 insecticides were measured in sediments collected from 53 streams in soy production regions of South America (Argentina in 2011-2014, Paraguay and Brazil in 2013) during peak application periods. Although environmental regulations are quite different in each country, commonly used insecticides were detected at high frequencies in all regions. Maximum concentrations (and detection frequencies) for each sampling event ranged from: 1.2?7.4 ng/g dw chlorpyrifos (56-100%); 0.9?8.3 ng/g dw cypermethrin (20-100%); 0.42?16.6 ng/g dw lambda-cyhalothrin (60-100%); and 0.49?2.1 ng/g dw endosulfan (13-100%). Other pyrethroids were detected less frequently. Banned organochlorines were most frequently detected in Brazil. In all countries, cypermethrin and/or lambda-cyhalothrin toxic units (TUs), based on Hyalella azteca LC50 bioassays, were occasionally >0.5 (indicating likely acute toxicity), while TUs for other insecticides were 1 were collected from streams with riparian buffer width < 20 m. A multiple regression analysis that included five landscape and habitat predictor variables for the Brazilian streams examined indicated that buffer width was the most important predictor variable in explaining total insecticide TU values. While Brazil and Paraguay require forested stream buffers, there were no such regulations in the Argentine pampas where buffer widths were smaller. Multiple insecticides were found in almost all stream sediment samples in intensive soy production regions, with pyrethroids most often occurring at acutely toxic concentrations, and greatest potential for insecticide toxicity in streams with minimum buffer width < 20m.Fil: Hunt, Lisa. University Of California Berkeley; Estados UnidosFil: Bonetto, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Instituto de Limnología "dr. Raul A. Ringuelet". Universidad Nacional de la Plata. Facultad de Cs.naturales y Museo. Instituto de Limnología ; ArgentinaFil: Resh, Vincent H.. University Of California Berkeley; Estados UnidosFil: Forsin Buss, Daniel. Instituto Oswaldo Cruz; BrasilFil: Fanelli, Silvia Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Instituto de Limnología "dr. Raul A. Ringuelet". Universidad Nacional de la Plata. Facultad de Cs.naturales y Museo. Instituto de Limnología "dr. Raul A. Ringuelet"; ArgentinaFil: Marrochi, María Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Instituto de Limnología "dr. Raul A. Ringuelet". Universidad Nacional de la Plata. Facultad de Cs.naturales y Museo. Instituto de Limnología ; ArgentinaFil: Lydy, Michael J.. Southern Illinois University; Estados Unido