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Rebelo A.M.,Federal University of Parana | Dolzan M.D.,Estacao Experimental de Itajai | Heller M.,Federal University of Santa Catarina | Deschamps F.C.,Estacao Experimental de Itajai | And 3 more authors.
Journal of the Brazilian Chemical Society | Year: 2016

The main objective of the present work was to validate a chromatographic method to determine herbicides commonly applied in the irrigated rice farming. For this, matrix-matched calibration was employed along with the extraction and clean-up of the samples by quick, easy, cheap, effective, rugged and safe (QuEChERS) method and determination of the analytes by high performance liquid chromatography tandem mass spectrometry (LC-MS/MS) with electrospray ionization in the positive mode. By this method, it was possible to achieve the ionization and detection of a total of 18 herbicides, with quantification of 12 of them. The method presented adequate precision and accuracy according to the European Commission and the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) guidelines for analytes in low concentrations. The limits of quantification ranged from 0.015 μg g-1 for oxadiazon to 0.165 μg g-1 for imazapyr. The method showed good linearity with R2 > 0.99 and recovery values from 92 to 103%. The proposed protocol is adequate for monitoring bispyribac-sodium, cyclosulfamuron, cycloxydim, clomazone, ethoxysulfuron, fenoxaprop-p-ethyl, imazapic, imazapyr, imazethapyr, metsulfuron-methyl, oxadiazon and thiobencarb in rice grains in concentrations up to 109 times lower than the maximum residue limits established by the Brazilian Health Surveillance Agency (ANVISA) for these compounds in rice samples. © 2016 Sociedade Brasileira de Química. Source

Rebelo A.M.,Federal University of Parana | Heller M.,Federal University of Santa Catarina | Dolzan M.D.,Federal University of Santa Catarina | Deschamps F.C.,Estacao Experimental de Itajai | And 3 more authors.
Analytical Methods | Year: 2014

This paper describes a method for the determination of twenty pesticides in rice grains by liquid chromatography-tandem mass spectrometry with electrospray ionization in positive mode (LC-MS/MS). The QuEChERS method was used for the extraction of pesticides and clean-up of samples. Using a phenyl-based chromatographic column and a gradient of mobile phase composed of acetonitrile-water (95/5, v/v) and formic acid 0.1%, the analytical method was optimized with a total run time of 15 min. MS/MS parameters were optimized to provide higher sensitivity for each compound, resulting in limits of detection and quantification in the ranges of 0.1-17.6 ng mL-1 and 0.4-58.8 ng mL-1, respectively. The performance of the method was also evaluated in terms of linearity, precision (instrumental, intra-assay and inter-assay), and accuracy (recovery), and then it was applied to eight commercial rice samples from different suppliers. The results demonstrated the ability of the method to detect all the 20 pesticides with precision and accuracy according to the protocols established by the most important organizations and validation guidelines. Furthermore, the limits of quantification of the method were expressively lower than the maximum residue limit (MRL) established by the Brazilian Health Surveillance Agency (ANVISA) for these pesticides in rice grains, which allow its application for monitoring real samples. © 2014 The Royal Society of Chemistry. Source

Sonego M.,Estacao Experimental de Urussanga | Peruch L.A.M.,Estacao Experimental de Urussanga | Hinz R.H.,Estacao Experimental de Itajai
Acta Horticulturae | Year: 2013

Banana is the main fruit produced in the southern coast of Santa Catarina State, Brazil. It is a crop typically grown by small farmers, employing mainly family labour. There are 8,500 ha of banana plantations in the region, with an average banana plantation size of 6 ha. Mycosphaerella leaf spots caused by Mycosphaerella musicola and Mycosphaerella fijiensis are the main foliar diseases of bananas in the region. Since November 2000, banana growers have been supported by a warning system to control Mycosphaerella leaf spots. To evaluate the warning system, the evolution of Mycosphaerella leaf spots was compared between a plantation that followed the recommendations of the warning system (Site-1) and one that did not follow the system (Site-2), from January 2005 to August 2011. The system comprises fortnightly field observation of the gross sum of leaf spots on ten plants, adequate crop management and, if necessary, pulverization with fungicide. Basic recommendations of crop management involved desuckering to keep only three plants per mat, weed control, soil fertility and defoliation. Spraying was recommended when the gross sum of leaf spots was increasing and above 800, combined with a forecast for warm and wet weather in the following days. It was found that in Site-1 the diseases were kept under control during 66% of the period against only 12% in Site-2. Two or three applications of fungicides per year were necessary to control the diseases in Site-1, compared with as many as six without such a system. This result shows that the warning system is an effective tool to help control Mycosphaerella leaf spots, even in a small plantation. Source

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