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Introducción: El clorotalonil se puede determinar por varias técnicas de análisis, entre ellas la cromatografía de gases (GC) y cromatografía líquida de alta resolución (HPLC). Estas dos técnicas son las de mayor uso en los laboratorios Objetivo: Comparar la eficacia de las metodologías analíticas por GC y por HPLC para la determinación de clorotalonil en un fungicida comercial. Métodos: aplicamos ambos métodos a muestras equivalentes y comparamos los resultados con pruebas estadísticas. Resultados: ambos métodos arrojaron resultados estadísticamente equivalentes y confiables. Estos parámetros fueron satisfactorios: selectividad, ámbito de trabajo y linealidad, límite de detección y cuantificación, repetibilidad, precisión intermedia, robustez, veracidad y sesgo; los consideramos lineales, precisos y exactos que cumplen con las normas del Ente Costarricense de Acreditación (ECA). Conclusiones: ambos métodos para determinación de clorotalonil se pueden utilizar de manera confiable bajo las condiciones definidas.

Chlorothalonil (CHT) is a chlorinated-nitrogen fungicide used in the control of black sigatoka, a disease that affects banana and plantain, has adverse effects on the environment and its metabolites can be toxic. The CHT has been the object of several studies related to its behavior and degradation in the environment; however, few works have been developed in tropical areas, such as the case of the banana zone of Magdalena - Colombia. In addition, it is unknown if the microbial diversity existing in these soils can transform compounds such as CHT, thus these microorganisms can be the basis for the implementation of remediation strategies based on bioaugmentation. In this sense, the present study aims to evaluate the degradation of CHT in soils of a tropical coastal zone, under conditions of natural attenuation and bioaugmentation with native microorganisms. For this purpose, microorganisms capable of growing with CHT as their sole carbon source (10.8 mg.l-1) and tolerating a concentration up to 25 mg.l-1 were isolated and selected from soils in the Magdalena-Colombia banana zone. Subsequently, CHT degradation tests (2000 ng.g-1) were performed on experimental plots, with bioaugmentation of native microorganisms and natural attenuation during 35 days, evaluating the growth of microbial populations and the degradation of CHT by gas chromatography associated with a mass spectrometry detector (GC/MS). Because of the microbial selection process, 8 morphotypes were obtained with the ability to grow in CHT as the sole carbon source and tolerate concentrations up to 25 g.l-1. The isolates were identified by sequencing the 16S rDNA gene as belonging to the genera Enterobacter, Klebsiella, Pseudomonas and Citrobacter. The CHT degradation tests showed that under bioaugmentation conditions with the native microorganisms selected in the study, a 100% reduction was achieved after 21 days; while under natural attenuation conditions after 35 days the degradation reached values of 98.5%. The application of bioaugmentation of selected and enhanced bacteria increased the rate of pesticide degradation by ~2.5 times, reducing the half-life from 6.2 to 2.5 days. The results demonstrated the effectiveness of the bioaugmentation treatment and that the selected consortium may be useful for bioremediation of banana crops soils contaminated with the fungicide. [ABSTRACT FROM AUTHOR]

The effect of the treatment with the fungicide chlorothalonil on radical mycorrhizal colonization on barley seed was evaluated. An experiment was performed, the factors were as follows: 1) Mycorrhiza INIFAP® (uninoculated, one, two and three doses) and fungicide (with and without fungicide). Monthly sowings were conducted to determine the degree of colonization in the roots. The results showed that treatment of the seed with chlorothalonil was not significantly decreased by the radical mycorrhizal INIFAP® colonization, chlorothalonil treatment had a mean of 32.63% root infection whereas without chlorothalonil was 36.46%. When the seed was treated with chlorothalonil, the more affected in terms of root colonization by mycorrhizal INIFAP® was a dose, treatment with double and triple doses showed no significant difference between them. Storage of seed infection percentage decreased progressively. Through the time of the inoculated seed storage, root infection by mycorrhizal INIFAP® remained constant and unchanged for the first six months, but then decreased at ca. 50% over a period of 10 months, when treated or not treated with fungicide.

O uso intensivo de agrotóxicos em culturas de tomates tem causado preocupações quanto à provável contaminação do produto final. Este trabalho teve como objetivo monitorar, por dois anos consecutivos, em quatro propriedades de uma área altamente tecnificada, o uso de agrotóxicos em tomate irrigado durante seu desenvolvimento, quantificar os resíduos dos principais princípios ativos utilizados, e avaliar o grau de contaminação dos frutos colhidos. Foram analisados metamidofós, clorpirifós, captan, clorotalonil, endosulfan, lambda-cialotrina, e cobre. Para avaliar o grau de contaminação dos frutos foi validado um método de análise de resíduos múltiplos capaz de quantificar esses compostos. Os resíduos encontrados foram de fungicidas e inseticidas aplicados nas fases de frutificação e maturação: captan, 0,35 mg/kg, na Fazenda 2; clorotalonil, 0,16 mg/kg e 0,95 mg/kg, nas Fazendas 1 e 2, respectivamente; lambda-cialotrina, 0,03 mg/kg, na Fazenda 2; cobre, 2,03 mg/kg, 3,75 mg/kg e 1,44mg/kg, nas Fazendas 1, 2 e 3, respectivamente, e 0,95 mg/kg, 1,70 mg/kg e 2,31 mg/kg, na Fazenda 4. Não ocorreram resíduos dos inseticidas organofosforados, aplicados principalmente durante o desenvolvimento vegetativo da cultura. Não houve contaminação dos tomates pelos agrotóxicos analisados. Os resíduos que devem ser monitorados são os dos agrotóxicos aplicados na fase de maturação da cultura.The intensive use of pesticide in tomato crops have been causing concern about a possible contamination of the final product. This work aimed at monitoring, for two years, in four farms located in a high technology area, the use of pesticides in irrigated tomato crops, quantifying the main active ingredient residues and evaluating the contamination level of the fruits. The components analised were: methamidophos, chlorpyrifos, captan, chlorothalonil, endosulfan, lambda-cyhalothrin and copper oxychloride. In order to evaluate the contamination level, a multiresidue method was validated. The residues found were from fungicides and insecticides used during the frutification and maturation stages of the crop: captan, 0.35 mg/kg, at Farm 2; chlorothalonil, 0.16 mg/kg and 0.95 mg/kg, at Farms 1 and 2, respectively; lambda-cyhalothrin, 0.03 mg/kg, at Farm 2; copper, 2.03 mg/kg, 3.75 mg/kg and 1.44 mg/kg, at Farms 1, 2 and 3, respectively, and 0.95 mg/kg, 1.70 mg/kg and 2.31 mg/kg, at Farm 4. Residues of organophosphorous components applied mainly during the vegetative growing were not found. There was no contamination in the tomatos. The residues to be monitored are those from the pesticides used in the crop maturation stage.