Detecção de metamidofós em solos por métodos ecotoxicológico e cromatografia líquida acoplada à espectrometria de massas sequencial (LC-MS/MS)

Soil contamination by pesticides is an environmental problem that needs to be monitored and avoided. However, the lack of fast, accurate and low cost analytical methods for discovering residual pesticide in complex matrices, such as soil, is a problem still unresolved. This problem needs to be solved before we are able to assess the quality of environmental samples. The intensive use of pesticides has increased since the 60s, because the dependence of their use, causing biological imbalances and promoting resistance and recurrence of high populations of pests and pathogens (upwelling). This has contributed to the appearance of new pests that were previously under natural control. To develop analytical methods that are able to quantify residues pesticide in complex environment. It is still a challenge for many laboratories. The integration of two analytical methods one ecotoxicological and another chemical demonstrates the potential for environmental analysis of methamidophos. The aim of this study was to evaluate an ecotoxicological method as "screening" analytical methamidophos in the soil and perform analytical confirmation in the samples of the concentration of the analyte by chemical method LC-MS/MS In this work we tested two soils: a clayey and sandy, both in contact with the kinetic methamidophos model followed pseudo-second order. The clay soil showed higher absorption of methamidophos and followed the Freundlich model, while the sandy, the Langmuir model. The chemical method was validated LC-MS/MS satisfactory, showing all parameters of linearity, range, precision, accuracy, and sensitivity adequate. In chronic ecotoxicological tests with C. dubia, the NOEC was 4.93 and 3.24 for ng L-1 of methamidophos to elutriate assays of sandy and clay soils, respectively. The method for ecotoxicological levels was more sensitive than LC-MS/MS detection of methamidophos, loamy and sandy soils. However, decreasing the concentration of the standard for analytical methamidophos and adjusting for the validation conditions chemical acquires a limit of quantification (LOQ) in ng L-1, consistent with the provisions of ecotoxicological test. The methods described should be used as an analytical tool for methamidophos in soil, and the ecotoxicological analysis can be used as a "screening" and LC-MS/MS as confirmatory analysis of the analyte molecule, confirming the objectives of this work

Avaliação do potencial tóxico de águas oriundas de irrigação agrícola no Baixo-Açu/RN: um problema socioambiental

For many decades the problematic raised about the indiscriminate use of pesticides in modern agriculture has incited the interest of many researchers to discover the effects caused by such products in the environment and consequently in the life of the ones which use that products (farmers) and those people who live in places next to the agricultural areas. Facing these facts, this research had the intention of comprehend the environmental perception of habitants of the Distrito Irrigado do Baixo-Açu (DIBA), located in the semiarid of Rio Grande do Norte, by using agro toxics and its possible environmental effects, as well as evaluate the levels of toxicity of waters from agricultural runoff in this region by using eco-toxicological exams with Ceriodaphnia silvestii. Were done 86 interviews with dwellers and farmers from DIBA. With the results reached in the evaluation of the interviews it was possible to identify that one of major problems is the inappropriate discard of empty packs of the pesticides used at that place. The samples collected for eco-toxicological evaluation showed a variation in its toxicity, once that the point of collect which receives waters from different cultures presented in four out of five samples toxicity for the tested species. Therefore, it concludes that the indiscriminate use of pesticides agricultural practice presented a potential to pollute to the irrigation waters, and the absence of elucidation by the farmers about the manipulation of these products contribute to the risk of environmental contamination and the possible decrease of the quality of life of the dwellers of the region