PESTICIDES

Author: RODRÍGUEZ SÁNCHEZ MARIANO.
Year: 2003.
University: ALMERÍA [www.ual.es].
Place of defense: FACULTAD DE CIENCIAS EXPERIMENTALES.
Place of preparation: UNIVERSIDAD DE ALMERIA.

Summary: In this paper we develop and evaluate two methods of extraction using a multi-organic solvent and Supercritical Fluid Extraction with (SFE), pair the determination of pesticides Bromopropilato `, captafol, Clortalonil, p, p'-DDE, p, p ' - DDT, deltamethrin, gamma-HCH, Iprodiona, Permethrin, Procimidona, Triclorfon and Vinclozolina by Gas Chromatography with detector capture Electrones (GC-ECD) in cereals and pulses (rice, wild rice, barley, lentils, maize and wheat). First developed and evaluated a method of extracting multi with ethyl acetate. This method of extraction with ethyl acetate was validated for all combinations pesticide / matrix studied using standards prepared to extract matrix. Thus, in most cases rates of recovery were obtained between 70 and 120%, and coefficients of variation of 20% lower. We studied the so-called "matrix effect", which was observed for these pesticides in almost all matrices. Pesticides and matrices that showed a lower tendency to portray this effect fueorn p, p'-DDE, deltamethrin, gamma-HCH and Pemetrína and wild rice, barley and wheat, respectively. Secondly developed and evaluated a method with CO2 supercritical extraction (SFE) as a method of extraction alternative to traditional methods based on extraction with organic solvents such as that described above. With conditions extraction finally selected (15 ml CO2 50Â ° C, 200 atm, 200 ul of methanol as a modifier static, 1 minute static extraction and 5 ml ethyl acetate solvent as collector), it validated the method SFE on arrays of rice, wild rice, wheat and lentils, obtaining recoveries average of between 70% and 100%, except in four combinations of pesticide / Matrix: Clortalonil / lentils, obtaining recoveries average of between 70% and the 100% except in four combinations of pesticide / Matrix: Clortalonil / lentils, p, p '-DDT/lentejas and p, p'- DDT / wheat. The coefficients of variation (CV%) obtained were generally less than 20%, except in the case of p, p '-DDT in lentils and wheat. With these results has been demonstrated that the technique SFE is a valid alternative to conventional extraction methods to be applied to the analysis of multi pesticides in cereals.

Author: CRUZ-GUZMÁN ALCALÁ MARTA.
Year: 2004.
University: SEVILLA [www.us.es].
Place of defense: INSTITUTO DE RECURSOS NATURALES Y AGROBIOLOGÍA DE SEVILLA (CSIC).
Place of preparation: IRNAS (CSIC) Y FACULTAD DE QUÍMICA (SEVILLA).

Summary: To date, most research in organoarcillas has interacted with large organic cations without specific functional groups, such as cations alquilamonio, paying much less attention to the modified clays with organic cations with polar functional groups. Ions organic functional groups selected may allow elective modifications of the surface of the clay mineral, according to the structural formula of pesticide to absorb, and might even give the organoarcillas nature of absorbent double affinity with both heavy metals ( thanks to its polar functional group) as a pesticide (by selectively or non-selectively functionality through hydrophobic interactions). Most recently, Sheng et al. (1999) described a dual absorbent lead and chlorobenzenes exchanging cations carboxideciltrietilamonio by inorganic cations of montmorillonite, thus a simultaneous retention of both pollutants. In addition, organic cations with low toxicity or natural origin would be of particular interest. The naturalness of remediation techniques has been sought, in the scientific literature, not only to reduce the toxicity that may add to the medium using these techniques, but because of its low cost and ubiquity, something very important in optimizing the methods of decontamination. Within this context, the overall objective of this study was to assess the feasibility of developing organoarcillas from naturally occurring organic cations with various functional groups in their structures and characterize the properties adsrobentes of orgnaoarcillas arising for various pesticides and heavy metals. After the synthesis and evaluation of the capability of absorbing the organoarcillas for different pollutants, experiments were carried out to evaluate its potential usefulness in the immobilization of contaminants in soils and to act as media in controlled-release formulations of pesticides. For the preparation of modified clays were selected two montomorillonitas with different loads laminates, four organic cations and two naturally occurring organic cation type alquilamonio used for comparative purposes. The contaminants were selected six pesticides with various physicochemical characteristics (simazine, hexazinona, triadimefon, alaclor, carbaryl and imazetapir) and heavy metals Pb and Hg. The studies were supplemented with heavy metals to characterize the adsorption of the same subject matter articulated by colloidal prepared in the laboratory from three of the most active components of the soil in the process of adsorption (montmorillonite, iron oxide and acid húmico). The results obtained over the development of this report we suggest the following conclusions: 1-Cationes organic polar functional groups such as those used in this study, L-carnitine, ethyl ester of cysteine, dimethyl ester of cystine and thiamin, can be incorporated in the montomorillonitas by simple cation exchange reactions similar to those used to prepare the organoarcillas with cations of the type alquilamonio. 2 - The yield of the reaction of cation exchange for carnitine, cysteine, cystine and thiamine was greater for cations cations divlaentes that without acid groups, probably because the ionization of these leads to repulsiones with the surface of the clay mineral . 3 - The incorporation of organic cations used in the present study takes place in the interlaminar space of montmorillonitas with a reduction of water hydration of these and gracious surface measured by nitrogen adsorption. 4-adsorption experiments of pesticides on organoarcillas prepared 8 sa part 1c2a go cation organic funcionalizados showed that the ability of organoarcillas for acquiring a particular pesticide depends on: A laminar-load of clay. B-size organic cation. C - The amount of organic cation incorporated. D-chemical nature of the organic cation and the pesticide in question. These parameters determine the presence of empty spaces and possible mechanisms of interaction between the pesticide and organoarcilla. 5 - The chemical nature of the organic cation seems to affect the absorbent properties of the organoarcilla by the presence of a combination of functional groups that interact specifically with the molecule pesticide and also by the effects esteóricos produced by the kind of union between the clay and organic cation depending on the chemical characteristics of the latter. This suggests the possibility of creating a microenvironment interlaminar designed to optimize the affinity of organoarcillas for a particular pesticide. 6 - The chemical nature of the organic cation affects not only the ability of organoarcillas but absorbent to the desroción. In general, organoarcillas with higher affinity for pesticides also showed greater resistance to the takeover, probably by the contribution of polar interactions of the adsorption process. 7 - The results of immobilization of pesticides in soil suspensions treated and untreated with organoracillas indicate that the effectiveness of the same organoarcilla as inmovilizante of a particular pesticide varies depending on the type of soil to which it applies. For example, the addition of organoarcilla SW-CAR a calcareous soil causes desprotonación of organic cation, reducing their effectiveness in retaining deplaguicidas commodities, while its addition to acidic soils significantly increases the effectiveness of organoarcilla as inmovilizante. These results suggest that the selection of organoarcilla better as inmovilizante of a particular pesticide must not only agree with the affinity of the pesticide by the organoarcilla but also taking into account the characteristics of the soil to be treated. 8-Experiments leaching of pesticides in soil treated and untreated with organoarcillas funcionalizadas soil can be used to delay the leaching of pesticides. This delay of leaching could be particularly interesting in the long term residence of the pesticide in the surface soil horizons more and thus prolong its activity, reducing the risk of contamination of aquifers and / or provide the time needed for improving the effectiveness of additional decontamination techniques. 9 - The results of the kinetics of release into water, leaching experiments in columns and bioassays with preparations organoarcillas-plaguicidas suggest using organoarcillas funcionalizadas as carriers for slow release formulations of pesticides in a manner similar to that suggested for organoarcillas with cations of the type alquilamonio. The specificity of organoracillas funcionalizadas and use of organic cations natural, non-toxic, in the preparation of these organoarcillas would two major advantages regarding the use of organoarcillas traditional. 10-adsorption experiments were carried out with heavy metals Pb (II) and Hg (II) show that the presence of polar functional groups in organoarcillas prepared from carnitine, cysteine, cystine and thiamine give them a character of absorbent double lacking the organoracillas prepared from cations alquilamonio as hexadeciltrimetilamonio and feniltrimetilamonio. It is therefore possible to select the catiónorgánico form containing functional groups with affinity not only for certain pesticides, but also for certain heavy metals. 11-freezing experiments of Hg (II) in suspensions of treated and untreated soils with organoarcillas prepared from cysteine and cystine show that organoarcillas expands capacity absorbent soil and thus may be useful as inmovilizantes this metal . 12 - The low vertical movement of Hg (II) in soil columns indicated a low risk of contamination of groundwater. However, the addition of organoarcilla funcionalizada SW-CISTI led to a decline in the fraction of HCI with removable Hg in the soil at the end of the leaching experiment, which suggests a reduced availability of the metal after the addition of organoarcilla. 13 - The process of association between the components of soil active in the processes of adsorption may influence largely on the ability of the absorbent colloids organominerales natural so that the absorbent ability of these may not correspond to what was expected from the sum the absorptive capacity of the individual components. To deepen the understanding of the processes of association could help improve the prediction of the process of adsorption of pollutants in the soil, the prediction of risk and the choice of retrieval techniques most suitable for soil contaminants. In summary, the results of this study show that the presence of functional groups in the organic cation influences the capacity and selectivity of the adsorption of organoarcillas for pesticides, so that a proper selection of chemical characteristics of the organic cation can to optimize the properties of absorbent as organoarcillas respect to the use of organic cation type alquilamonio, ca pray in general for such specificity. Moreover, the presence of functional groups in the organic cation favors the affinity of organoarcilas by inorganic contaminants such as heavy metals, and gives them a character of "double adsorbent" lacking the organoarcillas classical prepared from cation type alqilamonio. The results of the experiments of this study show that organoarcillas well prepared could be potentially useful as inmovilizantes of pesticides and heavy metals in soils, delaying its movement toward groundwater as well as carriers in slow release formulations of pesticides. The feasibility of incorporating natural organic cations to prepare organoarcillas funcionalizadas is particularly interesting in terms of minimizing the impact of absorbing once added to the soil or aquifer.

Author: Rubio Muñoz Ana.
Year: 2005.
University: MURCIA [www.um.es].
Place of defense: Facultad de Química. Universidad de Murcia.
Place of preparation: Facultad de Química. Universidad de Murcia.

Summary: The work provides information on various aspects of the mobility and disappearance of some pesticide residues widely used in agriculture (herbicides, insecticides and fungicides), by conducting separate experiences together make up a thorough job that can be summarized as follows: - Validation of the analytical methodology necessary for the determination of pesticides in order to study the different substrates used in the conduct of experimental work by uilización procedures microextracción on line and chromatography techniques for the determination of pesticide residues studied the different arrays. - Study of leaching herbicides benfluralina, propyzamide and pendimethalin, which is widely used in horticultural soils in the region through laboratory tests on soil columns under controlled conditions leaching. - Know the process of absorption of the insecticide chlorpyrifos and chlorpyrifos-methyl, and the fungicide penconazol, different varieties of native wetland macrophytes Mediterranean, selecting species and varieties and most representative study of the absorptive capacity of their leaves, different conditions of particle size and dehydration. - Influence of material céreo present in the leaf surface of three species of macrophytes and orange in the photodegradation of the insecticide chlorpyrifos added as a subject and as formulated in a laboratory Experimenting with different surfaces plant and modeling of such experiences in Petri dishes to test the photolytic degradation of the pesticide selected. - Evaluation of mobility and dilution of the insecticide and fungicide referred to in paragraph three, in surface water using a pilot channel. Performing studies dilution of insecticides and fungicides in a pilot channel to check the mobility of the products studied by direct application to the soil before moving water for the canal and also by direct application to water the same at the beginning of his tenure by controlled areas.

Author: IBAÑEZ MARTINEZ MARIA.
Year: 2006.
University: JAUME I DE CASTELLON [www.uji.es].
Place of defense: FACULTAD DE CIENCIAS JURIDICAS Y ECONOMICAS.
Place of preparation: ESCUELA SUPERIOR DE TECNOLOGIA Y CIENCIAS EXPERIMENTALES.

Summary: Within the environmental issues, pesticides are possibly one of the families of pollutants of most concern at present, due to its high toxicity and use around the globe, as well as the possibility of contamination of different types of samples ( soil, water, air, food products). The high number of pesticides currently in use, along with the great variability that presented in terms of their physico-chemical properties, significantly hampers the analysis level waste. Although there have been numerous environmental studies, the majority of programs to control these pollutants, both in the environment and in food or living beings exposed, focus on only a few products (usually the pesticide unchanged), despite some products that are known for conversion / metabolites relatively stable, persistent and toxic. This widespread lack of information about the presence of transformation products (TPs) in the environment is due mainly to the lack of analytical methodology. Thus, it seems necessary to generate information on routes degradation / transformation of these compounds, develop analytical methodology to determine their levels in the environment, and assess their impact on the same, especially in surface and groundwater. To this end, it is necessary to use modern techniques and powerful, especially mass spectrometry, which in recent years has shown as a technique essential in many areas of Analytical Chemistry. This thesis has explored the potential and applications of analytical instrumentation coupling chromatography líquida-espectrometría mass in tandem (LC-MS/MS) analyzers triple cuadrupolo (QqQ) and hybrid cuadrupolo-tiempo flight (QTOF) in the determination of pesticides, mainly in the environmental field, with particular emphasis on the qualitative aspects, ie on the correct confirmation of the identity of the compounds detected along the lines of existing European guides. It has thus established a working methodology modern, highly specialized and powerful analytical tools that could be applied to other fields of interest related to the impact of pollutants on the environment, food, and ultimately on human beings alive.