Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-07-20T19:28:19Z No. of bitstreams: 1 florencepereiranovaisantunes.pdf: 2879839 bytes, checksum: 7b30047152e7859559f55c0751ebe824 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-09T13:28:00Z (GMT) No. of bitstreams: 1 florencepereiranovaisantunes.pdf: 2879839 bytes, checksum: 7b30047152e7859559f55c0751ebe824 (MD5) / Made available in DSpace on 2017-08-09T13:28:00Z (GMT). No. of bitstreams: 1 florencepereiranovaisantunes.pdf: 2879839 bytes, checksum: 7b30047152e7859559f55c0751ebe824 (MD5) Previous issue date: 2010-03-10 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O estudo da degradação de organofosforados é de suma importância tanto na área ambiental quanto na de defesa química. Tem sido descrito na literatura exaustivos estudos sobre degradação de organofosforados relacionados à agricultura. Um desses estudos leva em conta o uso da luz na degradação de um dos organofosforados mais usados na agricultura como pesticida, o paration. O processo chamado de fotocátalise heterogênea, envolve a ativação de um semicondutor (geralmente TiO2) por luz solar ou artificial. A absorção de fótons com energia superior à energia de “bandgap” resulta na promoção de um elétron da banda de valência para banda de condução com geração concomitante de um buraco (hole) na banda de valência. Estes buracos mostram potenciais suficientemente positivos, capazes de formar radicais hidroxila a partir de moléculas de água adsorvidas na superfície do semicondutor, os quais podem subseqüentemente oxidar contaminantes orgânicos. O objetivo deste trabalho foi determinar a influência da substituição de titânio por zircônio em TiO2 na adsorção de organofosforados, que é uma das etapas de degradação desses compostos. Para isso foram determinadas as estruturas, propriedades eletrônicas e vibracionais de organofosforados adsorvidos em TiO2 (101) anatase e Ti(1-x)ZrxO2. Os compostos estudados e adsorvidos são: Paration, Sarin e VX. A idéia foi propor uma técnica bem descrita experimentalmente para degradação do paration, para possível detoxificação de organofosforados usados como armas químicas, no caso, o Sarin e o VX. Foi feito o estudo da adsorção dos organofosforados em titânia substituída com zircônio na proporção Ti(1-x)ZrxO2, levando em conta que modificações na estrutura do catalisador aumentam a atividade fotocatalítica. Cálculos feitos verificam a contribuição energética da etapa de adsorção e comparando com a estrutura do catalisador puro foi possível obter melhora nesta etapa. Foram obtidas energias de fisissorção e quimissorção nas diferentes posições possíveis. O tipo de adsorção foi confirmado com estudos de diferença de carga eletrônica. Foi obtido também o estudo de frequência vibracional. A partir dos resultados, concluiu-se que a adsorção se processou de maneira mais efetiva nos casos em que foi usado o catalisador com zircônio, com energia de adsorção de -25,71kcal/mol, para o p-VX adsorvido. Em titânia pura a energia de adsorção de p-VX foi de -18,14kcal/mol. As diferenças de densidade de carga eletrônica também confirmaram os resultados. / The study of degradation of organophosphorous is critical both in the environmental area as in chemical defense. Has been described in the literature studies on degradation of organophosphorous related to agriculture. One of the study considers the use of light in a degradation of the organophosphorous pesticide used in agriculture: the parathion. The process called heterogeneous photocatalysis involves the activation of a semiconductor (usually TiO 2) by sunlight or artificial. The absorption of photons with energy higher than the energy band gap results in the promotion of an electron from the valence band to conduction band with concomitant generation of a hole (hole) in the valence band. These holes show sufficiently positive potential, capable of forming hydroxyl radicals from water molecules adsorbed on the semiconductor surface, which can subsequently oxidize organic contaminants. The aim of this study was to determine the influence of the substitution of titanium by zirconium in TiO2 adsorption of organophosphorous, which is one of the stages of degradation of these compounds. For this we determine the structures, vibrational and electronic properties of organophosphorous adsorbed on TiO2 (101) anatase and Ti(1-x)ZrxO2. The compounds adsorbed are: parathion, sarin and VX. The idea was to propose a technique well described experimentally for the degradation of parathion for possible detoxification of organophosphorous used as chemical weapons, in this case, Sarin and VX. Was done to study the adsorption of organophosphorous in titania replaced with zirconium in the ratio Ti(1-x)ZrxO2, taking into account that changes in the structure of the catalyst increase the photocatalytic activity. Calculations verify the contribution of the adsorption energy step and comparing the structure of the pure catalyst was possible to obtain improvement in this step. We obtained energies of physisorption and chemisorption at different possible positions. The type of adsorption was confirmed with studies of in electronic difference charge. Was also obtained to vibrational frequency study. From the results it was concluded that the adsorption is processed more effectively in cases where the catalyst was used with zirconium, with adsorption energy of -25.71 kcal / mol for p-VX adsorbed. Titania in pure energy of adsorption, p-VX was -18.14 kcal / mol. The difference in electronic charge density also confirmed the results.

Detection of organic molecules present on the surface of dust particles is important in homeland security, agriculture, and several other applications. The research presented reports the ability of the aerosol mass spectrometer (AMS) to detect molecules on the surface of dust particles without detecting the particle core. Experiments were carried out to detect semi-volatile organic compounds adsorbed onto the surface of particulates without interference from the dust particle core. Methyl salicylate, oleic acid, and organophosphorus pesticides such as Malathion were detected on the surface of particles representative of dust-type materials. Zeolite powders were used as aerosol support, representative of a typical silica mineral aerosol present in the atmosphere. Mass spectral fingerprint information was gained by first directly detecting atomized species to record their clean electron impact mass spectrum. This facilitated detection during later experiments of organic molecules coated on an inorganic support. Spectra obtained give mass spectrometric signatures of molecules coated on inorganic particles without detection of the particle core. An important feature of the AMS is the ability to equate an ion rate detected in the mass spectrometer to a mass concentration of a given chemical species in a sample using its ionization efficiency. Based on an average inlet flow rate of 1.2 cm 3sec -1 the ionization efficiencies obtained were 5.89x10-5, 1.15x10-6, and 1.62x10-5 for Malathion, methyl salicylate, and oleic acid, respectively. These experiments and the results obtained show that detection and characterization of organic species adsorbed onto inorganic dust particles are possible at µg m-3 concentrations using the AMS.

De nouvelles méthodes de détection et de quantification du VX (O-éthyl S–(2(diisopropylamino)éthyl) (méthylphosphonothioate)) dans le plasma par chromatographie liquide couplée à un spectromètre de masse en tandem (LC-MS/MS) ont été développées. Après avoir été mise en œuvre en milieu HBSS (rendement > 99%), la méthode d'extraction liquide-liquide de notre composé d'intérêt nous permet d'obtenir en milieu plasmatique un rendement de soixante-cinq pour cent (65%). Cette méthode d'extraction permet d'évaluer la présence de VX dans de très faibles volumes d'échantillons de plasma (entre 20 et 1000 µL), donc dans des volumes compatibles avec des expérimentations sur de petits rongeurs. Cette extraction est suivie d'une analyse par LC-MS/MS en phase 100% organique. Des limites de détection de 0,15 et 0,5 pg/mL (pour 5 µL injecté) sont obtenues respectivement avec l'utilisation de la colonne Allure Biphényl (Restek) et Lux Cellulose-1 (Phenomenex). Afin d'étudier la toxicocinétique des énantiomères du VX dans le plasma, nos recherches se sont ensuite focalisées sur la séparation de ces derniers. Des résultats prometteurs ont été obtenus en utilisant une colonne Lux cellulose-2 (Phenomenex). / Innovative analytical methods have been developed to detect and quantify the organophosphorus nerve agent, VX (O-ethyl S–(2(diisopropylamino)ethyl) (methylphosphonothioate)), in plasma using liquid chromatography coupled with mass spectrometry (LC-MS/MS) technique. Liquid-liquid extraction of VX from HBSS environment was achieved with excellent yields (> 99%). Next, extraction from plasma was performed and generated a recovery rate of approximately sixty-five percent (65%). Our distinctive extraction methodology was implemented to evaluate the presence of VX in very small quantities of plasma (between 20 to 1000 µL) as in small rodents' experiments. It was followed by an LC-MS/MS analysis in a 100% organic phase. A Lux Cellulose-1 column (Phenomenex) and an Allure biphenyl column (Restek) were tested with detection limit at 0.15 pg/mL and 0.5 pg/mL in plasma (5 µL injected), respectively. Finally, our study was focused on the separation of VX enantiomers and hopeful results were provided using a Lux cellulose-2 column (Phenomenex).

In our earlier work, silica-based diatom frustules were successfully converted to 3-dimesional F-doped titania-based replicas via shape-preserving gas/solid displacement reactions, and experiments showed that the hydrolysis of organophosphorous ester pesticides, methyl paraoxon (MOX) and methyl parathion (MTH) was significantly faster in the presence of these 3-D titania nanostructures than in the presence of other commercial titania nanoparticles. The enhancement effect of titania frustules appeared to be strongly related to the amount of F-doping on these materials. In this work, a wider range of titania frustule replicas with various F-doping were prepared and characterized, and compared in the hydrolysis of MOX and MTH as well as three carboxylic acids (methyl salicylate, methyl benzoate and methyl 4-(aminomethyl)benzoate). A strong relationship between the amount of F-doping and the enhancement effect on the hydrolysis of organophosphorous esters was still observed. However, such enhancement effect did not occur in the hydrolysis of the carboxylic acids. It was discovered that fluorine-leaching from the titania frustules was significant and yielded high concentration of fluoride ions in the reaction solutions. Dissolved fluoride ions alone could significantly catalyze the hydrolysis of organophosphorous esters but not that of carboxylic acids in the oxide-free systems. It is believed that fluoride ions act as nucleophilic catalysts to accelerate the hydrolysis of organophosphorous esters. Comparison in the hydrolysis product formation from the two potential hydrolysis pathways (i.e., the P-O bond and the C-O bond cleavages) in the studied systems also supports the direct involvement of dissolved fluoride ions in the observed catalytic effect.

Made available in DSpace on 2016-06-02T19:32:07Z (GMT). No. of bitstreams: 1 5397.pdf: 2672237 bytes, checksum: 66d95a1c81d09e4aa7e3b8016ac5b2dc (MD5) Previous issue date: 2013-07-29 / Universidade Federal de Sao Carlos / Pesticides are potentially toxic compounds to humans and other living beings, which are indispensable for pests removal in agriculture worldwide. The result of their overuse is the inevitable contamination of aquatic and terrestrial ecosystems. The need for degradation of these compounds has been subject of several studies. The enzymatic biodegradation of synthetic pesticides by microorganisms is an important strategy for removing these pollutants from the environment. Marine fungi are an excellent source of highly oxygenated bioactive compounds with huge potential to biotransform xenobiotics such as pesticides. Thus, the objective of this project was to study the biotransformation of the organophosphate pesticide methyl parathion using fungi of marine origin isolated from the ascidian Didemnum ligulum. Initially, 17 fungi strains have undergone screening on agar culture medium containing different pesticide concentrations (120 mg/L, 240 mg/L and 360 mg/L), and the three strains that showed the greatest growth diameter of the colony, were subjected to culture in a liquid medium to quantify the possible degradation of the methyl parathion. For these strains, the eficiency of degradation was monitored by high performance liquid chromatography (HPLC). Methyl parathion was almost completely degraded in 20 days, but there was no significant difference between the reactions with the fungi strains and the abiotic control. The microorganisms, however, showed ability to metabolize p-nitrophenol, the main degradation product of methyl parathion. In conclusion, these three marine fungi, identified as two strains of Penicillium citrinum and one strain of Fusarium proliferatum, have proven to be important sources to study xenobiotic biotransformation. / Os pesticidas são compostos, potencialmente tóxicos ao homem e demais seres vivos, que hoje são indispensáveis na remoção de pragas na agricultura mundial. O resultado do seu uso excessivo é a inevitável contaminação dos ecossistemas aquáticos e terrestres. A necessidade da degradação destes compostos tem sido fonte de diversos estudos. A biodegradação enzimática de pesticidas sintéticos por micro-organismos representa uma importante estratégia para a remoção desses poluentes do meio ambiente. Uma excelente fonte de compostos bioativos altamente oxigenados, com enorme potencial bioenzimático a ser explorado na biotransformação de xenobióticos, como os pesticidas, são os fungos marinhos. Sendo assim, o objetivo deste projeto foi estudar a biotransformação do pesticida organofosforado metil paration utilizando-se de fungos de origem marinha isolados da ascídia Didemnum ligulum. Inicialmente, 17 linhagens de fungos passaram por uma triagem em meio de cultura sólido contendo diferentes concentrações (120 mg/L, 240 mg/L e 360 mg/L) de pesticida, e as que apresentaram o melhor desenvolvimento nesse meio, de acordo com observação por diâmetro de crescimento da colônia, foram submetidas a um cultivo em meio líquido para quantificar a possível degradação do metil paration. Três linhagens foram selecionadas para essa segunda etapa, na qual a eficiência de degradação foi monitorada por cromatografia líquida de alta eficiência (CLAE). O metil paration foi completamente degradado em 20 dias, porém não houve significativa diferença entre as reações com as linhagens de fungos e o controle abiótico. Os micro-organismos, no entanto, se mostraram capazes de metabolizar o p-nitrofenol, principal produto de degradação do pesticida metil paration. Assim, esses três fungos marinhos, identificados como duas linhagens de Penicillium citrinum e uma de Fusarium proliferatum, demonstraram ser importantes fontes para estudos de biotransformação de xenobióticos.

L'objectif de ce travail de thèse est la modification de surface de deux supports inorganiques (nanoparticules mésoporeuses de silice, nanoparticules de carbonate de calcium) par greffage molécules organiques (organosilanes et phosphonates).Des nanoparticules mésoporeuses de silice (MSN) de type MCM-41 ont été synthétisées par micro-émulsion directe et greffées dans des conditions douces par l'isocyanatopropyle trichlorosilane. Ensuite, la réactivité de la fonction isocyanate a été testée par post-modification en utilisant plusieurs nucléophiles aminés. La synthèse, le greffage et la post-modification ont été caractérisés par plusieurs méthodes physico-chimiques. Des MSN fonctionnalisées en surface par un agent de couplage photolabile ont également été élaborées et testées sous irradiation UV, dans la perspective de préparer des nanovalves pour la délivrance photo-contrôlée de médicaments.La modification de surface de nanoparticules de carbonate de calcium (calcite) par formation de monocouches phosphonates a été étudiée. Les conditions réactionnelles ont été optimisées pour favoriser le greffage en évitant la dissolution du carbonate de calcium et la précipitation de phases de phosphonate de calcium. Des monocouches denses ont été obtenues avec différents acides phosphoniques en milieu organique et en milieu aqueux. L'utilisation d'esters phosphoniques (diéthyl esters) a également été explorée. Les nanoparticules modifiées ont été caractérisées par différentes techniques (spectroscopies RMN et IR, DRX, analyse élémentaire, microscopie électronique, test de mouillabilité) afin d'identifier la nature des espèces de surface. / The objective of this thesis is the surface modification of two inorganic supports (mesoporous silica nanoparticles, calcium carbonate) by grafting organic molecules (organosilanes and phosphonates derivatives).Mesoporous silica nanoparticles (MSN) of MCM-41 type were synthesized by direct micro-emulsion and grafted under mild conditions using isocyanatopropyltrichlorosilane. Then, the reactivity of the isocyanate function was tested by post-modification using several amino nucleophiles. Synthesis, grafting and post-modification steps have been characterized by several physicochemical methods. MSN surface functionalized with a photolabile coupling agent have also been developed and tested under UV irradiation, with a view to prepare nanovalves for photo-controlled drug-delivery.The surface modification of nanoparticles of calcium carbonate (calcite) by phosphonate monolayers was investigated. The reaction conditions were optimized to favor grafting and prevent the dissolution of calcium carbonate leading to the precipitation of calcium phosphonate phases. Dense monolayers were obtained with different phosphonic acids in organic and aqueous media. The use of phosphonic esters (diethyl esters) was also explored. The modified nanoparticles were characterized by different techniques (NMR and IR spectroscopy, XRD, elemental analysis, electron microscopy, wettability testing) to identify the nature of the surface species.

Le traitement des effluents aqueux issus des usines de retraitement de La Hague est un enjeu important pour l'environnement. Ces effluents sont contaminés par des substances organiques et des éléments possédant une radioactivité résiduelle. Ce travail porte donc sur le développement et l'optimisation du procédé de dépollution avec pour objectifs d'exempter l'effluent de toute pollution et de former un déchet final compatible avec les matrices de conditionnement classiques dans le milieu nucléaire. Le procédé de séparation se décompose en deux étapes : l'étape de solubilisation de la pollution dans des micelles de tensioactifs et l'étape de précipitation d'une phase minérale par transition sol-gel.Dans la cadre de la thèse, seule la pollution due aux radionucléides a été étudiée. Lors de la première étape, la stratégie a consisté à utiliser des molécules complexantes capable d'interagir avec les ions et de former des complexes préférentiellement solubles dans le cœur des micelles de tensioactifs. Par la suite, la deuxième étape a consisté à ajouter un précurseur de silice qui après hydrolyse et polycondensation permet d'agréger les micelles contenant les complexes entre elles et de former une phase silice qui précipite de façon in-situ. L'objectif de dépollution de l'effluent a été atteint et le déchet final formé est une poudre de silice contenant les micelles et la pollution qui après calcination est compatible avec les matrices de conditionnement telles que le verre ou le ciment. Différentes études ont permis de définir un système de référence pour lequel le procédé de séparation est optimal. Ce système comprend un tensioactif non-ionique (P123), un ion simulant les radionucléides (néodyme), une molécule complexante (HDEHP) et un précurseur de silice (TEOS). Ainsi, ce système a fait l'objet d'études approfondies pour élargir le champ d'action du procédé de séparation et pour comprendre les mécanismes en jeu lors de la complexation des ions et de la solubilisation micellaire, puis lors de la formation de la poudre de silice avec des techniques de diffusion, d'imagerie, de spectrométrie et d'analyses de surface.En conclusion, le procédé alternatif de dépollution développé dans cette thèse a permis d'atteindre les objectifs de dépollution et d'expliquer les différents mécanismes qui régissent chaque étape du procédé.Mots-clés : Tensioactifs, Lanthanides, Ligands organophosphorés, Procédé sol-gel, Diffusion des neutrons, wet-STEM / Treatment of aqueous outflows by complexation in micellar media and precipitation with sol-gel processAbstract Being able to deal with aqueous outflows from treatment sites in the Hague is a major environmental issue. These outflows are contaminated with organic substances and elements with residual radioactivity.This work deals with the development and optimization of the process of depolluting, and we aim at removing all pollution from the outflow, and produce a final waste compatible with traditional conditioning matrices in the nuclear area. The separation process consists of two steps: dissolving the pollution in the surfactants micelles, and precipitating a mineral phase via sol-gel transition. Within this thesis, only pollution originating from radionuclides is studied. During the first step, our strategy is to use complexing molecules able to interact with ions and to form mainly solvable complexes at the core of surfactant micelles. Thereafter, the second step consisted to add silica precursor which, after hydrolyse and polycondensation, makes it possible to aggregate those micelles that contain complexes together, and to form a silica phase which precipitates in an in-situ fashion.The goal to depollute the outflow was achieved, and the final waste thus produced is a silica powder that contains the micelles and the pollution which, after calcination, is compatible with conditioning matrices such as glass or concrete. A reference system for which the separation process is optimal was defined throughout various studies. This system contains a non-ionic surfactant (P123), an ion that surrogates radionucleides (neodymium), a complexing agent (HDEHP) and a silica precursor (TEOS). Hence, this system was further studied in order to broaden the application scope of the separation process, as well as to understand the mechanisms involved, during the complexation of the ions and the micellar solubilization and during the formation of the silica powder. This study was performed using diffusion, imaging and spectrometry techniques.To conclude, the alternative depolluting process developed as part of this thesis allowed to achieve the depolluting goals and to explain the different mechanisms that govern each step of the process.Keywords: Surfactants, Lanthanides, Organophosphorous ligands, Sol-gel process, Neutrons scattering, wet-STEM

Os objetivos do presente trabalho foram avaliar a ocorrência / persistência / degradação de resíduos do inseticida organofosforado pirimifós-metil em grãos de trigo, milho e milho pipoca e em alguns de seus produtos processados, bem como a ação residual desse inseticida sobre Sitophilus spp. (Coleoptera, Curculionidae). O tratamento dos grãos foi realizado de modo a se obter a concentração teórica de 12 mg.kg-1 (ppm) de pirimifós-metil, tendo sido aplicados o equivalente a 5 litros de solução por tonelada de grãos. As amostras para estudos de resíduos foram tomadas aos zero, 15, 30, 60, 120 e 240 dias após o tratamento. O método analítico consta da extração dos resíduos com acetona, limpeza com partição acetonitrila/hexano seguida de coluna cromatográfica de sílica eluída com mistura de hexano+acetona (9/1, v/v). A determinação quantitativa foi feita por técnica de cromatografia em fase gasosa, usando-se cromatógrafo equipado com detector fotométrico de chama (GLC/FPD). Foram analisadas 264 amostras no total, sendo 72 de grãos cereais e 192 de seus produtos processados. Para os estudos de ação residual do inseticida sobre adultos de Sitophilus spp. os insetos foram submetidos a testes em exposição aos grãos tratados após 15 dias decorridos do tratamento, 30 dias após, e, subseqüentemente, em intervalos mensais até 12 meses. Os limites de quantificação dos resíduos pelo método de análise, para os diferentes substratos variaram de 0,05 a 0,1 mg.kg-1. Os resíduos de pirimifós-metil não foram persistentes nos grãos nem em seus produtos processados, decrescendo de 4-8 vezes no período de amostragem. Eles foram maiores nos produtos processados ricos em óleos (farelo de trigo e de milho), menores nos grãos (estes semelhantes às farinhas integral e branca, e pipoca) e, ainda menores, no pão, farinha de milho e canjica. O inseticida pirimifós-metil mostrou-se bastante eficiente no controle de Sitophilus spp., no tratamento dos três tipos de grãos cereais durante todo o período de observação. / The purposes of this study were to evaluate the occurence, persistence and degradation of pyrimiphos-methyl organophosphorus insecticide residues on wheat, corn and popcorn grains in and some of their processed products, as well the residual action of this insecticide for the control the Sitophilus spp. (Coleoptera, Curculionidae). Grain treatment was performed to obtain the theoretic concentration of 12 mg.Kg-1 (ppm) of pyrimiphos-methyl, which was applied at the dosage of 5 L of solution/ton of the grain. Sampling was performed at 0, 15, 30, 60, 120 and 240 days after the treatment. The samples were analyzed for residues of pyrimiphos-methyl using a residue method based on extraction with acetone, clean up by partition with acetonitrile/hexane followed by silica gel column chromatography eluted with a mixture of hexane + acetone (9:1) (v:v) solution. Residue determinations were done by the gas chromatography technique using a flame photometry detector (GLC/FPD). Total samples analyzed were 264, being 72 of cereal grains and 192 of processed products. The studies of residual action of the insecticide for the control of Sitophilus spp adults were conducted with adults and exposing the insects to treated grains 15 days after the application, 30 days, and subsequently at monthly intervals up to 12 months. The limits of quantitation of the analytical method for different substracts ranged between 0.05 to 0.1 mg.kg-1 (ppm). Pyrimiphos-methyl residues were not persistent on the grains and processed products. A decay of 4 to 8 times during the sampling period was observed. The residues found were higher in the processed products with high oil content (wheat and corn brans), lower on grains (similar to whole and white flours and popcorn) and even lower in bread, corn flour and "canjica". Pyrimiphos-methyl was very efficient for the control of Sitophilus spp on the three grain types during the entire period of observation.

Os objetivos do presente trabalho foram avaliar a ocorrência / persistência / degradação de resíduos do inseticida organofosforado pirimifós-metil em grãos de trigo, milho e milho pipoca e em alguns de seus produtos processados, bem como a ação residual desse inseticida sobre Sitophilus spp. (Coleoptera, Curculionidae). O tratamento dos grãos foi realizado de modo a se obter a concentração teórica de 12 mg.kg-1 (ppm) de pirimifós-metil, tendo sido aplicados o equivalente a 5 litros de solução por tonelada de grãos. As amostras para estudos de resíduos foram tomadas aos zero, 15, 30, 60, 120 e 240 dias após o tratamento. O método analítico consta da extração dos resíduos com acetona, limpeza com partição acetonitrila/hexano seguida de coluna cromatográfica de sílica eluída com mistura de hexano+acetona (9/1, v/v). A determinação quantitativa foi feita por técnica de cromatografia em fase gasosa, usando-se cromatógrafo equipado com detector fotométrico de chama (GLC/FPD). Foram analisadas 264 amostras no total, sendo 72 de grãos cereais e 192 de seus produtos processados. Para os estudos de ação residual do inseticida sobre adultos de Sitophilus spp. os insetos foram submetidos a testes em exposição aos grãos tratados após 15 dias decorridos do tratamento, 30 dias após, e, subseqüentemente, em intervalos mensais até 12 meses. Os limites de quantificação dos resíduos pelo método de análise, para os diferentes substratos variaram de 0,05 a 0,1 mg.kg-1. Os resíduos de pirimifós-metil não foram persistentes nos grãos nem em seus produtos processados, decrescendo de 4-8 vezes no período de amostragem. Eles foram maiores nos produtos processados ricos em óleos (farelo de trigo e de milho), menores nos grãos (estes semelhantes às farinhas integral e branca, e pipoca) e, ainda menores, no pão, farinha de milho e canjica. O inseticida pirimifós-metil mostrou-se bastante eficiente no controle de Sitophilus spp., no tratamento dos três tipos de grãos cereais durante todo o período de observação. / The purposes of this study were to evaluate the occurence, persistence and degradation of pyrimiphos-methyl organophosphorus insecticide residues on wheat, corn and popcorn grains in and some of their processed products, as well the residual action of this insecticide for the control the Sitophilus spp. (Coleoptera, Curculionidae). Grain treatment was performed to obtain the theoretic concentration of 12 mg.Kg-1 (ppm) of pyrimiphos-methyl, which was applied at the dosage of 5 L of solution/ton of the grain. Sampling was performed at 0, 15, 30, 60, 120 and 240 days after the treatment. The samples were analyzed for residues of pyrimiphos-methyl using a residue method based on extraction with acetone, clean up by partition with acetonitrile/hexane followed by silica gel column chromatography eluted with a mixture of hexane + acetone (9:1) (v:v) solution. Residue determinations were done by the gas chromatography technique using a flame photometry detector (GLC/FPD). Total samples analyzed were 264, being 72 of cereal grains and 192 of processed products. The studies of residual action of the insecticide for the control of Sitophilus spp adults were conducted with adults and exposing the insects to treated grains 15 days after the application, 30 days, and subsequently at monthly intervals up to 12 months. The limits of quantitation of the analytical method for different substracts ranged between 0.05 to 0.1 mg.kg-1 (ppm). Pyrimiphos-methyl residues were not persistent on the grains and processed products. A decay of 4 to 8 times during the sampling period was observed. The residues found were higher in the processed products with high oil content (wheat and corn brans), lower on grains (similar to whole and white flours and popcorn) and even lower in bread, corn flour and "canjica". Pyrimiphos-methyl was very efficient for the control of Sitophilus spp on the three grain types during the entire period of observation.

Metallohydrolases with dinuclear-zinc active sites perform many important biological hydrolytic reactions on a variety of substrates. In this regard, metallo-β-lactamases (mβ1, class B) represent a unique subset of zine hydrolases that hydrolyze the β-lactam ring in several antibiotics. The antibiotic resistance that results from this hydrolysis is becoming an increased threat for the clinical community. These metalloenzymes can hydrolyze a wide range of β-lactam substrates, such as cephamycins and imipenem that are generally resistant t the serine-containing β-lactamases. Therefore, the clinical application of the entire range of antibiotics is severely compromised in bacteria that produce mβls. Due to the lack of information on the mechanism of mβls, to-date, no clinically known inhibitors is there for mβls. In this present study, we synthesized several mono and dizinc complexes as models for the mβls and investigated the differences in their hydrolytic properties. This study supports the assumption that the second zinc in the dinuclear enzymes does not directly involve in the catalysis, but may orient the substrates for hydrolysis and the basic amino acid residues such as Asp and His may activate the zinc-bound water molecules, fulfilling the role of the second zinc in the mononuclear enzymes. The effect of various side chains on the hydrolysis of some commonly used cephalosporin antibiotics by mβl from B.cereus is described. It is shown that the cephalosporins having heterocyclic thiol side chains are more resistance to mβl-mediated hydrolysis than the antibiotics that do not have such side chains. This is partly due to the inhibition of enzyme activity by the thiol moieties eliminated during the hydrolysis. It is also observed that the heterocyclic side chains in pure form inhibit the lactamase activity of mβl as well as its synthetic mimics. The mode of binding of these heterocyclic side chains to the zinc has been analyzed from the crystal structure of the tetranuclear zinc complexes. The theoretical studies suggest that the eliminated heterocyclic thiols undergo a rapid tautomerism to produce the corresponding thiones. These thiones are found to irreversibly inhibit the LPO-catalyzed iodination reaction. The reaction of various thiones with I2 leads to the formation of thione-iodine complexes similar to that of the most commonly used antithyroid drug methimazole(MMI). These observations suggest that some of the latest generation of antibiotics may show negative effects on thyroid gland upon hydrolysis. Synthetic organophosphorus compounds have been used extensively as pesticides and petroleum additives. These compounds are very toxic to mammals and their widespread use in agriculture leads to serious environmental problems. Therfore, degradation of organophosphorus trimesters and remediation of associated contaminated sites are of worldwide concern. In this regards, the bacterial phsophotriesterase (PTE) enzyme plays an important role in degrading a wide range of organophosphorus esters and the active side of PTE has been shown to be very similar to that of mβl. This identification prompted us to check the hydrolysis of phosphotriesters by the mβl and its mimics. It has been observed that the dinuclear zine(II) complexes that do not allow a strong binding of phosphodiestes would be a better PTE mimics.