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Hypersol-Macronet™ polymers have been evaluated for the adsorption of organic pollutants from aqueous solution. The adsorption performance of the polymers was compared with a commercial activated carbon, Chemviron F -400. Investigation into the physical structure of the adsorbents was performed using microscopy and the adsorption of nitrogen at liquid nitrogen temperatures. A critical analysis of the adsorption isotherm data reduction models is given. The polymers possess a bimodal pore size distribution of micropores, approximately l3A in diameter, and macropores, greater than 200A. The surface functionality of the Macronets, determined by diffuse reflectance IR, 13C NMR and X-ray photoelectron spectroscopy, is presented. Elemental analysis and direct titration techniques were also investigated. Relatively high concentrations of oxygen containing functional groups were observed on the polymers, attributed to ethers, alcohols and ketones formed during polymer production. Adsorption isotherms are given for the removal of phenol and three chlorophenols substituted in the ortho, meta and para position. The greater hydrophobicity of the chlorinated phenols resulted in stronger interaction energies and larger adsorption capacities. Batch kinetic data for the above adsorbates was modelled using the homogeneous surface diffusion correlations. Analytical techniques were developed and validated for the determination of trace levels (0.1 parts per billion) of five pesticides; atrazine, simazine, isoproturon, diuron and chlorotoluron. Single and multi-component adsorption isotherms are presented for trace concentrations of pesticides in aqueous solution. Mini-column breakthrough curves are presented for MN-200 and F-400. Selectivity of the polymers for the various pesticides was explained by differences in molecular size and the hydrophobicity of the adsorbates. The primary adsorption mechanism is hydrophobic interaction enhanced by hydrogen bonding. The negative influence of natural organic matter (NOM) on the removal of pesticides was investigated using batch and column techniques. The uptake of NOM on activated carbon is much greater than that on MN-200. Total regeneration ofMN-200 using a variety of organic solvents was achieved for high and low solid phase concentrations of pesticides. Regeneration of F-400 was ineffective. The breakthrough point of a regenerated mini-column containing MN-200 was identical to the virgin polymer data. The potential commercial application of the resin for the purification of drinking water is discussed.

Pesticide residue analysis is very important both in agriculture and environmental protection. The effectiveness of the analytical method depends very much on the extraction and preconcentration of the analytes prior to the actual analysis, as these analytes occur in trace concentrations that may be lower than the detection limit of the instrument. Various methods of extraction and pre-concentration have been introduced in an effort to decrease costs and other negative environmental impacts without compromising efficiency. One such method is single-drop micro-extraction (SDME), whose benefits cannot be overemphasised. This method has been recently introduced in the pool of pre-concentration methods for pesticide and other organic residues. In this study, the SDME method has been developed using chloroform as a solvent for preconcentration of a ten-component mixture of triazine (TP619) herbicides, followed by analysis by gas chromatography and flame ionisation detector (ppm level detection) and mass spectrometry for detection at sub-ppb level. The developed method uses the simple introduction of an air bubble to the micro-litre droplet of the organic solvent used for extraction of the triazines. This air-bubble showed the increase in the extraction efficiency of the method by about 30% relative to the optimised extraction without the air bubble. The air bubble works very well with addition of the salt (10% NaCl) to the solution being extracted, with further extraction enhancements being observed. Traditionally, the solution being extracted is stirred to achieve good mass transfer. However, the present method does not require stirring as stirring makes the system unstable resulting in reduced precision. The optimum conditions for the newly developed method, named bubble-in-drop single-drop micro-extraction (BID-SDME) were found to be as follows: 1 μL chloroform, 0.5 μL air bubble, 10% NaCl and static equilibration for 20 minutes, while the sample volume is 1 mL. This method showed linearity in the region of 1 ppm to 0.05 ppb (about six orders of magnitude) as long as the instrumental settings were optimised for increased sensitivity. The RSD values observed in this method were better than those recorded in literature, being <10%. Some instrumental manipulations are necessary to realise the full potential of the instrument. Various settings were explored on the GC-MS to optimise its performance below the ppb level. It was observed that the configuration that gave the best sensitivity and the lowest limits of detection was the high-pressure and split-less injection mode. This improved the detection limits of the instrument by 2 orders of magnitude (from 1 ppb to below 0.05 ppb). The GC-MS performance was further improved by the use of selected ion monitoring (SIM) mode of analysis. This technique reduced the interferences from the co-extracted compounds that can compromise the precision and accuracy of the analytical method especially at low concentration applicable in trace analysis. The new BID-SDME method was applied to various samples (dam water, synthetic hard water, dam sediment, humic and sandy soil samples) giving unsurpassed efficiencies with very low RSD values. In these systems, NaCl addition (10% w/v) not only increased extraction efficiency but also had a matrix-normalising effect as the RSD values were reduced and the matrix effects somewhat diminished. The application of this method to orange juice required the addition of only 5% NaCl (not 10% like the other samples). The results obtained with the extraction of orange juice were better than those recorded in literature. The normalising effect was further observed as the RSD values with addition of the NaCl were reduced the RSD from 11.7 (salt-free solution) to 5.56 (5% NaCl). These application experiments were carried out at the 0.2 ppb level using spiked samples. The method was compared against the other extraction techniques used in trace analysis (especially SPME) and it performed better overall giving lower RSD values and much improved detection limits. The calculated detection limits for the ten triazines used in the mixture were in the region of parts per trillion (0.9-14 ppt) with RSD values of < 10% with the use of internal standard. / Prof. D.B.G. Williams Mr. R. Meyer

Orientador: Hideko Yamanaka / Coorientador: Gustavo Stoppa Garbellini / Banca: Saulo Santesso Garrido / Banca: Wendel Andrade Alves / Resumo: Enzimas têm sido empregadas na construção de dispositivos para quantificação de substratos por meio de reação catalítica. Tratando-se de moléculas de alto peso molecular e estrutura complexa, tais compostos biológicos podem apresentar instabilidade, além do alto custo de produção. Neste contexto, a utilização de um peptídeo artificial, proposto por estudos de modelagem molecular para mimetizar o sítio ativo da acetilcolinesterase (AChE), foi uma alternativa investigada para o desenvolvimento de metodologia analítica para detectar pesticidas organofosforados e carbamatos, que em sua maioria apresentam mutagenicidade, elevada toxicidade e são inibidores da AChE, essencial na transmissão de impulsos nervosos. O trabalho envolveu a síntese, purificação e caracterização de duas sequências peptídicas, SEQPEP1: NH3+-EHGGPS-COO- e SEQPEP2: NH3+-CEHGGPS-COO-, obtidas por meio de metodologia em fase sólida, que apresentaram índice de pureza acima de 95 %, possibilitando aplicação analítica. À sequência peptídica SEQPEP2, foi inserido o aminoácido cisteína com a finalidade de imobilizá-lo de forma ordenada na superfície de ouro. Os estudos espectrofotométricos demonstraram uma forte interação (K = 4,10 x 105 M-1) do peptídeo com o pesticida diclorvós e a formação de um complexo com absorção máxima em λ = 250 nm. Como suporte para a imobilização do peptídeo, foram utilizados eletrodos de ouro à base de discos compactos graváveis (CD-R) (Au-CDtrodos). As condições experimentais de imobilização do peptídeo foram otimizadas sendo os melhores resultados obtidos com uma concentração de peptídeo de 1 x 10-3 mol L-1 e um tempo de incubação de 1 h à 25 ºC. A estratégia de inserir cisteína para imobilizar o peptídeo indicou recobrimento de 68 % da superfície. Demonstrou-se pelos experimentos a viabilidade... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Enzymes have been used in the construction of devices to quantify substrate by catalytic reaction. The disadvantages of biological materials as instability and high production cost are well known. Therefore, the design and development of artificial oligopeptides as a mimic of the acethylcholinesterase (AChE) binding site, preserving the highly selective biological properties, was the approach used in this study on the development of an analytical methodology for the detection of organophosphate and carbamate pesticides, because of their mutagenicity, high toxicity and the inhibition of acetylcholinesterase enzyme, which is essential for the transmission of nerve impulses. This work have involved the synthesis, purification and characterization of two peptide sequences, SEQPEP1: NH3+-EHGGPS-COO- and SEQPEP2: NH3+-CEHGGPS-COO-, obtained by solid phase methodology, which have presented a purity degree above 95 %, enabling the analytical application. A cysteine amino acid was added to the peptide sequence SEQPEP2 in order to self assembly it on the gold electrode surface. The spectrophotometric studies have demonstrated a strong interaction (K = 4.10 x 105 M-1) between the peptide and pesticide dichlorvos, and the formation of a complex with absorption maximum at λ = 250 nm. As a support for the immobilization of peptide, were used gold electrodes based on recordable compact discs (CD-R) (Au-CDtrodes). The experimental conditions for the immobilization of the peptide sequence were optimized, being the best results achieved by using a peptide concentration of 1 x 10-3 mol L-1 and an incubation time of 1 h at 25 ºC. The strategy to add a cysteine amino acid for the immobilization of the peptide has indicated a surface recovery of 68 %. The experiments have shown the viability of monitoring the interaction... (Complete abstract click electronic access below) / Mestre

Heavy metal contamination in food is a worldwide concern. Man-made ponds are domestic sites in the production of Procambarus clarkii and Procambarus zonangulus, two edible species of crayfish. Ponds may be constructed in former sugar cane or rice fields. Crayfish farming is an ancillary seasonal business within the rice-growing season. The use of products to control insects, pests, and weeds in rice and sugar cane production, may cause an accumulation of heavy metals in the crayfish tail within pond structures. Arsenic, cadmium, copper, and zinc are heavy metals that are absorbed through the roots of and distributed through rice products. Metabolites associated with rice products are absorbed in the human body. Research suggests that metabolites associated with heavy metals cause disease in animals and humans.

Thesis (Ph. D.)--University of Washington, 1983. / Vita. Bibliography: leaves [202]-216.

Graduation date: 1991

Thesis (Ph.D.) - Simon Fraser University, 2005. / Theses ( Dept. of Biological Sciences) / Simon Fraser University. Includes bibliographical references. Also issued in digital format and available on the World Wide Web.

Thesis (M.Sc.)--York University, 2008. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 56-75). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR38744

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 74-87). Available also in a digital version from Dissertation Abstracts.