O presente trabalho enfoca o desenvolvimento de procedimentos analíticos limpos através da extração e pré-concentração de íons metálicos em ponto nuvem para aumento de sensibilidade, melhoria de seletividade e substituição de solventes tóxicos. Cobre(II), ferro(II) e níquel(II) foram extraídos simultaneamente em digeridos de materiais vegetais, utilizando como agente extrator o Triton X-114, após formarem complexos hidrofóbicos com o 1,2-tiazolilazo-2-naftol (TAN). Os analitos foram determinados por espectrometria de absorção atômica com chama (Cu, Fe e Ni) ou por espectrofotometria de absorção molecular (Fe). A determinação de Cu e Ni por espectrofotometria de absorção molecular foi inviabilizada por interferências espectrais causadas pela formação de complexos com diversos íons metálicos encontrados nos digeridos dos materiais vegetais. Nas medidas por FAAS, os limites de detecção (99,7 % de confiança) foram estimados em 1,10 e 5 µg L-1 para cobre, ferro e níquel, respectivamente. Respostas lineares foram observadas para cobre e ferro na faixa de concentração de 25-200 µg L-1 e para o níquel entre 5 e 80 µg L-1 . O fator de enriquecimento foi estimado em 30 e a extração dos analitos foi quantitativa, de acordo com medidas efetuadas no sobrenadante após extração. Na determinação de ferro por espectrofotometria de absorção molecular, o limite de detecção foi estimado em 1 µg L-1 , com resposta linear entre 6 e 60 µg L-1 e fator de enriquecimento estimado em 20. Após digestão com ácidos diluídos em forno de microondas, o procedimento proposto foi aplicado à determinação dos analitos em digeridos de materiais de referência certificados, sendo os resultados concordantes com os valores certificados a nível de confiança de 95 %. O consumo de reagentes foi estimado em 50 mg Triton X-114 e 150 µg TAN por determinação. / This work is focused on the development of green analytical procedures for cloud-point extraction and concentration of metal ions, aiming increasing sensitivity, improving selectivity and avoiding the use of toxic solvents. Copper(II), iron(II) and nickel(II) were simultaneously extracted from plant materials digests, by using Triton X-114 as extracting agent, after formation of hydrophobic complexes with 1,2- tiazolylazo-2-naphthol (TAN). The analytes were determined by flame atomic absorption spectrometry (Cu, Fe and Ni) or by molecular absorption spectrophotometry (Fe). The determination of Cu and Ni by UV-vis spectrophotometry was hindered by spectral interferences caused by the formation of complexes with several metal ions in the sample digests. In the measurements by FAAS, the detection limits (99.7 % confidence level) were estimated as 1, 10 and 5 µg L-1 for copper, iron and nickel, respectively. Linear responses were observed in the 25-200 µg L-1 range for copper and iron and 5-80 µg L-1 for nickel. The enrichment factor was estimated as 30 and the extraction was quantitative, as evaluated by measurements in the supernatant solution after extraction. For iron determination by UV-vis spectrophotometry, the detection limit was estimated as 1 µg L-1 , with linear response within 6 and 60 µg L-1 and enrichment factor of 20. After digestion with diluted acids in microwave oven, the procedure was applied to the determination of the metals in reference materials and the results agreed with the certified values at the 95 % confidence level. The reagent consumption was estimated as 50 mg Triton X-114 and 150 µg TAN per determination.

No description available.

Reflexo de um modo de vida que exige locomoção rápida e com um mínimo de conforto, atualmente, nas grandes metrópoles, há um grande número de veículos em circulação que emitem gases poluentes (hidrocarbonetos, CO e óxidos de nitrogênio - NOx). Para minimizar a emissão desses gases, os carros atuais são dotados de conversores catalíticos, formados pelos metais do grupo da platina, com a finalidade de converter gases nocivos em gases menos agressivos ao ambiente e ao homem. Porém, esses elementos constituintes dos conversores catalíticos podem ser expelidos para o ambiente, na forma de materiais particulados em suspensão, por volatilização ou junto com os gases da combustão. Desta forma, esses elementos podem acumular-se nos mais diversos ambientes. A utilização de amostras biológicas, tal como sangue, na investigação e no controle à exposição de elementos nos seres humanos vem sendo praticada há muito tempo. Estudos com materiais biológicos apontam que as concentrações de metais do grupo da Platina estão na ordem de ng/kg. Tais níveis de concentração representam um grande desafio para a Química Analítica, pois são muito baixos para que se tenham resultados com boa precisão e exatidão nas análises, mesmo utilizando técnicas muito sensíveis. Como alternativa para contornar os problemas, nas determinações destas baixas concentrações, etapas prévias de pré-concentração, com posterior determinação, vem sendo propostas com sucesso. Nessa pesquisa, para a pré-concentração dos analito, extração em ponto nuvem foi empregada com determinação por espectrometria de absorção atômica por forno de grafite. O procedimento da extração em ponto nuvem consiste em derivatizar os analitos em espécies hidrofóbicas por meio de um agente complexante, e extrair por micelas formadas a partir de um surfactante não iônico, induzidas por mudança de temperatura. Essa extração se baseia no fenômeno que ocorre com a formação de agregados micelares, quais apresentam caráter hidrofóbico. Foram estudados diferentes ligantes, e o melhor resultado para a extração foi obtido empregando-se o APDC (pirrolidina ditiocarbamato de amônio). Os parâmetros da extração em ponto nuvem otimizados para o melhor ligante foram: pH=7; 3,0x10-2 mol L-1 de APDC; 0,5 % m v-1 de Triton X-114; 60ºC durante 10 min de banho, 10 min de centrifugação e 50 mg L-1 Cu(II) como modificador químico. O método apresentou fator de enriquecimento de 24 vezes, mas o LOD (0,24 µg L-1) ficou muito acima dos valores apresentados em amostras de indivíduos expostos e não expostos. Adições de 1, 5 e 10 µg L-1 foram realizadas para avaliar a exatidão do método e apresentaram recuperações média de 91%. / Reflecting a way of life that requires fast displacement with a minimum of comfort, currently in big cities, there are a large number of vehicles that produce a large amount of waste gases (hydrocarbons, CO and nitrogen oxides - NOx) to atmosphere. To minimize the emission of these gases, current cars are equipped with catalytic converter, made of platinum group metals, which has the purpose of converting the noxious gases into less harmful gases to environment and man. However, these constituents of the catalytic converter can be expelled to the environment in form of particulates in suspension, or by volatilization along with the combustion gases. Thus, these elements can accumulate. Biological samples such as blood, urine, hair, nail, have been used for a long time in studies and control of human exposition to elements. Studies of biological materials indicate that the concentrations of platinum group metals are the order of ng/kg. Such concentration levels means a huge challenge for analytical chemistry, as they are too low to provide the necessary results with good precision and accuracy in the analysis, even using very sensitive techniques. As an alternative to overcome the problems in the provisions of these low concentrations, preconcentration methods, with subsequent determination has been proposed successfully. Cloud point extraction (CPE) was proposed in this work for pre-concentration of the analytes. CPE procedure consists in derivatizing the analytes into hydrophobic species by a complexing agent and extracts them trapped inside micelles formed from a nonionic surfactant, induced by temperature change. The cloud point extraction is based on the phenomenon that occurs with the formation of these hydrophobics aggregates by those micelles. Dithizone, DBTC, DMG, DDTC and APDC ligands were studied. The optimized parameters of cloud point extraction were: pH=7; 3,0x10-2 mol L-1 APDC; 0,5% m v-1 Triton X-114; 60 ºC while 10 min of termal bath and 10 min of centrifugation time. A Cu (II) 50 mg L-1 solution was used as a chemical modifier. The method was evaluated after optimized cloud point extraction\'s parameters conditions. It showed enrichment factor of 24-fold, but the limit of detection (0.24 µg L-1) was higher than the values expected to samples of exposed and non exposed individuals. A recovery test was done and a satisfactory recovery result was provided, up to 91%.

Submitted by Eunice Novais (enovais@uepg.br) on 2018-04-24T17:27:14Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Jucimara Kulek de Andrade.pdf: 4583083 bytes, checksum: 9a03d4f30fb1122bb87feac6d618d7a1 (MD5) / Made available in DSpace on 2018-04-24T17:27:14Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Jucimara Kulek de Andrade.pdf: 4583083 bytes, checksum: 9a03d4f30fb1122bb87feac6d618d7a1 (MD5) Previous issue date: 2018-02-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O antimônio e o cromo são elementos presentes no ambiente de forma natural ou decorrente de atividades antrópicas. O comportamento, biodisponibilidade, toxicidade e transporte desses elementos são dependente das suas formas específicas, ou seja, sua especiação. Assim, é importante conhecer as diferentes espécies do elemento em um meio específico. O presente trabalho teve por objetivo implantar e validar em laboratório protocolos analíticos para o estudo da especiação de Sb e Cr em amostras de água mineral e natural, empregando técnicas de extração com detecção por espectrometria atômica. A especiação de Sb por extração por ponto nuvem envolveu a extração seletiva de Sb(III) em pH 2, com pirrolidina ditiocarbamato de amônio – APDC (complexante) em meio de surfactante (Triton X-114). A determinação do teor total de Sb foi realizada pelo mesmo procedimento, após redução do Sb(V) para Sb(III) usando L-cisteína. Um amplo estudo da presença de Sb(III) e Sb(V) em amostras brasileiras de água mineral envasadas em PET foi realizado. A concentração média de Sb(total) para 39 amostras recentemente envasadas foi de 4 ± 1,4 μg L-1, sendo que 70% das amostras estão dentro dos limites aceitáveis pela ANVISA (5,0 μg L-1). A espécie majoritária nas amostras foi o Sb(III) com 53 a 79% do teor total de Sb, sugerindo a migração do Sb2O3 do PET para a bebida. Um estudo foi conduzido com cinco marcas de água mineral envasada e analisadas durante seis meses. O teor de Sb(total) na água mineral aumentou de 2 a 27% após 6 meses de estocagem. Esses resultados indicam que ocorre a migração do Sb presente no PET para a bebida engarrafada. A migração do Sb do PET para água mineral foi avaliada sob diferentes condições de armazenamento (tempo, temperatura, exposição solar) usando a própria bebida como simulante e com simulantes alimentícios (água ultrapura e solução ácida). Nesses ensaios, observou-se um aumento de até 214% do teor de Sb quando a temperatura de armazenamento aumentou até 80ºC. Um aumento de 323% foi observado quando as amostras foram expostas por 7 dias à radiação solar e de até 600% com simulante ácido acético por 10 dias. Com relação à distribuição das espécies, a espécie que apresentou aumento mais significativo foi de Sb(III). A especiação de Cr por emulsificação assistida por ultrassom envolveu a extração seletiva do Cr(VI) e pré-concentração com tributilfosfato (TBP) (solvente extrator orgânico), em meio de HCl e NaCl. A dispersão da solução extratora foi realizada com banho ultrassônico em substituição a um solvente dispersor. A determinação do teor total de Cr(III) foi realizada pelo mesmo procedimento, após oxidação do Cr(III) para Cr(VI) usando KMnO4. Um estudo de especiação de Cr em amostras de água natural do Oeste, Centro-Oeste e Campos Gerais do Estado do Paraná, Brasil foi realizado. As concentrações totais de Cr foram inferiores a 1,0 μg L-1, portanto, compatíveis com águas não contaminadas. O Cr dissolvido foi a maior fração para as amostras, indicando que o Cr pode ter uma maior capacidade de mobilidade e possível biodisponibilidade nessas águas. Com relação a distribuição do Cr na fração dissolvida, a fração majoritária foi de Cr(VI). Esta é a espécie mais tóxica e forma mais esperada em águas naturais oxigenadas. A variabilidade nos resultados mostra a necessidade de monitoramento das concentrações totais desses elementos e sua especiação, nos ambientes aquáticos e águas engarrafadas, como forma avaliar sua toxicidade e garantir a segurança social e ambiental. / Antimony and chromium are elements present in the environment naturally or due to anthropic activities. The behavior, bioavailability, toxicity and transport of these elements are dependent on their specific forms, i.e., their speciation. Thus, it is important to know the different species of this element in a specific medium. Thereby, this work proposes to implement and validate in laboratory analytical protocols for the study of Sb and Cr speciation in mineral and natural water, employing extraction technique with detection by atomic absorption. The Sb speciation by cloud point extraction involved the selective extraction of Sb(III) at pH 2, with ammonium pyrrolidinedithiocarbamate - APDC (complexing agent) in surfactant medium (Triton X-114). By the same procedure was performed the determination of the total Sb content, however after reduction of Sb (V) to Sb (III) using L-cysteine. This protocol made possible an extensive study of the presence of Sb(III) and Sb(V) in Brazilian samples of bottled mineral water with PET. The mean concentration of Sb (total) for 39 freshly packaged samples was 4 ± 1.4 μg L-1, and 70% of the samples were within the limits acceptable by ANVISA (5.0 μg L-1). The majority species in the samples was Sb(III) with 53 to 79% of the total Sb content, suggesting the migration of Sb2O3 from PET to the beverage. With five brands of bottled mineral water was conducted a study, with samples analyzed for six months. Sb(total) content in mineral water increased from 2 to 27% after 6 months of storage. These results indicate that migration of the Sb present in the PET to the bottled beverage occurs. The migration of Sb from PET to mineral water was evaluated under different storage conditions (time, temperature, sun exposure) using the beverage as simulant and with food simulants (ultrapure water and acid solution). In these tests, when storage temperature increased to 80 °C was observed an increase of up to 214% in Sb content. When samples were exposed for 7 days to solar radiation was observed an increase of up to 323% in Sb content and when packaging were maintained for 10 days with acetic acid simulant was observed an increase of up to 600%. Regarding the distribution of species, the species that presented the most significant increase was Sb(III). The Cr speciation by ultrasound emulsification microextraction involved the selective extraction of Cr (VI) and preconcentration with organic extractor solvent, tributylphosphate (TBP), in HCl and NaCl medium. . It was performed the dispersion of the extractive solution with an ultrasonic bath in place of a dispersing solvent. By the same procedure, the determination of the total Cr(III) content was performed, but after oxidation of Cr(III) to Cr(VI) using KMnO4. A Cr speciation study in samples of natural water from the West, Center-West and Campos Gerais from the State of Paraná, Brazil was carried out. The total concentrations of Cr were less than 1.0 μg L-1,therefore, these levels are compatible with uncontaminated water. Cr dissolved was the largest fraction for the samples, indicating that Cr may have a greater mobility capacity and possible bioavailability in these waters. Regarding the distribution of Cr in the dissolved fraction, the majority fraction was Cr(VI). This is the more toxic specie and more expected form in oxygenated natural waters. The variability in the results shows the need for monitoring of the total concentrations of theses elements and their speciation in aquatic environments and bottled waters, as a way to evaluate their toxicity and guarantee social and environmental security.

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I. Combined cloud point extraction and Tween 20-stabilized gold nanoparticles for colorimetric assay of silver nanoparticles in environmental water This study investigated a simple, sensitive and selective method for the colorimetric assay of silver nanoparticles (AgNPs) using Triton X-114-based cloud point extraction (CPE) as a preconcentration step and Tween 20-stabilized gold nanoparticles (Tween-AuNPs) as a colorimetric probe. After heating beyond the cloud point temperature of Triton X-114, a solution containing Triton X-114 micelles and AgNPs separated into a surfactant-rich phase (small volume) and a dilute aqueous phase. AgNPs partitioned into a Triton X-114-rich phase through a hydrophobic interaction between Triton X-114 micelles and AgNPs. After phase separation, the concentrated AgNPs oxidized to form Ag+ upon adding H2O2. The generated Ag+ triggered the aggregation of Tween 20-AuNPs in a high-ionic-strength solution because the reduction of Ag+ on the AuNP surface enabled Tween 20 (stabilizer) to be removed from the NP surface. The efficiency of Triton X-114-based CPE of the AgNPs was found to be iv insensitive to their size and coating type. Under optimal extraction and detection conditions, the selectivity of this method for AgNPs was considerably higher than for other nanomaterials. The minimum detectable concentrations for 7, 22, and 54 nm AgNPs were measured to be 0.1, 420, and 600 ng/mL, respectively. This method was successfully applied to the analysis of 7 nm AgNPs in drinking water, tap water and seawater. Keyword: silver nanoparticles, gold nanoparticles, cloud point extraction, Tween-20, colorimetric assay II. Functionalized silver nanoparticles as an extracting and preconcentrating agent for detection of mercury ions In this research we provided highly sensitive and selective for fluorescence assay of combined polythymine oligonucleotide (PolyT) with silver nanoparticles (AgNPs) as an extracting agent to detect mercury ion in environmental water. According to previous researches, PolyT will form a hairpin structure in the presence of Hg2+, this structure provide several 3-D grooves that the fluorescent dye can inlay with it. SYBR Green I (SG) is a staining dye for DNA, when binding with single strand DNA, it shows low fluorescence. On the contrast, SG inlay with grooves of hairpin structure, it shows v 11-fold of fluorescence signal. Hence, we used SG as a fluorescence probe for Hg2+. We modified thiol group at the 5¡¦ of PolyT DNA, because of forming silver sulfur bond, PolyT will able to modified on the surface of AgNPs. PolyT33SH-AgNPs are the extracting and concentrating agent in Hg2+ solution, by the centrifugation, we collected the PolyT33SH-AgNPs. For the purpose of releasing PolyT from AgNPs¡¦ surface, we adding H2O2 to oxidize the AgNPs into Ag+. By mixing buffer and SG into previous solution, mercury ion could be detected. In this study, we successfully detecting Hg2+ in the aqueous solution contained drinking water and tap water. The detection limit in drinking water is 20 pM, which is below Environmental Protection Agency limit for Hg2+ in drinkable water (10 nM), the linear range is from 50-600 pM. On the other hand, the detection limit in tap water is 50 pM, linear range is from 100-700 pM. Keyword: silver nanoparticles, mercury ion, PolyT, SYBR Green I, thymine

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As compared with the concentration in sample when the detection limit of analyte is low, a preconcentration method can be used. In this study, cloud point extraction (CPE) was used as the preconcentration method. The aqueous solutions of nonionic and zwitterionic surfactant materials become cloudy when its temperature reaches the cloud point temperature and analyte collapses with surface active material. The volume of surfactant rich phase is much smaller than the solution volume and therefore a way high preconcentration factor was obtained. For the cloud point extraction of selenite, a fluorimetric ligand, 2,3-diminonaphthalene (DAN) was used and the hydrophobic Se(IV)-DAN complex formed (4,5-benzopiazselenol) was extracted with Triton X-114. The effects of pH, complexation period, reaction temperature, DAN concentration and surfactant concentration on the extraction efficiency were investigated. The extraction efficiency at the optimized conditions was 98 percent. Spectrofluorimetric determination of selenium was performed at excitation and emission wavelegths of 379 nm and 582 nm, respectively. The detection limit, established as 3s /slope where s is the standard deviation of 9 measurements of 0.020 mg/L Se (IV)-DAN complex after 10 fold preconcentration was 3.7 &micro / g/L Se. By using solid surface fluorescence measurements detection limit could be reduced down to 1.2 &micro / g/L. The obtained detection limits (3.7 and 1.2 &micro / g/L) were sufficiently low for detecting selenite in diverse samples. The accuracy of the method was confirmed by the analysis of trace elements in waste water Standard reference material (EnviroMAT- Waste Water LOW EU-L-1). The interference effects of some anions and cations were also tested.

Selenium is a trace and essential element for good health but required only in very narrow range. Hence, determination of selenium in trace level in any matrix related with human health is important. A preconcentration method is performed to obtain a low detection limit for analyte. In this study, the methodology of cloud point extraction (CPE) was used as the preconcentration method for speciation of selenium in vitamin tablets. Non-ionic surfactant Triton X-114 and a fluorimetric ligand, 2,3- diaminonaphtalene (DAN) were used for the extraction of trace levels of organic and inorganic selenium species as a prior step to their determination by spectrofluorimetry. The aqueous solutions of nonionic and zwitterionic surfactant materials become cloudy when temperature reaches the cloud point temperature and analyte collapses with surface active material. The volume of surfactant rich phase is smaller than the solution volume and by this way high preconcentration factor was obtained. Optimization of the CPE parameters affecting complexation and phase separation was performed. Standard addition method was used in the quantitative measurements. Spectrofluorimetric determination of selenium was done using excitation and emission wavelegths of 380 nm end 570 nm respectively. The detection limit, established as 3s /slope where s is the standard deviation of 12 measurements of 0.02 mg/L Se-DAN complex after 10 fold preconcentration was 2.3 &micro / g/L. Accuracy of the method was checked using EnviroMat Waste Water, EU-L-2 as SRM and the result was in good agreement with certified value.Besides, selenium rich vegetables (dill, watercress herb and garlic) were grown in a pot at a controlled atmosphere.Selenium in plants (dill, watercress gerb and garlic), both control and enriched groups was determined by ICP-MS.

Orientadora: Profa. Dra. Lúcia Helena Gomes Coelho / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência e Tecnologia Ambiental, 2016. / O uso de pesticidas na agricultura e um dos principais fatores de poluicao do solo e das aguas superficiais e subterraneas, sendo potencialmente danoso ao ambiente e a saude humana. Comumente, os residuos de pesticidas estao presentes em concentracoes baixas, o que torna necessaria a extracao e pre-concentracao do analito a fim de elevar a detectabilidade dessas substancias. Neste trabalho, avaliou-se a viabilidade tecnica de aplicacao da metodologia para extracao e pre-concentracao de tracos do herbicida Paraquat, presente em amostras de agua, por extracao em ponto nuvem, minimizando a utilizacao de solventes organicos toxicos e a geracao de residuos, estrategias de preparo de amostra de grande interesse para as areas de tecnologias verdes. Os procedimentos foram realizados utilizando-se diferentes surfactantes: nao ionico (Triton X-114) e ionicos (SDS ¡V anionico e CTAB ¡V cationico). Testou-se a influencia de composto ionico na amostra para auxiliar a separacao das fases e observou-se que, para o sistema SDS/CTAB, a adicao de 10% de NaCl (m/v) ajudou na separacao da fase micelar em relacao a fase aquosa, porem este sistema nao foi eficaz para a extracao do Paraquat devido ao aspecto coloidal da fase organica. Para o Triton X-114, o composto ionico nao apresentou diferenca significativa na separacao das fases, nao justificando a utilizacao do reagente. Este sistema apresentou resposta linear para solucoes entre 0,2 e 5,0 mg L-1 de Paraquat, com FE de 71 e recuperacao entre 62 e 100% para concentracao de 3 mmol L-1 em surfactante, e, FE 45 e recuperacao de 100% para 6 mmol L-1 em surfactante. A solucao de Triton X-114 3 mmol L-1 apresentou repetibilidade em suas extracoes, com coeficiente de variacao medio de 15,5%, porem nao foi reprodutivel. Para quantificacoes em amostras reais, fez-se necessaria a reacao com ditionito para seletividade do Paraquat, pois substancias presentes na amostra podem ser extraidas e absorverem no mesmo comprimento de onda que o analito de interesse (¿Ü = 258 nm). Os limites de deteccao e quantificacao foram, respectivamente, 15 e 50 £gg L-1 para a leitura direta e 50 e 167 £gg L-1 para a determinacao colorimetrica. Contudo, a aplicacao em amostras reais nao apresentou a mesma eficiencia de pre-concentracao e extracao, sobretudo pela elevada solubilidade do Paraquat em agua, concluindo-se que a tecnica nao se mostrou a mais adequada para a aplicacao proposta. A quantificacao por colorimetria e uma alternativa interessante a determinacao por HPLC por ser mais rapida, menos laboriosa e de menor custo, alem do residuo ser de mais facil disposicao que os solventes organicos convencionalmente utilizados em cromatografia. / The use of pesticides in agriculture is one of the main factors of soil, surface and groundwater pollution, and they are potentially harmful to the environment and human health. Pesticides residues are commonly present at low concentrations, which makes necessary an extraction and pre-concentration step of the analyte in order to increase the detectability of these substances. In this work, it was evaluated the feasibility of application of the extraction and pre-concentration of traces of the herbicide Paraquat present in water samples, using cloud point extraction methodology, minimizing the use of toxic organic solvents and the generation of residues, which are considered strategies of sample preparation with huge interest for green technologies. The procedures were performed using different surfactants: nonionic (Triton X-114) and ionic (SDS - anionic and CTAB - cationic). It was tested the influence of ionic compounds in the sample to aid phase separation and it was observed that, for SDS/CTAB system, the addition of 10% NaCl (w/v) helped the micellar phase separation, but this system was not effective for Paraquat extraction once the organic phase produced had a colloidal aspect . For the Triton X-114, the ionic compound was no significant difference, not justifying the use of the reagent. This system showed linear response between 0.2 and 5.0 mg L-1 of Paraquat, with enrichment factor of 71 and recovery between 62 and 100% with the concentration of 3 mmol L-1 in tensoative, and, enrichment factor 45 to 100% recovery for 6 mmol L-1 in surfactant. The solution of Triton X-114 3 mmol L-1 showed repeatability in the cloud point extraction, with mean variation coefficient of 15.5%, but it was not reproducible. For the measurements using real samples, it was necessary a prior reaction with dithionite for selectivity detection of Paraquat, once many substances present in the water sample can be simultaneously extracted and analysed at the same wavelength as the target analyte (ë = 258 nm). The limits of detection and quantification were, respectively, 15 and 50 ìg L-1 for the direct analysis and 50 and 167 ìg L-1 for the colorimetric determination. However, the application in real samples did not show the same efficiency of pre-concentration and extraction, especially because Paraquat has high solubility in the water, concluding that the technique was not the most suitable for the proposed application. The colorimetric quantification is an interesting alternative to HPLC determination because it is faster, less laborious and lower cost, in addition to generating an easier disposition residue than conventionally organic solvents used in chromatography.