Orientador: Profa. Dra. Ivanise Gaubeur / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Ciência e Tecnologia/Química, 2015. / O cromo e utilizado em varias atividades industriais e com o aumento da sua presenca no ambiente se tem uma preocupacao em relacao a contaminacao ambiental e considerando que as duas principais especies do elemento quimico apresentam diferentes efeitos na saude humana e importante a realizacao da especiacao quimica. Este trabalho propoe o desenvolvimento de metodo analitico para especiacao de cromo combinada a microextracao liquido-liquido dispersiva com gota organica flutuante (DLLME-FO) e deteccao por espectrometria de absorcao atomica com chama de fonte continua com alta resolucao (HR-CS F AAS). As variaveis que afetam a complexacao (valor de pH, tipo e concentracao dos complexantes: dietilditiocarbamato de sodio (DDTC) e pirrolidinaditiocarbamato de amonio (APDC), microextracao (volume dos solventes dispersor e extrator e concentracao salina) e deteccao como a composicao da chama foram otimizadas de forma univariada e multivariada. Apos as otimizacoes foram escolhidas como melhores condicoes para complexacao, o complexante APDC (6,0x10-3 mol L-1) e valor de pH 2,0 e 7,0, para Cr(VI) e cromo total, respectivamente. E as condicoes da microextracao foram: 5%(m/v) de NaCl, 50 ¿ÊL de 1-undecanol (solvente extrator) e 300 ¿ÊL e 275 ¿ÊL de etanol (solvente dispersor). As caracteristicas analiticas obtidas foram: faixa linear de 20-100 ¿Êg L-1 para Cr(VI) e cromo total. Para o Cr(VI) foram obtidos limite de deteccao 0,35 ¿Êg L-1, coeficiente de variacao igual a 7% (n=10) e fator de enriquecimento igual a 14. Para o cromo total foram obtidos limite de deteccao 6,7 ¿Êg L-1, coeficiente de variacao igual a 18% (n=10) e fator de enriquecimento igual a 10. A exatidao foi avaliada em material de referencia certificado de agua e as concentracoes determinada e certificada foram concordantes em um nivel de confianca de 95%. O metodo foi aplicado em amostras de agua e as concentracoes de cromo encontradas estao dentro dos limites estabelecidos pelas legislacoes vigentes. / Chromium is used in various industrial activities and increasing its presence in the environment has been a concern in relation to environmental contamination and considering that the two main species of the chemical element have different effects on human health is important the realization of chemical speciation.This work proposes the development of analytical method for chromium speciation combined dispersive liquid-liquid microextraction based on floating organic drop (DLLME-FO) and detection by high-resolution continuum source flame atomic absorption spectrometric (HR-CS F AAS) . The variables that affect the complexation (pH, type and concentration of complexant: sodium diethyldithiocarbamate (DDTC) and ammonium pyrrolidinedithiocarbamate (APDC), microextraction (volume of disperser and extractant solvents and salt concentration) and detection as the composition of the flame were optimized using univariate and multivariate analysis. After the optimizations were chosen as the best conditions for complexing the complexant APDC (6.0x10-3 mol L-1) and pH value 2.0 to 7.0 for Cr (VI) and total chromium, respectively. And the microextraction conditions were: 5% (w/v) NaCl, 50 ìL of 1- undecanol (extractant solvent) and 300 ìL of ethanol and 275 ìL (disperser solvent). The analytical characteristics were obtained: linear range of 20-100 ìg L-1 to Cr (VI) and total chromium. For the Cr (VI) was obtained limit of detection 0.35 ìg L-1, coefficient of variation 7% (n=10) and enrichment factor of 14. For the total chromium was obtained limit of detection 6.7 ìg L-1, coefficient of variation 18% (n=10) and enrichment factor of 10. The accuracy was evaluated in water certificate reference material and determined and certified concentrations were agreed at the 95% confidence level. The method was applied to water samples and chromium concentrations found are within the limits established by current legislation.