Neste trabalho é apresentado um estudo referente à sorção do complexo cobre-dietilditiocarbamato, empregando espuma de poliuretano (EPU) como fase sólida. Foi observado que em pH 6,8 e na presença de DDTC 4,5 x 10 -5 mol L -1 a sorção de Cu(II) (80 ou 150 µg L -1 ) foi máxima. O tempo requerido para que o equilíbrio fosse alcançado foi de 40 min. A partir dos dados deste experimento foi realizada uma caracterização cinética através da aplicação de três modelos, que revelaram que a difusão do complexo na interface entre sólido-líquido foi a etapa determinante na velocidade do processo sortivo. Pôde-se também afirmar que a sorção do complexo se dá através de um mecanismo similar aquele observado em extração líquido-líquido, usando éter como solvente. Testes com possíveis interferentes demonstraram a relativa seletividade da extração do complexo metálico, que pode ser melhorada com a presença de um agente mascarante adequado. This paper presents a study about the sorption of copper-diethyldithiocarbamate complex onto polyurethane foam (PUF). It was observed that the maximum sorption of Cu(II) (80 or 150 µg L -1 ) was verified at pH 6.8 in presence of 4.5 x 10 -5 mol L -1 DDTC. The shaking time needed to achieve the equilibrium was 40 minutes. From these data, a kinetic characterization was performed by applying three models, which revealed that a film diffusion process was a rate-determining mechanism. Results also indicated that a ether-like solvent extraction was the sorption mechanism. The investigation of many metallic ions as concomitants showed that the sorption by foam is relatively selective and it can be enhanced by using a suitable masking agent or incrementing the foam mass.Keywords: solid phase extraction, polyurethane foam, diethyldithiocarbamate, copper IntroductionNowadays, the removal of toxic substances from aqueous medium such as effluents is of great interest for environmental and human health purposes. For this reason, the control and treatment of these effluents have become one of the most important steps of the productive process. In this scenario, the application of solid phase extraction (SPE) procedures has increased in last few years, specially due to its efficiency and low requirements in terms of cost. 1 Among several other solid phases employed in SPE methodologies, 2-5 the use of polyurethane foams (PUF) has grown up since publication of the pioneer work of Bowen. 6 Various research papers were published describing the use of unloaded foams for analytical preconcentration and separation of organic and inorganic species in aqueous medium. [7][8][9][10][11] Additionally, the polyurethane foams have been used as solid supports for specific reagents 12-14 which, according to the literature, leads to SPE procedures with high selectivity and analytical throughput. 15 Also, some papers have focused the characterization of the sorption process by studying the kinetics and thermodynamics aspects related to the extraction. [16][17][18] It is well known that the reaction between diethyldithiocarb...

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Este trabalho apresenta um método para a determinação de chumbo por ETAAS, baseado na amostragem sólida da espuma de poliuretano impregnada com o reagente 2-(2-tiazolilazo)-p-cresol (TAC) previamente utilizada para extrair o íon metálico da solução amostra. O processo de extração ocorreu em pH 10, tamponado com sistema borato, após 40 min de agitação das fases sólida e líquida. Os resultados obtidos mostraram a fácil eliminação da matriz do tubo de grafite, utilizando como pirólise a temperatura de 600 ºC, sem a adição de modificador químico de matriz. O método desenvolvido foi validado através da análise de materiais certificados de referência (amostras biológicas) e através de testes de recuperação em amostras salinas. This work presents a method for lead determination by ETAAS, based on solid sampling of polyurethane foam (PUF) impregnated with the reagent 2-(2-thiazolylazo)-p-cresol (TAC) previously utilized to extract the metallic ion from sample solution. The extraction process occurred in a medium buffered in pH 10 with borate system, after 40 min of agitation between the solid and liquid phases. The obtained results showed the easily elimination of the matrix from the graphite tube by a pyrolysis step at 600 ºC, without using of any matrix modifier. The method was validated by analysis of certified materials (biological samples) and by using recovery tests employing saline samples.

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