CLOUD POINT EXTRACTION/PRECONCENTRATION OF COPPER IONS EXPLOITING THE FORMATION OF COMPLEXES WITH DMIT [4,5-DIMERCAPTO-1,3-DITHYOL-2-THIONATE]

CLOUD POINT EXTRACTION/PRECONCENTRATION OF COPPER IONS EXPLOITING THE FORMATION OF COMPLEXES WITH DMIT [4,5-DIMERCAPTO-1,3-DITHYOL-2-THIONATE]. The present study proposes a method for cloud point preconcentration of copper ions at pH 2.0 based on complexes formed with [4,5-dimercapto-1,3-dithyol-2-thionate] and subsequent determination by flame atomic absorption spectrometry (FAAS). Under optimal analytical conditions, the method provided limits of detection of 0.84 and 0.45 mu g L-1, by preconcentrating 12.0 and 24.0 mL of sample, respectively. The method was applied for copper determination in water samples, synthetic saliva, guarana powder, tea samples and soft drinks and the accuracy was assessed by analyzing the certified reference materials Dogfish Liver (DOLT-4) and Lobster Hepatopancreas (TORT-2).3581600160

3-mercaptopropyltrimethoxysilane-Modified Multi-walled Carbon Nanotubes as a New Functional Adsorbent for Flow Injection Extraction of Pb(II) from Water and Sediment Samples

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)In the present study, a novel synthesized adsorbent material based on 3-mercaptopropyltrimethoxysilane-functionalized multi-walled carbon nanotubes was used to increase the Pb2+ adsorption from aqueous solutions in a flow injection solid-phase extraction system coupled to flame atomic absorption spectrometry. Spectroscopic and microscopic techniques (Fourier transform infrared spectroscopy, energy dispersive spectroscopy, and scanning electronmicroscopy) were employed to confirm the chemical modification of the adsorbent surface. Preconcentration conditions (sample pH, flow rate, buffer solution, and eluent concentrations) were optimized using factorial and Doehlert matrix designs that made it possible to construct a linear graph in the 5.0- to 130.0-mu gL(-1) range (r=0.9999) and estimate detection and quantification limits (1.7 and 5.7 mu gL(-1), respectively). The method precision was found to be 4.20 and 1.97% for 5.0 and 100.0 mu gL(-1) Pb2+ solutions, respectively. When using the 3-mercaptopropyltrimethoxysilane-functionalized multi-walled carbon nanotubes, the sensitivity for the Pb2+ trace determination was improved to 95 % compared with the oxidized multi-walled carbon nanotubes, thus evidencing the significant enhancement of the adsorption capacity. The developed method was successfully applied to the analysis of Pb2+ species in different water samples and the PACS-2 marine sediment-certified reference material.223960696081Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Instituto Nacional de Ciencia e Tecnologia de Bioanalitica (INCT)Fundacao Araucaria do ParanaFAEPE-UELConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES