ESPECIAÇÃO DE Cr(III) E Cr(VI) USANDO SISTEMA DE PRÉ-CONCENTRAÇÃO EM FLUXO, MINICOLUNA C18 COM DETECÇÃO POR FAAS

• Autor(a) principal: Pereira, Catarinie Diniz
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações do UNICENTRO
• Texto Completo: http://localhost:8080/tede/handle/tede/275
• topic: especiação; crômio; pré-concentração; análise em fluxo; speciation; chromium; pre-concentration; flow analysis; CIENCIAS EXATAS E DA TERRA::QUIMICA

This work aimed to develop and optimize an analytical method for chromium speciation in the dissolved fraction of natural water samples. In addition, determinations of total chromium have been made in the solid particulated fraction as well as in the sediment collected in the delimited area of the study. Determination of additional parameters: temperature, chemical oxygen demand (COD), biochemical oxygen demand (BOD), pH, dissolved oxygen (DO), total dissolved solids (TDS), total suspended solids (TSS), color, turbidity, Fe, Mn, nitrate, nitrite, sulfate, sulfide, chloride, they have all been carried out for characterization of the aquatic environment on study. An automatic flow system was developed for chromium speciation based on solid phase complexation and sortion. This system was able to enrich the species studied (Cr(III) and Cr(VI)), present in the original aquatic matrix. The Xylenol orange for Cr(III) and 1,5-diphenylcarbazide for Cr(VI) has been used as a complexing agent. For both species, retention of the complex has been applied in minicolumn with C18, elution with methanol and flame atomic absorption spectrometric determination. For Cr(III), the results obtained ranged from 5,2 to 105,2 μg/Land for Cr(VI) all the determinations were below the detection limit; 2,5 μg/L.For determination of total chromium in the particulated fraction and in the sediment, acid digestion and flame atomic absorption spectrometric determination have been applied. For the solid particulated fraction the results obtained ranged from 449,0 to 9324,0 mg/kg and for the sediment it ranged from 873,0 to 1691,8 mg/kg. Of the additional parameters determined, iron has been the most critical due to its interference when determining Cr(III) and Cr(VI). In order to minimize this effect, analytical curves for both chromium species have been carried out in the presence of variable concentrations of iron. Thus, it was possible to correct the results obtained for chromium in the environmental samples and to previse a contamination.