Extração de elementos traços da água do mar por coprecipitaçao e determinação por ICP-MS

• Autor(a) principal: Conceição, Vitor Nunes da
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/11164
• topic: Seawater; Trace elements; Coprecipitation; Água do mar; Elementos traço; Coprecipitação; ICP-MS; Química; Espectrometria de massa; 54

The quality of the oceans has been constantly changing at different scales, as a consequence of natural and mainly anthropic factors. The industrial, mining and agricultural activities have contributed significantly to the increase of trace element concentration in marine environments, impacting directly on its ecosystem and public health. In view of the above, the determination and monitoring of trace elements insea water is of great importance. Inductively coupled plasma mass spectrometry (ICP-MS) is widely used for the determination of trace elements in sea water, however, there is a great challenge because the salt matrix is considered complex, causing numerous spectral and non-spectral Thus, it is necessary to study trace element extraction methodologies in this matrix. In this sense, the present work initially aimed at the determination of As, Cr, Cu, Mn and Pb in sea water by ICP-MS in the standard mode (without reaction cell and collision) after the precipitation of the present Mg2+ion in the seawater with ammonia, forming Mg(OH)2, and coprecipitation of some trace elements. Multivariate statistical tools such as central composite planning, desirability function and response surface methodology were used to optimize the coprecipitation procedure. The optimal values obtained for 45 mL of sample were 1200 µL of concentrated aqueous ammonia, 30 minutes of centrifugation time and 400 µL of concentrated nitric acid. After the optimization, extraction tests were performed with other trace elements with coprecipitation, where good results were obtained for Co, thus, the element was included in the following studies. The obtained procedure had low detection limits in the sample (0.02 to 3.71 ng L-1), since good preconcentration factors were obtained. Accuracy of the method was verified by Trace Metals 1 certified reference material in seawater analyzes and the recovery percentage test (60.5 to 105.8%). Thus, the proposed procedure can be considered a good strategy for the determination of As, Co, Cr, Cu, Mn and Pb in sea water by ICP-MS, due to its simplicity and low cost, besides the good sensitivity and accuracyachieved.