Um analisador fluxo-batelada com bomba-pistÃo aplicado à preparaÃÃo de soluÃÃes de calibraÃÃo e microemulsÃes: determinaÃÃo de metais em Ãgua mineral e gasolina por GF AAS

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The development of flow analyzers and continuous monitoring of some chemical processes have lead to the design of flow manifolds more cheap and simplified, with potential for miniaturization. For these purposes, the use of flow systems seems to be an attractive option. Among these systems, the Flow-batch analyzers (FBA) were applied with success in the implementation of several analytical procedures, such as: titrations, sample pre-treatment, analyte addition and screening analysis. Despite their favorable characteristics, the FBA analyzers previously proposed make use of peristaltic pumps for the fluids propulsion. The use these pumps can elevate the analyzer costs and may become unfeasible its miniaturization due to the great dimensions of the models commercially available. To overcome these drawbacks, it is proposed in this work a low cost, compact based on pneumatic propulsion of the fluids. This system makes use of a lab made piston-pump, which consists of a stepper motor mechanically connected to a metallic piston and controlled by microcomputer, coupled to an adapted mixing chamber. The proposed analyzer was applied the calibration solutions automatic preparation for manganese determination in mineral waters for of graphite furnace atomic absorption in spectrometry (GF AAS). For comparison ends, two sets of calibration solutions (four points each) were prepared, manually and automatically, resulting in the construction of five calibration curves, for each preparation method used. Significant statistical differences among the results were not observed by the application of a statistical test (t-student) for a 95% confidence level. The standard deviations of the manual and automatic procedures were always smaller or equal to 0.1 μgÂL-1, with capacity to process up to 80 calibration solutions h-1. After the verification of its use viability, the proposed analyzer was also applied to gasoline sample analysis using a pre-treatment based on microemulsions of this sample for copper determination by GF AAS. After the accomplishment of studies and assays regarding to the microemulsions developed for this work, and optimization of the analyzer operational parameters, were performed the analysis of the gasoline samples pre-treated automatically. Even with the problems presented in the analysis of the microemulsions automatically prepared, it was verified the applicability of the developed analyzer for on line preparation of calibration solutions and microemulsions, with versatility, simplicity, flexibility, robustness, without the characteristic peristaltic pumping pulsation and low operational costs was demonstrated. Moreover, this system can also be used for in situ analyses, because, due to their small dimensions, it can become portable after simple adaptations

ASSUNTO(S)

anÃlise de Ãgua mineral manganese microemulsÃes mineral water analysis gf aas microemulsions copper gasoline analysis anÃlise de gasolina fluxo-batelada manganÃs flow-batch cobre gf aas quimica

ACESSO AO ARTIGO

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