Desenvolvimento de sistemas automatizados de adições padrão e eliminação de interferencias em analise espectrofotometricas de rochas, minerais e ligas pela aplicação do metodo generalizado de adições padrão

AUTOR(ES)
DATA DE PUBLICAÇÃO

1987

RESUMO

Correction for the chemical, physical, spectra and/or matricial interferences by standard addition methods generally requires preparation and addition to the sample of a serie of standard solutions. If manual addition procedures are employed, they, besides being tedious, usually involve a relatively large consumption of reagents and samples and a low analytical rate. Further, they may lead to contamination resulting from the large number of analytical steps (for example, pipetting) involved. To overcome these problems, three systems of standard addition which utilize the flow injection analysis (FIA) technique were developed in this work - a system based on the confluent zones process (APZC); one based on the variation of volume injected (APVVI) and one based on exploration of concentration gradients(APEGC). For the APEGC system, a data acquisition and contral process was developed using a microprocessor kit, coupled to a microcomputer charged with storing and mathematical treatment of the data. The systems developed in this work were applied to the simultaneous analysis of Ni, Cu and Zn in nickel-copper alloy, using inductively coupled plasma atomic emission spectroscopy: Ca, Na and K in certified samples of limestone, cement and phosphatic rock, using flame photometry and Ni, Co, Cu and Cr2O7 in synthetic samples, using UV-Visible molecular absorption spectrometry. The generalized standard addition method was used to correct for intercomponent interference effects. The time necessary for the complete procedure which involves the determination of a component was generally around 10 min for the APZC and APVVI systems and 2 min for the APEGC system. The relative standard deviations of the results obtained were always lower than 3%. In the analysis of certified samples, a good agreement was always found between the experimental and theoretical values. Thus, apart from minimizing the principal disadvantages of manual addition procedures, the use of FIA systems renders the standard addition technique very much more attractive from the practical point of view and resolves the interference problems without undue delay.

ASSUNTO(S)

quimica analitica espectrofotometria

ACESSO AO ARTIGO

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