A new approach to construct diffusion/permeation cell for use in flow systems: application in the spectrophotometric determination of bicarbonate ions

• Autor(a) principal: Oliveira,Paulo C. C. de
• Data de Publicação: 2006
• Outros Autores: Masini,Jorge C., Galhardo,Cristiane X., Lima,José C. de S., Sant'ana,Antonio E. G., Vasconcelos,Ana M. G., Nunes,Wanessa P., Amaral,Osvaldo L. C.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Journal of the Brazilian Chemical Society (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532006000500023
• topic: gas-diffusion device; flow injection analysis; bicarbonate ions

This work describes a new approach for construction of gaseous diffusion/permeation module in a configuration based on the perfect fitting between two plaques of acrylic. It was employed to determine bicarbonate ions exploiting the discoloration of a 0.01% (m/v) phenolphthalein solution in medium of 1.0 x 10-5 mol L-1 NaOH (pH 9.0). The variation in the indicator color was monitored at 552 nm. The analytical curve showed a working range between 25.0 and 150.0 mg L-1 in NaHCO3. Consecutive injections (n=10) of a standard 5.0 mg L-1 NaHCO3 solutions exhibited less than 1.0% of relative standard deviation. The correlation coefficient of analytical curve was 0.9996 and the limit of detection (3 x noise/slope) is 4.41 mg L-1 in NaHCO3. The proposed method is rapid (50 sample/hour) and results were in good agreement with the ones obtained by classical titrimetry.