Direct Determination of Phosphite in Fertilizers by Amperometric Titration
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Data
2009-01-28
Autores
Franzini, Vanessa P. [UNESP]
de Moraes, Mercedes [UNESP]
Gomes Neto, José Anchieta [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Amer Chemical Soc
Resumo
Amperometric titration using two Pt microelectrodes for the determination of phosphite in fertilizers based on the oxidation of analyte by iodine is proposed. The influence of pH, buffer composition, temperature, and foreign species on the end point and titration time was investigated. For titrations carried out at 70 degrees C using the pH 6.8 phosphate buffer, samples containing ca. 0.4% (m/v) P(2)O(5) could be titrated with 0.050 mol L(-1) iodine titrant, and the end point determined by extrapolating the linear portions of the plot to their intersection coincided with the end point identified by spectrophotometry. Accuracy was checked for phosphite determination in five fertilizer samples. Results were in agreement at the 95% confidence level (paired t test) with spectrophotometry. Recoveries of phosphite added to fertilizer samples ranged from 97% to 102% regardless of the amount of spiking in several determinations. The relative standard deviation (n = 10) was 1.0% for a diluted sample containing 0.050 mol L(-1) Na(2)HPO(3).
Descrição
Palavras-chave
Phosphite, direct determination, titrimetry, iodine
Como citar
Journal of Agricultural and Food Chemistry. Washington: Amer Chemical Soc, v. 57, n. 2, p. 372-374, 2009.