ISSN: 1546-962X
CODEN: JAIOAD
Published Online: 21 December 2009
Page Count: 7

Water Content Determination in Biodiesel: Optimization of Methodology in Coulometric Karl Fischer Titration

Vicentim, M. P.
Laboratório de Análise Orgânica, Divisão de Metrologia Química, DIMCI/INMETRO, 50 Prédio 6, Xerém, Duque de Caxias, Rio de Janeiro

Barreto Sousa, M. V.
Laboratório de Análise Orgânica, Divisão de Metrologia Química, DIMCI/INMETRO, 50 Prédio 6, Xerém, Duque de Caxias, Rio de Janeiro

Fernandes da Silva, V.
Laboratório de Análise Orgânica, Divisão de Metrologia Química, DIMCI/INMETRO, 50 Prédio 6, Xerém, Duque de Caxias, Rio de Janeiro

Mateus, V. Lionel
Laboratório de Análise Orgânica, Divisão de Metrologia Química, DIMCI/INMETRO, 50 Prédio 6, Xerém, Duque de Caxias, Rio de Janeiro

Rodrigues, J. M.
Laboratório de Análise Orgânica, Divisão de Metrologia Química, DIMCI/INMETRO, 50 Prédio 6, Xerém, Duque de Caxias, Rio de Janeiro

Smarçaro da Cunha, V.
Laboratório de Análise Orgânica, Divisão de Metrologia Química, DIMCI/INMETRO, 50 Prédio 6, Xerém, Duque de Caxias, Rio de Janeiro

(Received 12 June 2009; accepted 13 November 2009)

Abstract

Coulometric Karl Fischer (KF) titration is a highly accurate technique employed for moisture determination in non-aqueous solvents. Methodology for coulometric titration in a KF apparatus coupled to an autosampler oven was optimized in order to improve the accuracy of moisture determination in biodiesel derived from soybean. Several parameters were investigated, and three of them were optimized according to a central composite 2³ star experimental design. The highest accuracy for moisture determinations corresponded to a relative standard deviation of 1.48 %. It was reached when the KF titrator was operated with electrode without diaphragm, the sample mass was 4 g, and the oven temperature was set to 170°C. Other parameters, like carrier gas flux and extraction time, presented minimal or no effects for improving the accuracy of moisture determination.

Keywords:
biodiesel, Karl Fischer titration, moisture, soybean

Paper ID: JAI102615
DOI: 10.1520/JAI102615
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