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Sasaki MK, Rocha DL, Rocha FRP, et al. Tracer-monitored flow titrations. Anal Chim Acta. 2015;902:123-128doi: 10.1016/j.aca.2015.10.036.
Sasaki, M. K., Rocha, D. L., Rocha, F. R. P., & Zagatto, E. A. G. (2016). Tracer-monitored flow titrations. Analytica chimica acta, 902123-128. https://doi.org/10.1016/j.aca.2015.10.036
Sasaki, Milton K, et al. "Tracer-monitored flow titrations." Analytica chimica acta vol. 902 (2016): 123-128. doi: https://doi.org/10.1016/j.aca.2015.10.036
Sasaki MK, Rocha DL, Rocha FRP, Zagatto EAG. Tracer-monitored flow titrations. Anal Chim Acta. 2016 Jan 01;902:123-128. doi: 10.1016/j.aca.2015.10.036. Epub 2015 Nov 06. PMID: 26703261.
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Anal Chim Acta. 2016 Jan 01;902:123-128. doi: 10.1016/j.aca.2015.10.036. Epub 2015 Nov 06.

Tracer-monitored flow titrations.

Analytica chimica acta

Milton K Sasaki, Diogo L Rocha, Fábio R P Rocha, Elias A G Zagatto

Affiliations

  1. Center for Nuclear Energy in Agriculture, University of Sao Paulo, Brazil.
  2. Center for Nuclear Energy in Agriculture, University of Sao Paulo, Brazil. Electronic address: [email protected].

PMID: 26703261 DOI: 10.1016/j.aca.2015.10.036

Abstract

The feasibility of implementing tracer-monitored titrations in a flow system is demonstrated. A dye tracer is used to estimate the instant sample and titrant volumetric fractions without the need for volume, mass or peak width measurements. The approach was applied to spectrophotometric flow titrations involving variations of sample and titrant flow-rates (i.e. triangle programmed technique) or concentration gradients established along the sample zone (i.e. flow injection system). Both strategies required simultaneous monitoring of two absorbing species, namely the titration indicator and the dye tracer. Mixing conditions were improved by placing a chamber with mechanical stirring in the analytical path aiming at to minimize diffusional effects. Unlike most of flow-based titrations, the innovation is considered as a true titration, as it does not require a calibration curve thus complying with IUPAC definition. As an application, acidity evaluation in vinegars involving titration with sodium hydroxide was selected. Phenolphthalein and brilliant blue FCF were used as indicator and dye tracer, respectively. Effects of sample volume, titrand/titrant concentrations and flow rates were investigated aiming at improved accuracy and precision. Results were reliable and in agreement with those obtained by a reference titration procedure.

Copyright © 2015 Elsevier B.V. All rights reserved.

Keywords: Acidity; Flow analysis; Spectrophotometry; Tracer-monitored titration; Vinegars

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