Tracer-monitored flow titrations

Autor(es)

Sasaki, Milton K. ^[1] ; Rocha, Diogo L. ^[1] ; Rocha, Fabio R. P. ^[1] ; Zagatto, Elias A. G. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Ctr Nucl Energy Agr, BR-13400970 Piracicaba - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Analytica Chimica Acta; v. 902, p. 123-128, JAN 1 2016.
• Citações Web of Science: 4

Resumo

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 ELF were used as indicator and dye tracer, respectively. Effects of sample volume, titrandititrant 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. (C) 2015 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 11/14413-0 - Comparação entre analisadores com fluxo laminar ou pulsado e reagentes imobilizados: aplicação a amostras de relevância farmacêutica, agronômica e/ou ambiental
• Beneficiário: Milton Katsumi Sasaki
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 11/23498-9 - Sistemas avançados de análises químicas em fluxo: aplicações nas áreas tecnológica, agronômica e ambiental
• Beneficiário: Elias Ayres Guidetti Zagatto
• Modalidade de apoio: Auxílio à Pesquisa - Temático