Gran method for end point anticipation in monosegmented flow titration

Abstract

Este trabalho descreve o uso do método de linearização de Gran em titulações em fluxo monossegmentado com detecção potenciométrica. O programa de controle pode estimar o ponto final após a adição de três ou quatro alíquotas de titulante. Alternativamente, o ponto final da titulação pode ser determinado pelo método da segunda derivada. Neste caso, alíquotas adicionais de titulante são adicionadas até a proximidade do ponto final e três pontos antes e após o ponto estequiométrico são usados para o cálculo de ponto final. O desempenho do sistema foi avaliado pela determinação de cloreto em soluções isotônicas e parenterais. O sistema emprega um eletrodo indicador tubular de Ag 2 S/AgCl. Uma titulação típica, realizada de acordo com a definição IUPAC, requer apenas 60 µL de amostra e aproximadamente o mesmo volume de titulante (AgNO 3). Uma titulação completa pode ser realizada entre 1 e 5 min. Foram obtidas exatidão e precisão (desvio padrão relativo de 10 replicatas) de 2% e 1% para o método de Gran e 1% e 0,5% para o método de Gran associado ao método da segunda derivada, respectivamente. O sistema proposto reduz o tempo para realizar uma titulação, com baixo consumo de amostra e reagente, além de possibilitar uma amostragem automática completa e adição de titulante sem a necessidade de uma etapa de calibração. An automatic potentiometric monosegmented flow titration procedure based on Gran linearisation approach has been developed. The controlling program can estimate the end point of the titration after the addition of three or four aliquots of titrant. Alternatively, the end point can be determined by the second derivative procedure. In this case, additional volumes of titrant are added until the vicinity of the end point and three points before and after the stoichiometric point are used for end point calculation. The performance of the system was assessed by the determination of chloride in isotonic beverages and parenteral solutions. The system employs a tubular Ag 2 S/AgCl indicator electrode. A typical titration, performed according to the IUPAC definition, requires only 60 µL of sample and about the same volume of titrant (AgNO 3) solution. A complete titration can be carried out in 1-5 min. The accuracy and precision (relative standard deviation of ten replicates) are 2% and 1% for the Gran and 1% and 0.5% for the Gran/derivative end point determination procedures, respectively. The proposed system reduces the time to perform a titration, ensuring low sample and reagent consumption, and full automatic sampling and titrant addition in a calibration-free titration protocol.

Monosegemented flow potentiometric titration for the determination of chloride in milk and wine

“…This limitation has been observed by other authors. 30 In the present work, solutions with concentrations lower than 3.0 x 10 -2 mol L -1 could be employed without risks of clogging the system. Some experiments were also performed employing the SIA approache.…”

pHbot: Self‐Driven Robot for pH Adjustment of Viscous Formulations via Physics‐informed‐ML**

“…The advantage of this technique is that the characterisation of the endpoint is generally less dependent on the speed of measurement. A second advantage is that throughput of discrete batch titration can be increased by using a discrete flow titration, where each unique ratio is continuously generated, typically by syringe pumps, and the endpoint is detected inline [21,22] …”

“…A second advantage is that throughput of discrete batch titration can be increased by using a discrete flow titration, where each unique ratio is continuously generated, typically by syringe pumps, and the endpoint is detected inline. [21,22] Our design process is detailed in the decision tree shown in Figure 3. The high viscosity of our analyte precluded the use of discrete flow titration due to its tendency to clog and the difficulty of completely removing residue from tubing walls between discrete flow units.…”

Novel approach for mono-segmented flow micro-titration with sequential injection using a lab-on-valve system: a model study for the assay of acidity in fruit juices

“…Thus, longer resident time and better sensitivity with low reagent consumption can be achieved. [31][32][33][34][35] We propose the new concept of mono-segmented flow micro-titration using a sequential injection analysis-lab-onvalve (SIA-LOV) system. The LOV is a newly developed device that is integrated as part of the selection valve of the SIA system.…”