Simultaneous multiple injection to perform titration and standard addition in mono‐segmented flow analysis

Assali, Margarete; Raimundo, Ivo M.; Facchin, Ileana

doi:10.1155/s1463924601000104

Cited by 14 publications

(11 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The analytical performance of the proposed system is comparable to monosegmented titrators described in the literature, 22,23,[25][26][27] presenting an advantage when compared with ordinary sequential injection analysis titration systems, 15-17 since it does not need a calibration step with standard solutions. Table 2.…”

Section: Resultsmentioning

confidence: 77%

“…The precision for determination of the end point (stop condition) was set in 1.0%, providing sample throughputs of eight and ten samples hour -1 for milk and wine, respectively. The lower analytical frequency for milk is due to coagulation, which takes place when the nitric acid is added, requiring a longer reaction coil to provide a proper mixing of sample and titrant.The analytical performance of the proposed system is comparable to monosegmented titrators described in the literature, 22,23,[25][26][27] presenting an advantage when compared with ordinary sequential injection analysis titration systems, 15-17 since it does not need a calibration step with standard solutions. Table 2.…”

mentioning

confidence: 77%

“…Aquino et al 22 have proposed an automatic monosegmented flow titrator, which can perform a true titration according to the IUPAC definition, by employing a single aliquot of sample. Assali et al 23 have employed the simultaneous multiple injection concept 24 to implement a spectrophotometric titration in a monosegmented system. Although a titration curve with a shape similar to that of manual titration is obtained, several injections of sample and titrant must be made in order to obtain the curve; the concentration of the analyte can be straightforwardly determined by knowing the volumes of the injected solutions.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Vieira¹,

Raimundo²,

Reis³

et al. 2003

J. Braz. Chem. Soc.

View full text Add to dashboard Cite

Este trabalho descreve um procedimento automático em fluxo monossegmentado para titulação potenciométrica aplicado à determinação de cloreto em leite e vinho. O sistema de fluxo foi desenvolvido com base em uma válvula solenóide de 6 vias, controlada por um microcomputador através de um programa escrito em VisualBasic 3.0. Um eletrodo indicador tubular de Ag 2 S seletivo a Cl -e um eletrodo de referência convencional de Ag/AgCl foram empregados. Um algoritmo baseado na diferença de potencial entre duas adições subsequentes de titulante foi desenvolvido, possibilitando a determinação do ponto final da titulação em, no máximo, 10 tentativas, com uma precisão melhor que 1,0%. O sistema proposto foi avaliado pela determinação de cloreto em leite e vinho, usando uma solução padrão de AgNO 3 como titulante. A exatidão foi avaliada comparando-se os resultados com aqueles obtidos pelo método da AOAC, não sendo encontradas diferenças significativas ao nível de confiança de 95%.An automated flow potentiometric titration procedure for the determination of chloride in milk and wine exploiting the monosegmented flow approach is described. The flow network was designed based on a six-way solenoid valve, controlled by a microcomputer running software written in VisualBasic 3.0, allowing selection of the titration conditions. An Ag 2 S tubular electrode selective for Cl -and a conventional Ag/AgCl electrode were employed as indicator and reference, respectively. An algorithm based on the potential difference between two subsequent titrant additions was developed, allowing to reach the end point in less than 10 attempts, with a precision better than 1.0%. The proposed system was evaluated by determining chloride in milk and wine, using a standard AgNO 3 solution as titrant. Accuracy was ascertained by comparing the results with those obtained using the AOAC procedure. No significant difference at a 95% confidence level was observed.Keywords: potentiometric titration, monossegmented flow, multicommutation, ion selective electrode, chloride in milk, chloride in wine IntroductionThe mechanisation of the potentiometric titration procedure was first described in 1914 1 and the introduction of flow injection analysis in 1975 2 improved this mechanisation, including for potentiometric and spectrophotometric titrations. [3][4][5] Flow injection titration usually employs a calibration step, in which the peak width (instead of height) is taken as the analytical parameter. The simplest approach, which was first proposed by Ruzicka et al. 6 in 1977, employs a single line manifold and is still being employed nowadays. 7,8 Different alternatives have been proposed to determine the stoichiometric point in a flow titration procedure. Continuous flow systems based on the ratio of sample and titrant flow rates have been exploited to achieve the end point. 9,10 In order to vary the flow rates of the solutions independently, two peristaltic pumps are necessary, which 260 Vieira et al. J. Braz. Chem. Soc. represents the main drawback of these...

show abstract

Section: Resultsmentioning

confidence: 77%

mentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Vieira¹,

Raimundo²,

Reis³

et al. 2003

J. Braz. Chem. Soc.

View full text Add to dashboard Cite

show abstract

“…Monosegmented flow titration is characterized by the formation of segments of liquid-each segment consists of the sample, titrant, and possibly a diluent-separated on both sides from the carrier by a segment of air (or inert gas) [21][22][23][24][25][26][27][28]. The components of the created monosegment are mixed in a reaction coil.…”

Section: Introductionmentioning

confidence: 99%

Novel Approach to Automated Flow Titration for the Determination of Fe(III)

et al. 2020

View full text Add to dashboard Cite

A novel approach to automated flow titration with spectrophotometric detection for the determination of Fe(III) is presented. The approach is based on the possibility of strict and simultaneous control of the flow rates of sample and titrant streams over time. It consists of creating different but precisely defined concentration gradients of titrant and analyte in each successively formed monosegments, and is based on using the calculated titrant dilution factor. The procedure was verified by complexometric titration of Fe(III) in the form of a complex with sulfosalicylic acid, using EDTA as a titrant. Fe(III) and Fe(II) (after oxidation to Fe(III) with the use of H2O2) were determined with good precision (CV lower than 1.7%, n = 6) and accuracy ( | RE | lower than 3.3%). The approach was applied to determine Fe(III) and Fe(II) in artesian water samples. Results of determinations were consistent with values obtained using the ICP–OES reference method. Using the procedure, it was possible to perform titration in 6 min for a wide range of analyte concentrations, using 2.4 mL of both sample and titrant.

show abstract

“…Such problems have been circumvented by using automated flow systems. [7][8][9][10][11][12][13][14][15][16][17][18][19] Versatile and flexible flow-batch approaches [20][21][22][23] have been proposed to automate some analytical systems, as developed by our research group. The flow-batch systems use three-way solenoids valves and an open mixing chamber and are characterised to combine the intrinsic favorable features of both the flow and batch techniques and to provide very good analytical figures of merit.…”

Section: Introductionmentioning

confidence: 99%

An automatic flow-batch standard-addition method for sodium determination in alcohol fuel by flame photometry

Almeida¹,

Martins²,

Silva³

et al. 2003

J. Braz. Chem. Soc.

View full text Add to dashboard Cite

A agência brasileira que regulamenta a produção e comercialização de álcool combustível estabelece que a concentração de sódio deve ser determinada usando a fotometria de chama e curva analítica construída com soluções padrão preparadas em uma matriz que se assemelhe às amostras. Todavia, essa metodologia pode produzir resultados inexatos porque o álcool combustível apresenta uma variabilidade significativa na composição de matriz e, conseqüentemente, no efeito de matriz. Esse problema pode ser contornado usando o método por adições de padrão (MAP), porém o MAP é lento e trabalhoso quando realizado manualmente. Para superar esses inconvenientes, um sistema Flow-Batch é proposto para automatizar o MAP visando à determinação de sódio em álcool combustível por fotometria de chama. O sistema requer uma única solução padrão, processa cerca de 80 -140 amostras por hora, consome um volume total de amostra e solução padrão menor que 1,5 mL por análise e apresenta um desvio padrão usualmente menor que 0,1 mg L -1 (n = 4).The Brazilian Regulatory Agency for fuel production and commercialization requires that the sodium concentration in alcohol fuel should be determined by flame photometry and that the analytical curves should be obtained with matrix-matched standards. Notwithstanding, this methodology can produce inexact results because alcohol fuel presents a significant variability in matrix composition and, consequently, in the matrix effect. This problem can be circumvented by using the standard addition method (SAM). However, this method is slow and laborious when it carried out by manual procedures. To overcome these drawbacks, an automatic flow-batch SAM for sodium determination in alcohol fuel by flame photometry is described. This system requires only one standard solution, handles about 80 -140 samples per hour and consumes a total volume of sample and of standard solution smaller than 1.5 mL for each analysis. The results present a standard deviation usually less than 0.1 mg L -1 (n = 4).Keywords: standard-addition method, flow-batch system, sodium determination, alcohol fuel, flame photometry IntroductionThe Brazilian Regulatory Agency for fuel production and commercialization, the National Agency for Petroleum Products (ANP), requires 1 that sodium concentration in alcohol fuel samples should not be higher 2 mg kg -1 and that sodium should be determined by using the methodology (NBR 10422) 2 described by the Brazilian Normative Agency (Associação Brasileira de Normas Técnicas, ABNT).The ABNT methodology for sodium determination in alcohol fuel uses flame photometry and an analytical curve with matrix-matched standards (ACMMS). 3 Since the composition or matrix effect of actual alcohol fuel samples varies significantly, this methodology can produce inexact results. 3,4 To overcome this problem, the standard-addition method (SAM) 5 should be used to accurately analyse each sample.One of the ways to implement SAM 5 is to add increasing amounts of analyte to identical aliquots of the sample; these mixtures are th...

show abstract

Simultaneous multiple injection to perform titration and standard addition in mono‐segmented flow analysis

Cited by 14 publications

References 8 publications

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

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

Novel Approach to Automated Flow Titration for the Determination of Fe(III)

An automatic flow-batch standard-addition method for sodium determination in alcohol fuel by flame photometry

Contact Info

Product

Resources

About