Automated Monosegmented Flow Analyser. Determination of Glucose, Creatinine and Urea

Raimundo, Ivo M.

doi:10.1039/a702750h

Cited by 42 publications

(12 citation statements)

References 29 publications

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“…The 10.00 mg l ¡1 Cr(VI) standard solution was injected by employing loop L5 while the water sample was injected through loops L3 and L4 (® gure 1b). After the injection of the monosegment into the reaction coil, the sulphuric acid and diphenylcarbazide reagents were added to the sample at a¯ow rate of 0.07 and 0.05 ml min ¡1 , respectively, by employing an automatic reagent addition module described elsewhere [53]. Absorbance measurements were carried out at 540 nm.…”

Section: Methodsmentioning

confidence: 99%

“…However, as loops L3 and L4 are for sample and loop L5 is for the Cr(VI) reference solution, that is, the reverse of the titration procedure, the A i and A s absorbance s are also obtained by ® lling these loops with KMnO 4 and water in an inverse manner. Furthermore, to obtain A 0 , A i and A s values, water is added to the monosegment through the automatic reagent addition module [53] at the same¯ow rate as reagents are added to the sample during the analysis.…”

Section: Calibration Of the Systemmentioning

confidence: 99%

“…The monosegmented¯ow analyser employed here has been described elsewhere [53]. A home-made diodearray spectrophotomete r was employed as detector [54].…”

Section: Monosegmented £Ow Manifoldmentioning

confidence: 99%

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

Raimundo¹

2001

Journal of Automated Methods & Management in Chemistry

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An automated system to perform titration and standard addition in monosegemented £ow analysis by employing the simultaneous multiple injection is described. The system was controlled by a PC-AT-386 microcomputer through a home-made parallel interface, employing a diode array spectrophotometer as detector. Software was written in QuickBasic 4.5 to control the system and for data acquisition. A three-way solenoid valve was used in conjunction with a proportional injector to add the titrant solution or the standard solution to the sample, to carry out titration or standard addition, respectively. Only one standard solution was used in each procedure and di¡erent quantities of titrant or standard were added to the sample by controlling the time interval in which the solenoid valve was switched on. Titration and standard addition curves similar to those of the manual methods were obtained in both cases, since the sample dispersion was very low due to the air bubbles of the monosegment. The titration system was evaluated through the determination of Fe(II) with a KMnO 4 standard solution in pharmaceutical preparations. The standard addition process was assessed by determining Cr(VI) in natural waters and domestic wastewater using the diphenylcarbazide method. The results obtained in both methodologies did not di¡er signi¢cantly from the reference methods at a 95% con¢dence level.

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Section: Methodsmentioning

confidence: 99%

Section: Calibration Of the Systemmentioning

confidence: 99%

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

Raimundo¹

2001

Journal of Automated Methods & Management in Chemistry

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“…The monosegmented system generates the flow pattern, in Figure 4B, after a single movement of the sample introduction device. Immediately after introduction, the central liquid monosegment does not contain the reagent which is added further in the manifold 24 . As the material employed for the manifold construction is glass (a hydrophilic material) a thin film of the reagent solution is produced on the wall of the tube manifold.…”

Section: Monosegmented and Bisegmented Flow Systemsmentioning

confidence: 99%

Determination of Gaseous Analytes in Flow Systems: A Review

Pasquini¹,

Silva²

1999

J. Braz. Chem. Soc.

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Uma revisão crítica dos trabalhos visando a aplicação de sistemas de análises químicas em fluxo à determinação de analitos gasosos em amostras gasosas é apresentada. Os sistemas em fluxo constituem em uma alternativa apropriada para manipulação e processamento de amostras gasosas sendo, no entanto, encontrados na literatura um número relativamente pequeno de trabalhos relacionados a este assunto. Por outro lado, o advento de sistemas automatizados utilizando microcomputadores e de novos dispositivos, tais como válvulas solenóides miniaturizadas, as quais facilitam a manipulação das amostras gasosas, o fácil acesso a padrões gasosos, e o aumento da demanda por determinações de analitos gasosos, têm contribuído para o recente progresso associado ao uso de sistemas em fluxo. Pode-se concluir que os sistemas em fluxo constituem uma opção rápida, versátil, capaz de ser aplicada a uma ampla faixa de concentração, de fácil operação com consumo de amostra relativamente pequeno, constituindo-se em uma alternativa de baixo custo para determinação de analitos gasosos.Efforts to develop flow systems for the determination of gaseous analytes in gaseous samples are critically reviewed. Although flow systems present a suitable alternative to management and processing of gaseous samples, relatively few papers dealing with this subject are found in the literature. The increased demand for determination of gaseous analytes, the advent of automated systems based on microcomputers and new devices, such as miniature solenoid valves, which facilitate manipulation of gaseous samples, and the easy access to gaseous standards has, along, driven some recent progress towards the use of flow systems. Flow systems constitute a versatile option capable to be applied to a wide concentration range, rapid, easy to operate with relatively low sample volume, becoming a low cost approach for determination of gaseous analytes.

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“…The approach has been exploited mainly for improving the sensitivity and/or sampling rate. [2][3][4][5][6][7][8][9] The sample is inserted into the carrier stream between two air bubbles and, as a consequence, its integrity is maintained and the wash period reduced. A sample compartment is then formed and preserved, inside of which vortices are established.…”

mentioning

confidence: 99%

A Monosegmented Flow Titration for the Spectrophotometric Determination of Total Acidity in Vinegar

et al. 1999

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Monosegmented flow systems were conceived by Pasquini and Oliveira 1 as a means to attain a long sample resident time without pronounced dispersion. The approach has been exploited mainly for improving the sensitivity and/or sampling rate. [2][3][4][5][6][7][8][9] The sample is inserted into the carrier stream between two air bubbles and, as a consequence, its integrity is maintained and the wash period reduced. A sample compartment is then formed and preserved, inside of which vortices are established.10 This compartment may act as a titration vessel with efficient stirring when the sample and titrant (plus indicator) are sequentially inserted to constitute a tandem plug between the air bubbles. A mixing chamber in the analytical path is then not required and a washing step is efficiently accomplished. This feature becomes particularly attractive for flow titrations that do not require analytical curves. [11][12][13][14] Classical titrations are based on the sample-to-titrant volumetric ratios and stoichiometry, whereas flow titrations usually require calibration curves involving analytical solutions. [15][16][17][18][19][20][21][22][23][24][25] For some applications, however, the preparation of the analytical solutions becomes cumbersome. This may become a limiting factor in situations of a pronounced matrix effect when matrix matching is not feasible as e.g. in the analysis of molasses. Moreover, the results may depend on more than one analyte, and different analytes may present different reaction stoichiometries towards the titrant.To circumvent this drawback, Araújo and co-workers 26 developed a flow titrator exploiting calibration of the concentration gradient generated after sample injection into a diluent carrier stream. Analytical solutions were not required, but the dispersion of the sample should be identical to that of the solution used for a previous gradient calibration. Although other flow systems that did not require analytical curves have been proposed [11][12][13][14] , the sample and/or titrant had to be injected several times after proper volume variations, and the sample throughput was very dependent on the washing period. This period undergoes a reduction with monosegmentation.The feasibility of a monosegmented tandem flow system to perform automatic flow titrations was demonstrated in the present work. As an application, a spectrophotometric determination of vinegar acidity using NaOH and phenolphthalein as the titrant and as the indicator was selected. The end point search was based on the one-dimensional optimization method of Fibonacci 27 , which was recently adapted for fast titrations. 14 The algorithm always minimizes the initial interval of uncertainty related to the titrant volume, which contains the optimized value (volume at the equivalence point). After successive reduction steps, the interval converges to a very narrow one, the final interval of uncertainty which corresponds to the titrant volume at the equivalence point plus its uncertainty. A monosegmented flow system involvi...

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Automated Monosegmented Flow Analyser. Determination of Glucose, Creatinine and Urea

Cited by 42 publications

References 29 publications

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

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

Determination of Gaseous Analytes in Flow Systems: A Review

A Monosegmented Flow Titration for the Spectrophotometric Determination of Total Acidity in Vinegar

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