Repetitive determinations of iron(iii) in closed flow-through systems by series reactions

Dutt, V. V. S. Eswara; Scheeler, Daniel; Mottola, Horacio A.

doi:10.1016/s0003-2670(01)84529-3

Cited by 11 publications

(3 citation statements)

References 15 publications

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“…Therefore, elimination of the accumulated reaction products and regeneration of the main reagent are required to maintain a long-running flow system. Some reports have been published concerning cyclic FIA using kinetic (reaction rate) methods [1][2][3][4] or the skillful application of electrolysis for removing metal ions. 5,6 Other reports include the incorporation of an immobilized enzyme column for its effective use.…”

Section: Introductionmentioning

confidence: 99%

Cyclic Flow-Injection Analysis for the Repetitive Determination of Zinc with 2-(5-Bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol and EDTA

et al. 2005

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Cyclic methods of analysis can lead to many advantages, such as low consumption of reagents, minimization of waste, high sample throughput, simple equipment, extended running hours and no contamination of the environment. Flow-injection analysis (FIA) is considered to be a most suitable technique for cyclic methods, i.e., the outlet from the flow-through cell is fed continuously back to the reservoir using a single-line flow system. On this cyclic FIA, the chemical reaction can be easily controlled by fixing the flow rate of a circulating reagent carrier solution and by the constant introduction of a sample solution to the carrier stream. Reproducible mixing of the sample and the reagents can be achieved within the closed flow system, resulting in a highly precise and reproducible signal response. Since the reaction products accumulate in the circulated flow system, a gradual built-up of the background signal produces a continuous baseline shift that limits the useful detection scale. Therefore, elimination of the accumulated reaction products and regeneration of the main reagent are required to maintain a long-running flow system. Some reports have been published concerning cyclic FIA using kinetic (reaction rate) methods 1-4 or the skillful application of electrolysis for removing metal ions. 5,6 Other reports include the incorporation of an immobilized enzyme column for its effective use. The high cost of enzymes justifies attempts to regenerate and reuse them in the system. [7][8][9][10][11] Among the analytical methods, although spectrophotometry is the most commonly used in FIA, there appears to be little in the literature concerning cyclic FIA with spectrophotometric detection. To reuse chromogenic reagents effectively, a rapid regeneration system for them is desired under circulating flow conditions.In a rapid communication, 12 we have proposed a new concept to eliminate the reaction products in a cyclic FIA system. The adoption of a complexing agent (inhibitor) together with a chromogenic reagent makes it possible to regenerate and reuse the main reagent repeatedly. To recognize the new concept and to further test its applicability, a cyclic FIA system has been proposed for the determination of zinc. In order to improve the manipulation and the sensitivity, a water-soluble pyridylazo derivative, 2-(5-bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol (5-Br-PAPS), 13-17 is used as a chromogenic reagent. Hayashibe et al. 18 have shown that 5-Br-PAPS is a selective and sensitive reagent for zinc (ε = 1.4 × 10 5 dm 3 mol -1 cm -1 , at 554 nm), and successfully applied it to the determination of zinc in serum using conventional FIA without any preconcentration or separation procedure. The aim of the work described here is a cyclic FIA system for the repetitive determination and/or monitoring of zinc using 5-Br-PAPS and EDTA by spectrophotometry. Experimental ReagentsAll chemicals used were of analytical-reagent grade, and water was purified in a Millipore Milli-Q system. A zinc standard solution...

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Section: Introductionmentioning

confidence: 99%

Cyclic Flow-Injection Analysis for the Repetitive Determination of Zinc with 2-(5-Bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol and EDTA

et al. 2005

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“…A promising approach for better utilizing the reagent solution is the application of the circulatory (closed-loop) flow injection analysis method (CFIA), which is more suited to the concept of Zero Emission Research Initiative. 6 Dutt and Mottola, 7,8 in pioneering work, reported on the use of CFIA in the determination of chrominum(VI) by recycling a reagent solution of Fe(II)-1,10-phenanthroline complex, where oxalic acid was added to the reagent solution as an accelerator of the redox reaction between Cr(VI) and the complex and regenerator to the Fe(II)-1,10-phenanthroline complex. Ishii et al 9,10 and Zenki et al, [11][12][13][14] respectively, reported on CFIA/chemiluminescent and CFIA/spectrophotometric methods in which a reagent solution is circulated and regenerated by the reaction of the product with a component added to the reagent solution as an inhibitor.…”

Section: Introductionmentioning

confidence: 99%

Potentiometric Determination of Bromate Using an Fe(III)-Fe(II) Potential Buffer by Circulatory Flow-Injection Analysis

et al. 2004

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“…There appears to be little in the literature concerning repeated use of the reagent solution. [1][2][3][4][5][6][7][8] In industrial quality control and environmental monitoring, a large number of samples of similar nature must be analyzed for determining of a single species. A method which is rapid, repetitive, accurate, easily handled and with low cost is required.…”

Section: Introductionmentioning

confidence: 99%

Repetitive Determination of Calcium Ion and Regeneration of a Chromogenic Reagent Using Chlorophosphonazo III and an Ion Exchanger in a Circulatory Flow Injection System

2002

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The spectrophotometric determination of Ca 2+ with chlorophosphonazo III (CPN) has been carried out by a circulatory flow injection (FI) method. A cation-exchange mini-column for the on-line regeneration of the main reagent was incorporated in this FI system, allowing a repetitive determination of Ca 2+ . A solution of 4.0 × 10 -5 M CPN in a 0.05 M acetate buffer (pH 5.0) in a single reservoir (50 ml) was continuously circulated at a constant flow rate of 1.5 ml min -1 . Into the stream, an aliquot (20 µl) of a sample containing Ca 2+ was quickly injected by means of a 6-way valve. The complex formed was monitored spectrophotometrically at 670 nm in the flow system. Then, the stream passed through a cation-exchange column, which was introduced after the flow-through cell. A successful ligand-exchange reaction of Ca 2+ between the CPN reagent and a cation exchanger, as well as a simultaneous regeneration of the free reagent took place. The stream then returned to the reservoir. The regeneration and recycling of the CPN reagent allowed as many as 300 repetitive determinations of 2.5 mg l -1 Ca 2+ solutions with the same 50 ml circulating solution.

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Repetitive determinations of iron(iii) in closed flow-through systems by series reactions

Cited by 11 publications

References 15 publications

Cyclic Flow-Injection Analysis for the Repetitive Determination of Zinc with 2-(5-Bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol and EDTA

Cyclic Flow-Injection Analysis for the Repetitive Determination of Zinc with 2-(5-Bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol and EDTA

Potentiometric Determination of Bromate Using an Fe(III)-Fe(II) Potential Buffer by Circulatory Flow-Injection Analysis

Repetitive Determination of Calcium Ion and Regeneration of a Chromogenic Reagent Using Chlorophosphonazo III and an Ion Exchanger in a Circulatory Flow Injection System

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