Speciation of iron in river and tap waters by catalytic spectrophotometry using oxidation of o-phenylenediamine with hydrogen peroxide

Kawakubo, Susumu; Hagihara, Yuki; Honda, Yukiko; Iwatsuki, Masaaki

doi:10.1016/s0003-2670(99)00076-8

Cited by 28 publications

(35 citation statements)

References 15 publications

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“…Fe(II) and Fe(III) were determined as Fe(III) by the methods, because of the oxidation of Fe(II) with H2O2. 3 In the FIA method, the sampling rate (8 samples h -1 ) for non-acidified samples was lower than that for acidified samples (1 mmol L -1 HCl), because of the longer tailing of the peak profile, as shown in Fig. 3 (B).…”

Section: Determination Characteristicsmentioning

confidence: 94%

“…3 Therefore, when the dissolution of the adsorbed iron(III) hydroxide(s) is negligible, the adsorption does not cause any determination error for reactive iron in the proposed catalytic FIA. Figure 3 (B) shows the peak profiles measured by catalytic FIA.…”

Section: Adsorption Of Iron In the Fia Systemmentioning

confidence: 96%

“…3 For FIA, a fixed time method (the measurement of the peak height) was adopted and the reaction condition was optimized for rapid analysis, based on a study 3 by the manual-batch method. Figure 2 (A) shows the effect of the reaction temperature on the peak height of 20 µg L -1 of Fe(III) and the sampling rate (samples h -1 ).…”

Section: Optimization Of the Fia Systemmentioning

confidence: 99%

“…The standard deviation (s) in five determinations of 2 µg L -1 of Fe(III) was used to estimate the detection limit (DL) of iron corresponding to 3s. The determination characteristics of the FIA method were compared with the previous manual-batch method, 3 and are summarized in Table 1. The DL value obtained by the FIA method was equal to that by the manual-batch method.…”

Section: Determination Characteristicsmentioning

confidence: 99%

“…3 Characterization was also required for the proposed FIA method, because the reaction conditions were different in both the methods and a significant adsorption of iron(III) hydroxide on the PTFE tube was caused in the FIA system. The abundances of reactive iron determined by the proposed FIA method were compared with the calculated values 3 based on the chemical equilibrium of the iron complexes using the stability constants at 25˚C (ion strength, 0). Oxalato and fluoro complexes.…”

Section: Characterization Of Reactive Iron Speciesmentioning

confidence: 99%

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Catalytic Flow-Injection Determination of Reactive Iron in Non-Acidified Water Samples

2003

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The speciation of reactive metallic species is important in environmental and biological studies, because their bioavailability and toxicity depends on the reactivity or lability of the species. 1 Our previous studies revealed the usefulness of catalytic methods for the speciation of reactive vanadium, 2 iron 3-5 and molybdenum 6 species in natural water. Especially, the catalytic spectrophotometric method 3 using an ironcatalyzed oxidation reaction of o-phenylenediamine (OPDA) with hydrogen peroxide can be used to determine reactive iron with well-characterized forms, i.e., Fe 3+ and Fe III Li 3-in , where i = 1 or 2 for a unidentate ligand and i = 1 for a bidentate ligand (L n-), as naturally occurring species in water samples without any chemical pretreatment. The water sample is usually acidified before analysis. However, acidification should be avoided for speciation, because it changes the chemical forms of iron, e.g., the dissociation of unreactive iron(III) hydroxide(s) and complexed iron species. 4,5 Flow injection analysis (FIA) is suitable for the catalytic method, because of easy and precise control of the kinetic processes of a micro volume of the sample. PTFE tubes are most commonly used for the manifold of the FIA system. However, iron in a neutral or basic solution is adsorbed on the inner wall of the PTFE tube, although adsorption can be used for the preconcetration of iron. 7 The inhibition of adsorption with magnesium(II) was reported, 7,8 but was insufficient for iron. Therefore, we studied the influence of the adsorption of iron, and developed its evaluation method for a reliable FIA using the above-mentioned catalytic reaction. The reactive form of iron was characterized by an equilibrium study of hydroxo, fluoro and oxalato Fe(III) complexes. The proposed FIA method was applied to the speciation of reactive and unreactive iron in river-and tap-water samples. Experimental ReagentsUnless stated otherwise, all chemicals were of analyticalreagent grade. Ultrapure water with ≥ 18 MΩ m and Ultrapur HCl and NaOH solutions (high-purity reagents, Kanto Chemical) were used throughout. An OPDA solution (60 mM) was prepared by dissolving the reagent in water. This solution was stored in a refrigerator at 5˚C and used within 12 h. An iron stock standard solution (1.00 g L -1 of Fe(III)) was prepared by dissolving FeNH4(SO4)2·12H2O (purity ≥ 99.0%) in 0.1 mol L -1 HCl. Working iron standard solutions containing 1 mM HCl were prepared by diluting the stock standard solution with 1 mM HCl before use. Iron solutions with higher pH values (> 3) were prepared by adding 0.1 mM NaOH into the working iron standard solution, diluting with water, and used after equilibrating for 24 h at 25˚C in polystyrene bottles. In a complexation study, the working iron solution was mixed with a Na2C2O4 or NaF solution at pH 3 just before the determination. If necessary, the iron concentrations in these solutions were determined by atomic-absorption spectrophotometry (AAS) after acidification to 0.1 mol L -1 HCl. Humic acid (H...

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Section: Determination Characteristicsmentioning

confidence: 94%

Section: Adsorption Of Iron In the Fia Systemmentioning

confidence: 96%

Section: Optimization Of the Fia Systemmentioning

confidence: 99%

Section: Determination Characteristicsmentioning

confidence: 99%

Section: Characterization Of Reactive Iron Speciesmentioning

confidence: 99%

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Catalytic Flow-Injection Determination of Reactive Iron in Non-Acidified Water Samples

2003

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Effect of cationic impurities on solubility and crystal growth processes of ammonium oxalate monohydrate: Role of formation of metal‐oxalate complexes

Sangwal

Mielniczek‐Brzóska

2007

Cryst. Res. Technol.

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The effect of different bi-and trivalent cationic impurities on the solubility of ammonium oxalate and the composition and distribution of chemical complexes formed in saturated ammonium oxalate aqueous solutions as a function of impurity concentration are investigated. The knowledge of the composition and stability of complexes formed in saturated aqueous solutions is then employed to explain the appearance of dead zones of supersaturation for growth and the difference in the effective segregation coefficient of the impurities. Analysis of the experimental results revealed that: (1) at a constant temperature, the dependence of concentration of complex species formed in saturated solutions on the concentration of different impurities can be described by an equation similar to that of the concentration dependence of density of solutions, (2) the dominant metal-containing species present in saturated solutions are negatively-charged, most stable oxalato complexes like Cu(C 2 O 4 ) 2 2− , Mn(C 2 O 4 ) 3 4− , Zn(C 2 O 4 ) 3 4− , Cr(C 2 O 4 ) 3 3− and Fe(C 2 O 4 ) 3 3− , (3) in the investigated range of impurity concentration, the solubility of ammonium oxalates increases linearly with the concentration of all impurities and the increase is associated with the stability of dominant complexes, (4) appearance of dead supersaturation zones in the presence of impurities is associated with instantaneous adsorption of all growth sites by dominant oxalato complexes in relatively short adsorption time, and (5) the segregation coefficient of an impurity cation M of charge z+ increases with a decrease in the solubility product constant K sp for the hydrolysis products of reactions of the type: M z+ ↔ M 1 (z-1)+ + H + (where the cation M has z+ charge, and H + is hydrogen ion).

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Ultrasound Assisted Emulsification Microextraction Based on dimetyl (E)‐2‐[(Z)‐1‐acetyl)‐2‐hydroxy‐1‐propenyl]‐2‐butenedioate for Determination of Total Amount of Iron in Water and Tea Samples

Khayatian

Hassanpoor

2012

J Chinese Chemical Soc

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An ultrasound assisted emulsification microextraction (USAEME) is successfully used for extraction and determination of trace amount of iron in water and tea samples, followed by flame atomic absorption spectroscopy (FAAS). In this approach, a new synthetic ligand dimetyl (E)-2-[(Z)-1-acetyl)-2-hydroxy-1-propenyl]-2-butenedioate (DAHPB) is used as chelating agent and chloroform is selected as an extraction solvent. The factors influencing the complex formation and extraction by USAEME method are optimized. These factors are extraction solvent type as well as extraction volume, time, temperature, pH, and the amount of chelating agent. Under optimum conditions, an enrichment factor of 202.9 is obtained from only 7.1 mL of aqueous phase. The calibration graph using the preconcentration system for iron is linear between 40.0 and 800.0 mg L -1 with a detection limit of 7.4 mg L -1 . The relative standard deviation (R.S.D) for ten replicate measurements of 500.0 mg L -1 of iron is 2.5%. Article Khayatian and Hassanpoor Scheme IDimetyl (E)-2-[(Z)-1-acetyl)-2-hydroxy-1-propenyl]-2-butenedioate (DAHPB)

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Speciation of iron in river and tap waters by catalytic spectrophotometry using oxidation of o-phenylenediamine with hydrogen peroxide

Cited by 28 publications

References 15 publications

Catalytic Flow-Injection Determination of Reactive Iron in Non-Acidified Water Samples

Catalytic Flow-Injection Determination of Reactive Iron in Non-Acidified Water Samples

Effect of cationic impurities on solubility and crystal growth processes of ammonium oxalate monohydrate: Role of formation of metal‐oxalate complexes

Ultrasound Assisted Emulsification Microextraction Based on dimetyl (E)‐2‐[(Z)‐1‐acetyl)‐2‐hydroxy‐1‐propenyl]‐2‐butenedioate for Determination of Total Amount of Iron in Water and Tea Samples

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