Continuous-flow determination of manganese in natural waters containing iron

A re-evaluation of the use of formaldoxime to determine manganese in natural waters at concentrations of 0–100 μM is reported. Addition of EDTA after formation of the manganese/formaldoxime complex removes interference from up to 100 μM iron. The extents of formation and destruction of the iron and manganese complexes with formaldoxime depend on the pH of the solution and on the time between reagent addition and measurement of absorbance.     

Identical flow injection spectrophotometric manifold for determination of protein, phosphorus, calcium, chloride, copper, manganese, iron, and zinc in feeds or premixes

A simple procedure using an identical manifold was developed for determination of nitrogen (protein) phosphorus, calcium, chloride, copper, manganese, iron, and zinc in feeds and feedstuffs. By changing appropriate reagents and detection wavelength, these 8 elements were determined successively with a simple identical double-line flow injection (FI) manifold. Fl spectrophotometric determinations were made by the blue indophenol reaction for ammonium, the molybdenum blue method for phosphate, the cresolphthalein complexone procedure for calcium, and the mercuric thiocyanate procedure for chloride. The chromogenic reagents for copper, iron, manganese, and zinc determination were bis(cyclohexanone)oxalydihydrazone (Cuprizone), 1,10-phenanthroline, formaldoxime, and xylenol orange, respectively. Sample digestion catalyst, Fl manifold, and some chemical parameters were optimized. The proposed procedure had a sampling rate of 90/h for each analyte. The determination ranges (mg/L) were 10-60 for N, 1-15 for P and Ca, 540 for Cl, and 0.5-15 for Cu, Fe, Mn, and Zn, respectively. Results of the analyses of animal feed and feedstuff samples by this procedure did not differ significantly from those obtained by proven manual methods.     

Dosage spectrophotometrique de differents metaux (Mn,Ce, V,Ni, Fe) au moyen de la formaldoxime

Formaldoxime forms highly coloured complexes (? = 4000–18000) with manganese, cerium, vanadium, nickel and iron in alkaline media. On the basis of a study of reaction mechanisms and of the optimum conditions for the formation of the different complexes, new spectrophotometric methods are described for determination of cerium and iron, as well as improved methods for determination of manganese, nickel and vanadium. The use of formaldoxime for Mn, Ce and V is particularly beneficial in trace analysis and the methods suggested are specific.     

Analytical use of the selective extraction of copper as its phenylacetate

Chloroform solution of phenylacetic add has been found very suitable for extraction and colorimetric determination of copper. Iron and uranium are the main interferences, which can be overcome by masking with ammonium fluoridc. Under these conditions, only gold(III), platinum(IV) and palladium(II) are co-extracted, but their colour does not interfere with measurement of the green copper extract at 700 nm. The method has been applied to the determination of copper in iron, steels, uranium, lead concentrates and alloys containing nickel, cobalt, etc. The extraction procedure can also be used to remove interference of iron, copper and uranium in the determination of manganese with formaldoxime.     

Flow injection spectrophotometric determination of copper, iron, manganese, and zinc in animal feeds using a common manifold

A rapid and simple procedure was developed for the determination of copper, iron, manganese, and zinc in animal feeds using an identical flow injection spectrophotometric manifold but different chromogenic reagents and different detection wavelengths. Bis(cyclohexanone)oxalydihydrazone, formaldoxime, 1,10-phenanthroline, and xylenol orange were adopted as chromogenic reagents for Cu, Mn, Fe, and Zn, respectively. Detection conditions such as manifold parameters, buffer pH, reagent concentration, temperature, and acidity of sample solution were optimized. Analytical characteristics of the method and interference of metal ions commonly present in feeds were studied. By changing the reagents and detection wavelengths, which can be done quickly, the proposed low cost flow injection system can determine Cu, Fe, Mn, or Zn in the range of 0.5-10 mg/L with a sampling throughput of 120/h.     

Spectrophotometric determination of hydroxylamine alone and in the presence of monochloramine

Hydroxylamine (< 3 × 10^?3 mol l^?1) is quantified by ultraviolet spectrophotometry after reaction with an excess of formaldehyde in buffered solution at pH 12.2. The absorbance of the formaldoxime produced is measured at 218 nm (? = 5480 l mol^?1 cm^?1) when hydroxylamine is alone but at 230 nm (? = 3230 l mol^?1 cm^?1) when monochloramine is present.     

A double-line sequential injection system for the spectrophotometric determination of copper, iron, manganese, and zinc in waters

A double-line sequential injection system was developed for the spectrophotometric determination of several metal ions in waters. The proposed double-line configuration was used to enable adding sample and chromogenic reagents as merging zones. The methodology was applied to the spectrophotometric determination of copper, iron, manganese, and zinc in samples of diverse origins at the range of 0.15-5.00, 0.10-10.0, 0.48-4.00, and 0.11-5.00 mg/L, respectively. Different chromogenic reagents and detection wavelengths were used. The chromogenic reagents for iron and manganese were 1,10-phenanthroline and formaldoxime, respectively. Copper and zinc were both determined using the analytical reagent zincon. Analytical characteristics of the methodology, such as manifold parameters, buffer pH, and reagent concentrations were optimized, and interference of some of the metal ions commonly present in water sample was assessed. Results of the analysis were in agreement with those obtained by atomic absorption spectrometry. Repeatability, expressed as the relative standard deviation for 10 consecutive injections of water samples, was lower than 6%. The determination rate was approximately 36/h.     

Preconcentration of manganese(II) from natural and sea water on a palmitoyl quinolin-8-ol functionalized XAD copolymer resin and spectrophotometric determination with the formaldoxime reagent

A palmitoyl quinolin-8-ol (P.Ox)-functionalized Amberlite XAD-2 copolymer resin (XAD-P.Ox) was used in the column mode to preconcentrate trace Mn(II) from artificial and real seawater, and Mn in the eluate was determined by the formaldoxime (FAD) spectrophotometric method, the results compared with those of FAAS. The optimal pH interval of Mn uptake by the resin was between pH 7 and 10 (best at 8). Other column operation parameters such as adsorption and elution flow rate, and eluent volume were optimized. Since a preconcentration factor of approximately 60 was achieved with the resin column, the detection limits (LOD) of spectrophotometry and FAAS for Mn (i.e. 17 and 12 μg l⁻¹, respectively) were significantly reduced. The most serious interferent to the FAD procedure, i.e. ferric iron, was eliminated using the resin retention-elution procedure. The proposed method of preconcentration and analysis of Mn(II) was not adversely affected from high ionic strength media, rendering the method suitable for Mn determination in seawater.     

Localized charge distributions: VI. Internal rotation in formaldoxime and formic acid

The INDO localized orbital analysis of internal rotation is extended to the hydroxyl rotors in formic acid and formaldoxime. As for previous internal rotation problems, interpretation of the results can be dependent on whether or not the molecular geometry is optimized for each value of the rotational angle. In the case of formaldoxime, choice of molecular geometry can affect the predicted most stable rotamer. Earlier interpretations of barriers to internal rotation in terms of changes in vicinal interference interactions within bonds and lone pairs adjacent to the axial bond also apply to these molecules.     

An ab initio molecular fragment investigation of the electronic and conformational structure of formaldoxime

An ab initio molecular fragment study of formaldoxime is reported and compared with previous semiempirical and conventional ab initio studies.     

Structure électronique et origines des différences d'énergie entre isoméres de rotation: II. La formaldoxime

The semi-empirical CNDO and INDO methods are applied to the analysis of the electronic structure of various conformations of formaldoxime. In qualitative agreement with experimental data, the trans form of the CN-OH group is predicted to be more stable, by some 3 kcal mole^?1, than the cis form; from the stable form, the barrier to internal rotation is predicted to be equal to 4.6 kcal mole^?1. The computed dipole moment (0.36 ± 0.04 Debyes) is in good agreement with the value determined from Stark effect measurements (0.44 Debyes). Finally, bicentric partitioning of the total molecular energy reveals the principal factors that contribute to the shape of the potential curve.     

对三氟甲基肉桂酸的合成

以对三氟甲基苯胺为原料,经重氮化和缩合反应合成了高纯度的对三氟甲基肉桂酸,总收率41.4%。其结构经1H NMR表征。     

Determination of total iron in ground waters and multivitamin tablets using a solid-phase reactor with tiron immobilised on amberlite ion-exchange resin in a flow injection system

A method is described for the flow injection determination of total iron as Fe(III) using a solid-phase reactor containing disodium-1,2-dihydroxybenzene-3,5-disulphonate (tiron) as substrate. The iron(III) reacted with tiron to form a complex which absorbs strongly at 667 nm, where it was measured spectrophotometrically. The system has a linear range of 1 to 50 mg L^–1 with a detection limit of 0.67 mg L^–1. It is suitable for the determination of total iron in multivitamin tablets and iron-rich ground waters, with a relative standard deviation of better than 1.1%. The results obtained compared favourably with the certified values and a standard ICP-AES method.     

The spectrophotometric determination of iron(III) in a flow-injection system with a mixed solvent

A fast and sensitive flow-injection procedure is described for the determination of iron(III). The complexing agent is ammonium diisopropyldithiophosphate in a 1:1 (v/v) isopropanol/water carrier stream. The linear range is 0.05–15 mg 1^?1 iron(III) with a detection limit of 0.01 mg 1^?1 and the injection rate is about 400 h^?1.     

Synthesis of arsenic sorbent by the reaction of magnesium hydroxide with aqueous iron(III) chloride solution

The reaction of magnesium hydroxide with a concentrated aqueous solution of iron(III) chloride yields a mixture of magnesium–iron layered double hydroxide and iron oxide–hydroxide in the akaganeite form. The content of these phases depends on the Mg/Fe atomic ratio in the starting reactant mixture. Iron oxide–hydroxide is the major reaction product at the Mg/Fe atomic ratio in the interval 1.5–1.75, and layered magnesium–iron layered double hydroxide, at Mg/Fe = 3–4. The ability of the synthesized products to take up As(III) from aqueous solutions was studied. These sorbents allow the arsenic concentration to be decreased from 3–5 mg L^–1 to values below MPC (0.01 mg L^–1).     

A quantum-chemical study of the thermodynamic properties of the CNOH<Subscript>3</Subscript> isomers

The B3LYP/6-311++G(3df,3pd) DFT method was used to determine the geometry and vibrational frequencies for the formamide, formaldoxime, nitrosomethane, oxaziridine, and formimide. The potential energy functions of the hindered internal rotations were calculated. The conformers of formaldoxime and formimide were determined. For all the molecules, including the conformers, the thermodynamic characteristics Δ_f H° (298 K), S°(298 K), C _p(298 K), and Δ_f G° (298 K) were determined. The temperature dependences C _p(T) within 298–1500 K were represented in the form of cubic polynomials.     

Determination of total iron in ground waters and multivitamin tablets using a solid-phase reactor with tiron immobilised on amberlite ion-exchange resin in a flow injection system

A method is described for the flow injection determination of total iron as Fe(III) using a solid-phase reactor containing disodium-1,2-dihydroxybenzene-3,5-disulphonate (tiron) as substrate. The iron(III) reacted with tiron to form a complex which absorbs strongly at 667 nm, where it was measured spectrophotometrically. The system has a linear range of 1 to 50 mg L^–1 with a detection limit of 0.67 mg L^–1. It is suitable for the determination of total iron in multivitamin tablets and iron-rich ground waters, with a relative standard deviation of better than 1.1%. The results obtained compared favourably with the certified values and a standard ICP-AES method. Received: 12 November 1997 / Revised: 9 March 1998 / Accepted: 15 March 1998     

The Effect of Iron and Copper as an Essential Nutrient on Mitochondrial Electron Transport System and Lipid Peroxidation in Trichoderma harzianum

Iron and copper are essential nutrients for all living organisms as cofactors of many enzymes and play important roles in electron transport system (ETS) enzymes which have heme and iron–sulfur centers. In the present study, ETS enzymes, namely, succinate dehydrogenase (SDH) and cytochrome c oxidase (COX), activities as well as adenine nucleotides and lipid peroxidation (LPO) levels of eukaryotic model Trichoderma harzianum grown in varied concentrations of iron (0–20 mg/l) and copper (0–25 mg/l) mediums have been examined. SDH and COX activities increased up to 10 mg/l of iron. COX and SDH activities increased significantly up to 15 and 1 mg/l of copper, respectively. ATP and ADP levels showed a positive correlation with SDH activity with respect to iron–copper concentrations. The trends of AMP were similar with those of ATP and ADP for iron concentrations, while AMP levels elevated until 5 mg/l of copper. As an indicative marker of membrane damage, LPO levels increased with iron and copper concentration. In conclusion, iron and copper concentrations are of critical importance on activities of the ETS enzymes besides adenine nucleotides and LPO levels by maintenance of this metal homeostasis.     

Comparison of four chromogenic reagents for the flow-injection determination of aluminum in water

Pyrocatechol violet (PCV), aluminon, eriochrome cyanine R (ECR) and eriochrome cyanine R with cetyltrimethylammonium bromide (ECR/CTA) are compared as chromogenic reagents for the flow-injection determination of aluminium in water. The detection limit of the ECR/CTA method is 1 μg Al 1^?1. The detection limits of the PCV and ECR methods are 5 μg Al 1^?1. The aluminon method is the least sensitive, with a detection limit of 50 μg Al l^?1. Interference from iron, fluoride, phosphate and the acidity of the sample were investigated. The interference from iron is suppressed by hydroxylammonium chloride/1,10-phenanthroline in the PCV and ECR/CTA methods at concentrations less than 5 mg Fe l^?1. In the ECR and aluminon methods, iron <5 mg l^?1) is masked by ascorbic acid. Fluoride at <0.2 mg l^?1 can be tolerated in all methods. The aluminon method can tolerate up to about 500 mg l^?1 in the three other methods. All methods are sensitive to changes in acidity of the samples; the acidity should be 0.08–0.12 M HCl.     

Une nouvelle méthode de dosage colorimétrique de l'oxygène dissous dans l'eau

Résumé Nous avons présenté une nouvelle méthode de dosage colorimétrique de l'oxygène dissous dans l'eau. Cette méthode est basée sur la réaction de la solution décolorée de manganèse-formaldoxime. La réduction de la solution du dérivé manganique de la formaldoxime est exécutée avec succès à l'aide de la poudre de zinc. Les appareils peuvent être construits facilement et tous les réactifs nécessaires sont d'usage courant. La coloration est stable et les matières comme nitrate, nitrite, fer ferreux, matières organiques etc. ne font pas obstacle dans cette méthode.

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Summary A new method is given for the determination of oxygen dissolved in water. This colorimetric method uses the decolorized solution of manganeseformaldoxime. The reduction of the solution of the manganic derivative of formaldoxime is successfully accomplished by means of zinc powder. The apparatus is easily constructed and all the needed reagents are readily available. The color is stable and no interference arises because of the presence of such materials as nitrate, nitrite, iron (II), organic matter, etc.

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Zusammenfassung Eine neue Methode der kolorimetrischen Bestimmung von in Wasser gelöstem Sauerstoff wird angegeben. Sie beruht auf der Reaktion einer entfärbten Lösung von Mangan(I)-Formaldoxim mit Sauerstoff. Die Reduktion einer Mangan(II)-Formaldoxim-Lösung läßt sich mit Hilfe von Zinkpulver gut durchführen. Der dazu nötige Apparat ist leicht herstellbar, die dazu erforderlichen Reagenzien von üblicher Qualität. Die bei der Reaktion entstehende Färbung ist stabil. Nitrat, Nitrit, zweiwertiges Eisen, organische Substanzen usw. stören die Methode nicht.