Spectrophotometric determination of dissolved oxygen with tris(4,7-dihydroxy-1,10-phenanthroline)iron(II)

Tris(4,7-dihydroxy-1,10-phenanthroline)iron(II) reacts rapidly and quantitatively with dissolved oxygen in alkaline aqueous solution. In ammoniacal solution, the reaction is accompanied by the disappearance of the intense red colour of the iron(II) compound, which gives way to the pale gray, slightly-dissociated ion tris(4,7-dihydroxy-1,10-phenanthrolinefiron)(III). By measurement of the absorbance of a solution containing the ferrous compound before and after the injection of an oxygen-containing solution, the concentration of dissolved oxygen in the sample can be accurately determined in the range 1-20 ppm.     

Photometric determination of iron (III)

A sensitive colored reaction of tiron with iron (III) is described. It is based on a complex formation between tiron and iron (III) in basic medium. The method is suitable to determine 0.4–10 ppm of iron (III) with a relative standard deviation of 0.45–1.4% depending on the concentration level, molar absorptivity of 5.7 × 10³ liter mol⁻¹ cm⁻¹, and Sandell sensitivity index of 0.0098 μg/cm².Because of being simple and rapid, this method can certainly be used in routine analysis.     

Detection of manganese(II) with cacotheline

Analytical and Bioanalytical Chemistry -     

Thermal decomposition of hydrated iron(II) oxalate and manganese(II) oxalate in vacuum

The thermal decomposition of hydrated iron(II) oxalate and manganese(II) oxalate under high vacuum conditions (10^–5 mm Hg) has been studied by differential thermal analysis. The decomposition in vacuum of iron(II) oxalate is exothermic, while that of manganese(II) oxalate is endothermic. An explanation is offered for this behaviour.The financial support by National Bureau of Standards, U.S.A., through a PL-480 scheme is gratefully acknowledged.     

Photometric determination of aluminium with alizarin fluorine blue

In order to decide whether Alizarin Fluorine Blue (alizarin complexan, 3-amino-methylalizarin-N,N-diacetic acid) is a suitable reagent for the spectrophotometric determination of aluminium, values of the stability constants for some reactions of this reagent with aluminium(III) and iron(III) have been determined spectrophotometrically in a medium containing 20 % dioxan and 80 % water at ionic strength 0.1. The values of the constants that were determined are log K(Al)(AlHL) = 14.3, log K(2Al)(Al2L) = 25.3 and log K(Fe)(FeHL) = 19.6. These results were employed in the design of a method for the spectrophotometric determination of aluminium in the presence of iron and titanium. The Sandell sensitivity is 0.01 mug/cm(2) and the coefficient of variation for 34 determinations was 0.9 %.     

Use of a ruthenium(III), iron(II), and nickel(II) hexacyanometallate-modified graphite electrode with immobilized oxalate oxidase for the determination of urinary oxalate.

This paper describes the performance of a biosensor with an Ru(III), Ni(II), and Fe(II) hexacyanometallate-modified graphite electrode and immobilized oxalate oxidase for the determination of urinary oxalate. The addition of ruthenium enhances the electrochemical reversibility and chemical stability of the electrocrystallized layer and improves the sensitivity of the biosensor. Hydrogen peroxide, produced by the enzyme-catalyzed oxidation of oxalate, was measured at -50 mV vs an Hg Hg2CI2 3M KCl electrode in a solution of pH 3.6 succinic buffer, 0.1 M KCl, and 5.4mM ethylenediaminetetraacetic acid. The linear concentration range for the determination of oxalate was 0.18-280 microM. The recoveries of added oxalate (10-35 microM) from aqueous solution ranged from 99.5 to 101.7%, whereas from urine samples without oxalate (or with a concentration of oxalate below the detection limit) the recoveries of added oxalate ranged from 91.4 to 106.6%. The oxalate in 24 h urine samples, taken during their daily routine from 35 infants and children, was measured and found to range from 0.6 to 121.7 mg/L. There were no interferences from uric acid, acetylsalicylic acid, and urea in the concentration range investigated, but paracetamol and ascorbic acid did interfere. A good correlation (R2 = 0.9242) was found between values obtained for oxalate in real urine samples by 2 laboratories, with the proposed biosensor and ion chromatography, respectively.     

Photometric determination of molybdenum in iron and steels using tin(II) chloride in nonaqueous solvent

Summary A new procedure is proposed for the photometric determination of molybdenum in iron and steels using thiocyanate and tin(II) chloride solution [in glycerol-ethannol (31) or in diethylenglycol] as a reducer and extraction with n-butyl acetate. Beer's law is obeyed between 0.2 and 80 g Mo/ml. The minimum photometric error is 3.2%, the molar absorptivity is 15640 at 470 nm and the best concentration range for determination is between 0.6 and 6 g Mo/ml.

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Photometrische Bestimmung von Molybdän in Eisen und Stahl mit Hilfe von Zinn(II)-chlorid in nichtwärigem Medium

Zusammenfassung Das vorgeschlagene Verfahren beruht auf Bildung des Thiocyanatkomplexes unter Verwendung von Zinn(II)-chlorid als Reduktionsmittel [in Glycerin/Äthanol (31) oder Diäthylenglykol]. Als Extraktionsmittel dient n-Butylacetat. Das Beersche Gesetz wird im Bereich 0,2–80 g Mo/l befolgt. Der kleinste photometrische Fehler beträgt 3,2%, die molare Extinktion 15640 bei 470 nm und der optimale Konzentrationsbereich 0,6–6 gMo/l.

Lecture presented at Euroanalysis I Conference, 28. 8. –1. 9. 1972 in Heidelberg, Germany.     

Polarographic determination of iron(II) and iron(III) complexes with edta

The iron(II) and iron(III) complexes with EDTA can be determined separately and in mixtures in acetate-buffered medium at pH 4.0. The E_{$\text{1}\text{2}$}values are in the range ?0.105 to ?0.112 V vs. SCE. Linear calibration plots are obtained over the range 0–1.0 mM for each oxidation state. A sample-handling procedure for avoiding oxidation of iron(II) species is described. It is shown that the acetate buffer system does not affect the stability of the iron-EDTA complexes.     

Photometric determination of tellurium with bismuthiol II

A method for the photometric determination of tellurium based on the extraction of the yellow-coloured complex of tellurium with bismuthiol II is presented. The described method permits the determination of as little as 0.01 % of tellurium in ores directly without preliminary separation. After the isolation of the element by reduction with tin^II chloride even smaller amounts can be determined.     

Spectrophotometric determination of iron (II) with quinisatin oxime

A sensitive spectrophotometric determination of iron is based on the blue color (absorption maximum at 660 mμ) formed by reaction of iron (II) with quinisatin oxime in buffered solution containing ethyl alcohol and a small amount of dimethylformamide. The color develops rapidly and is stable for a few h. The absorbance is well reproducible, and conforms to Beer's law. The optimum concentration range at 1 cm optical path is about 0.5 to 2.5 p.p.m. of iron. Small amounts of iron(III) are reduced by the reagent and cause no difficulty. Cobalt and nickel interfere. Iron(II) and quinisatin oxime react in a 1:3 mole ratio; some possible modes of complex formation are suggested.     

Photometric titration of titanium(III) with iron(III)

An oxidimetric titration of titanium(III) with iron(III) with a photometric end-point is proposed. Acetylacetone was used to obtain an intensely coloured titanium(III) complex; titanium(III) was formed by prereduction with chromium(II) or vanadium(II). Amounts of titanium down to 35 μg were determined with fairly good accuracy and precision. Few common elements interfere.     

Flow-injection determination of iron(II), iron(III) and total iron with chemiluminescence detection

Iron(II) (1.0 × 10^?9–1.0 × 10^?6 M) is determined by the production of chemiluminescence in a luminol system in the absence of added oxidant. Iron(III) (2.0 × 10.8^?8–2.0 × 10^?6 M) is determined after reduction to iron(II) in a silver reductor mini-column in the flow system. Cobalt, chromium, copper and manganese interfere.     

Photometric titration of iron with ethylenediaminedi(o-hydroxyphenylacetic acid)

Fractional mg quantities of ferric iron in 100 ml of solution can be titrated at PH 3.5 with a solution of ethylenediaminedi(o-hydroxyphenylacetic acid). The end-point is found photo- metrically. Errors are generally under 1%, and a number of metals do not interfere. By scaling down the volume of the solution and the titrant concentration, the titration can be extended to μg quantities of iron, and mg quantities are also accessible by changing to a wave length where the sensitivity is not so great. The titration may be useful in certain applications.     

Sequential flow-injection spectrophotometric determination of iron(II) and iron(III) by copper(II)-catalyzed reaction with Tiron

A flow injection method for the sequential determination of iron(II) and iron(III) was developed. It is based on the differential reaction kinetics of iron(II) and iron(III) with Tiron in a double-injection FI system. The proposed method employs the accelerating action of copper(II) for the oxidation of iron(II) in the presence of Tiron. A linear calibration graph is obtained for iron (II) and iron(III) in the concentration range 1.8 × 10^–5– 1.8 × 10^–4 mol/L; the throughput of samples is 30 injections/h. Received: 22 October 1996 / Revised: 4 December 1996 / Accepted: 10 December 1996     

Sequential flow-injection spectrophotometric determination of iron(II) and iron(III) by copper(II)-catalyzed reaction with Tiron

A flow injection method for the sequential determination of iron(II) and iron(III) was developed. It is based on the differential reaction kinetics of iron(II) and iron(III) with Tiron in a double-injection FI system. The proposed method employs the accelerating action of copper(II) for the oxidation of iron(II) in the presence of Tiron. A linear calibration graph is obtained for iron (II) and iron(III) in the concentration range 1.8 × 10^–5– 1.8 × 10^–4 mol/L; the throughput of samples is 30 injections/h.     

Photometric determination of aqueous cobalt (II), nickel (II), copper (II) and iron (III) with 1-nitroso-2-naphthol-3,6-disulfonic acid disodium salt in gelatin films

Photometric determination of aqueous Co(II), Cu(II), Ni(II) and Fe(III) was performed using indicator films prepared by immobilization of 1-nitroso-2-naphthol-3,6-disulfonic acid disodium salt (NRS) into hardened photographic film. Immobilization was based on electrostatic interaction of reagent and metal complexes with the gelatin. The isoelectric point pH of hardened gelatin (4.46±0.04) was evaluated by viscometry. Co(II), Fe(III), Ni(II) form 1:3 complexes with NRS in gelatin at pH 2 and Cu(II) forms 1:2 complexes. Their log β′ values were: Co-6.7, Fe-8.6, Cu-8.0, and Ni-6.4. The absorption maxima were: 370nm for NRS, and 430nm, 470nm, 495nm and 720nm for complexes of Co(II), Ni(II), Cu(II) and Fe(III). An algorithm for their simultaneous determination using the indicator films was developed. The detection limits were: c_lim(Co²⁺) = 0.45×10⁻⁵ M, c_lim(Fe³⁺) = 0.50×10⁻⁵ M, c_lim(Cu²⁺) = 0.67×10⁻⁵ M, c_lim(Ni²⁺) = 0.75×10⁻⁵ M,; and their sum c_lim(ΣMn⁺) = 0.82×10⁻⁵ M.