Indirect atomic-absorption determination of boron by solvent extraction as tris(1,10-phenanthroline)cadmium tetrafluoroborate

An indirect atomic-absorption method for boron has been developed. Boric acid is converted into tetrafluoroborate and extracted into nitrobenzene with Tris(1,10-phenanthroline)cadmium(II). The cadmium in the extract is determined by its atomic-absorption at 228s>d8 nm. A fivefold molar excess of the cadmium chelate is necessary for the extraction from pH 4>d3-6>d0 medium. The sensitivity for boron is thus made about the same as that of cadmium, 0>d005 ppm. Metal ions that react with fluoride or phenanthroline interfere. A procedure is described for determination of boron in steel.     

A new method for the spectrophotometric determination of pertechnetate with tris(1,10-phenanthroline)iron(II) ion

A new spectrophotometric determination of technetium has been developed by means of the solvent extraction of tris(1,10-phenanthroline)iron(II) ([Fe(phen)₃ ²⁺]) with pertechnetate into nitrobenzene. The concentration of technetium can be determined by measuring the characteristic absorbance at 516 nm (=11,700M^–1·cm^–1) in the organic phase. An important feature of the proposed method is that the concentration of pertechnetate can be determined without complicated processes such as the reduction of pertechnetate and the subsequent formation of a colored chelate.     

Indirect spectrophotometric determination of palladium using 1,10-phenanthroline as reagent

Summary The spectrophotometric method for the determination of palladium is based upon the addition of a standard 1,10-phenanthroline solution to precipitate Pd(phen)Cl₂ and the determination of 1,10-phenanthroline concentration of the supernatant solution. The absorbancy readings were made in the absorption maximum at about 271 nm, in the concentration range of 10^–6 to 10^–5M 1,10-phenanthroline in 0.1 M hydrochloric acid and 0.1% hydroxylamine hydrochloride. For the phenanthroline system Beer's law is valid. Ions which either form with phenanthroline very strong complexes or interfere with the spectrophotometric determination of 1,10-phenanthroline must be absent. The method is simple, rapid, accurate and applicable to the macro and micro-determination of palladium in different systems. Standard deviation was found to be 0.085 ppm (in pure Pd solutions).

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Indirekte spektrophotometrische Bestimmung von Palladium mit 1,10-Phenanthrolin

Zusammenfassung Das Verfahren beruht auf der Fällung von Pd(phen)Cl₂ durch Zusatz einer bestimmten Menge Standard-1,10-Phenanthrolinlösung und spektrophotometrischer Bestimmung des Überschusses.Die Messungen werden bei dem Absorptionsmaximum bei etwa 271 nm und einer Konzentration von 10^–6M bis 10^–5M 1,10-Phenanthrolin in 0,1 M HCl und 0,1% Hydroxylaminhydrochlorid enthaltender Lösung durchgeführt. Das 1,10-Phenanthrolinsystem folgt dem Beerschen Gesetz. Ionen, die entweder mit 1,10-Phenanthrolin starke Komplexe bilden oder die spektrophotometrische Bestimmung von 1,10-Phenanthrolin beeinflussen, müssen abwesend sein. Die Methode ist einfach, rasch und genau und kann für Mikro- und Makrobestimmungen in verschiedenen Systemen angewendet werden. Die Standardabweichung beträgt 0,085 ppm (in reinen Pd-Lösungen).

     

Transient bleaching of tris(1,10-phenanthroline) iron(II)

Absorption at the excitation wavelength recovers in a sub-nanosecond, two stage process following bleaching of tris(1,10-phenanthroline) iron(II) by a single picosecond pulse at 530 nm. Absorption coefficients and decay times suggest that a CT and a dd excited state are consecutively occupied before ground state repopulation.     

The spectrophotometric determination of anions by solvent extraction with metal chelate cations. part XX : Trichloroacetic acid with tris(1,10-phenanthroline)iron(ii) chelate

Trichloroacetic acid can be extracted from an aqueous solution by nitrobenzene with tris(1,10-phenanthroline)iron(II) chelate, and can be determined spectrophotometrically by measuring the extract at 516 nm. The extracted species is probably [Fe(phen)₃].(CCl₃COO)₂. Beer's law is obeyed over the concentration range 1.0·10^-5–1.0·10^-4M trichloroacetic acid in aqueous solution. Large amounts of phosphate and sulfate and moderate amounts of chloride, acetic acid, and monochloroacetic acid do not interfere, equal amounts of dichloroacetic acid give a slight positive error     

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.     

Indirect extraction—spectrophotometric method for the determination of traces of tin(II) by means of 4,7-diphenyl-1,10-phenanthroline

An indirect extraction-spectrophotometric determination of tin(II) is based on reduction of iron(III) and determination of the iron(II) formed with bathophenanthroline. Analysis is possible in strongly acidic samples even with large excesses of iron(III). The apparent molar absorptivity is 39,080 dm³ mol^-1 cm^-1 ; the limit of determination is 32 ng cm^-3 and the sensitivity is 64 ng cm^-3. Interferences are reported. The method is applicable to the determination of tin in samples soluble in non-oxidizing acids, and to the determination of tin in lead.     

Kinetic spectrophotometric determination of antimony(III) based on induced oxidation of tris(1,10-phenanthroline)iron(II) by chromium(VI)

The method involves the measurement of the extent of the induced reaction, which ceases a few seconds after initiation. Antimony(III) can be determined in the range 0.4–10 μg ml^-1. The standard deviation is ±0.25 μg. The method is applied to marine sediments.     

Sequential injection spectrophotometric determination of iron as Fe(II) in multi-vitamin preparations using 1,10-phenanthroline as complexing agent

A sequential injection analysis (SIA) system is proposed for the determination of iron (II). Fe(II) was determined by SIA based on the reaction between 1,10-phenanthroline and iron (II), yielding an orange–red colour complex with absorption maximum at 512 nm. The method involved aspiration of 187 μl sample/standard zone followed by a zone of a reagent solution containing 140 μl of 7.8 × 10⁻⁴ mol l⁻¹ 1,10-phenanthroline into a carrier stream to be stacked inside a holding coil and flow reversed through a reaction coil to a detector. The optimum condition was evaluated and the calibration curve is linear over a range of 0.25 to 5.0 mg l⁻¹ of Fe(II) with detection limit of 18 μg l⁻¹. A sample throughput of 40 h⁻¹ was established. This technique is found to be simple, accurate, reproducible and sensitive. The proposed method was successfully applied for the determination of total iron as Fe(II) in pharmaceutical products (multi-vitamin tablets) and is especially useful for the determination of iron (II) in tablets with lower iron (II) contents. The results were found to be in good agreement with the results obtained by manual UV/Vis spectrophotometry and flame atomic absorption spectrometry (FAAS) and with claimed values by the manufacturers.     

Indirect spectrophotometric determination of thiocyanate by extraction as bisthiocyanatobisquinolinemercury(II) complex and its ligand substitution reaction with dithizone

Thiocyanate forms with mercury(II) in the presence of quinoline a mixed-ligand mercury(II) complex, bisthiocyanatobisquinolinemercury(II), and is extracted into chloroform. This mixed-ligand complex is treated with dithizone and forms the bisdithizonatomercury(II) complex. Maximum and constant absorbance of the dithizone complex is obtained when thiocyanate is extracted at pH 5.1-6.5, and Beer's law is obeyed at 498 nm, where the difference in absorbance between the dithizone complex and dithizone is largest. Chloride, bromide, iodide, cyanide and large amounts of ammonium and copper(II) ions interfere.     

Indirect complexometric determination of cadmium(II) using 1,10-phenanthroline as selective masking agent

An indirect complexometric method is described for the determination of cadmium(II), 1,10-phenanthroline being used as masking agent. Cadmium(II) in a given sample solution is initially complexed with an excess of EDTA and the surplus EDTA is titrated with lead nitrate solution at pH 5.0–6.0 (hexamine), using xylenol orange as indicator. An excess of 1,10-phenanthroline is then added and the EDTA released from the Cd-EDTA complex is titrated with standard lead nitrate solution. Results are obtained for 1.5–57 mg of Cd with relative errors 0.90% and standard deviations 0.06 mg. Cu(II), Co(II), Hg(II), Ni(II), Zn(II), Pd(II), Tl(III), Au(III) and Sn(IV) interfere, but can be easily masked. The method is applied for the determination of cadmium in synthetic alloy solutions.     

Thin-layer chromatography of tris(1,10-phenanthroline)iron(II) and tris(2,2′-bipyridine)iron(II) on Sephadex G gels

Summary Gel chromatographic behaviour of tris(1, 10-phenanthroline)iron(II), tris(2,2′-bipyridine)iron(II) and tris(glycinato)cobalt(III) on Sephadex G-10 or G-25 was investigated by TLC with 0.001–1.0M NaCl as the eluent. The zone shapes and R_M values of tris(1,10-phenanthroline)iron(II) and tris(2,2′-bipyridine)iron(II) were appreciably dependent on the sample and eluent concentration, while the neutral complex, tris(glycinato) cobalt(III), exhibited the round zones with constant R_M values. The order of R_M values was found to be tris(glycinato)cobalt(III<tris(2,2∔pyridine)iron(II)<tris-(1,10-phenanthroline)iron(II) in all systems studied, although the reverse trend was expected when assuming the chromatographic behaviour of solute compounds to be controlled by the “sieving effect”. The comparison of the behaviour on Sephadex G gels with that on CM-cellulose revealed that the predominant mechanism involved is not the sieving effect, but ion-exchange and/or hydrophobic interaction.     

Conductance of tris(1,10-phenanthroline)iron(II) and tris(2,2'-bipyridine)iron(II) halides and perchlorates in water and nitrobenzene in relation to solvent extraction of the ion pairs

Conductances of tris(l,10-phenanthroline)iron(II) and tris(2,2'-bipyridine)-iron(II) chlorides, bromides, iodides, and perchlorates were measured in water and nitrobenzene at 25°. Experimental data were analyzed by the Fuoss-Edelson and Jenkins-Monk methods for 2:1 electrolytes. The derived parameters indicated that all the salts studied are almost completely dissociated in water, whereas in nitrobenzene, the association constants were of the order expected from electrostatic theory, which was in turn the order of distribution ratios of the ion pairs between water-and nitrobenzene. An approximately linear relationship was obtained between log k_a1(0) and log D. It is suggested that for the analysis of the mechanism of the extraction of these ion pairs into nitrobenzene, ionic association in the nitrobenzene phase must be considered an important factor.     

Electrochemical behavior of 5-amino-1,10-phenanthroline and oxidative electropolymerization of tris[5-amino-1,10-phenanthroline]iron(II)

The electrochemical behavior of 5-amino-1,10-phenanthroline and tris[5-amino-1,10-phenanthroline]-iron(II) at carbon paste, glassy carbon, and platinum electrodes is reported. The iron complex undergoes electrochemically induced oxidative polymerization from acetonitrile solutions and the resulting polymers are very stable. Charge transport through the polymer films occurs with a charge transfer diffusion coefficient, D_ct, equal to 3.1 × 10⁻⁸ cm² s⁻¹ corresponding to an electron self-exchange rate of 5.2×10⁷M⁻¹ s⁻¹. The activation energy and the entropy change for the charge transfer diffusion process are (approximate values) 32.0 ± 0.12 kJ mol⁻¹ and −24.7 ± 0.4 J K⁻¹ mol⁻¹, respectively.     

Solvent extraction of anions with metal chelate cations-XVIII Spectrophotometric determination of maleic acid in the presence of fumaric acid by solvent extraction with tris(1,10-phenanthroline)iron(ii) chelate cations

A new colorimetric method is proposed for the determination of maleic acid. Among aliphatic dicarboxylic acids tested, maleic acid was found to be selectively extracted into nitrobenzene as the red ion-association complex (lambda(max) 516 nm) formed between the hydrogen maleate anion and the tris(1,10-phenanthroline)iron(II) cation. At least a 32-fold molar excess of tris(1,10-phenanthroline)iron(II) relative to maleic acid is needed and the optimal pH range is 3-5. A linear relationship is obtained over the concentration range 10(-5)-10(-4)M maleic acid. The relative standard deviation was 1.0 %. The colour intensity of the extract remains constant at room temperature for at least 24 hr. A large amount of fumaric acid, the trans-isomer of maleic add, is not extracted under the same conditions. This makes it possible to determine maleic acid in the presence of fumaric acid.     

A simple method for the spectrophotometric determination of chloride by solvent extraction as chromyl chloride

Summary A simple and direct method for the spectrophotometric determination of chloride, based on the formation of chromyl chloride and its extraction into carbon tetrachloride has been developed. The absorption spectrum of the organic extract shows two bands at 300 and 415 nm; Beer's law is obeyed at both wavelengths over the range 20–320g of chloride. The best conditions for the spectrophotometric determination of chloride are determined and a procedure is recommended. Interferences from some of the most common anions are studied.

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Zusammenfassung Eine neue Methode für die Bestimmung von Chloridionen wurde angegeben. Sie beruht auf der Bildung von Chromylchlorid und dessen Extraktion mit Tetrachlorkohlenstoff. Der Extrakt hat spektrale Maxima bei 300 und 415 nm. Das Beersche Gesetz ist zwischen 20 und 320g Chlorid erfüllt. Die besten Bedingungen für die spektrophotometrische Bestimmung wurden ermittelt und ein Verfahren empfohlen. Störungsmöglichkeiten einiger üblicher Anionen wurden untersucht.

     

Colorimetric determination of iron (III) with 1,10-phenanthroline

Summary A new procedure has been developed for the colorimetric determination of iron(III). It consists in the reduction of iron (III) in dilute sulphuric acid medium (0.1 to 1.0 N) with an excess of hypophosphite (1100) at room temperature using one or two drops of 0.1% PdCl₂ solution as catalyst, and then complexing the reduced iron with 1.10-phenanthroline.Iron (III) can also be reduced with phosphite using the PdCl₂ catalyst and boiling for 5 to 10 min on a hot plate. The molar concentration of phosphite is preferably kept 500 times that of ferric ion.

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Zusammenfassung Es wurde ein neues Verfahren zur colorimetrischen Bestimmung von Eisen(III) ausgearbeitet. Dabei wird das Eisen in verd. Schwefelsäure (0,1–1,0 n) mit einem Überschuß von Hypophosphit (1100) bei Zimmertemperatur unter Verwendung von ein oder zwei Tropfen 0,1%iger PdCl₂-Lösung als Katalysator reduziert und anschließend das zweiwertige Eisen mit 1,10-Phenanthrolin umgesetzt.Eisen(III) kann auch mit Phosphit reduziert werden, wenn man ebenfalls PdCl₂ als Katalysator verwendet und 5–10 min erhitzt. Die molare Konzentration des Phosphits soll dabei das 500fache von der des Eisens betragen.