3-Nitroso-4-hydroxy-5,6-benzocoumarin as a selective reagent for the spectrophotometric determination of ruthenium(III)

The pinkish-violet complex developed on interaction of ruthenium(III) with 3-nitroso-4-hydroxy-5,6-benzocoumarin (NHBC) in the pH range 5.5-8.0 can be extracted into n-butanol. The complex has an absorption maximum at 520 nm. Maximum colour development takes place after heating for 20 min on a steam-bath and the extracted complex is stable for at least 92 hr. Beer's law is followed up to 7.4 ppm of ruthenium. The molar absorptivity is 1.04 x 10(4) 1.mole(-1).cm(-1). The composition of the complex is 1 : 2 (ruthenium: NHBC). None of the other platinum metals was found to interfere in the determination of ruthenium, even though present in large excess.     

Arsenazo III as a spectrophotometric reagent for determination of lead

Arsenazo III is proposed as a spectrophotometric reagent for the determination of lead. The complex formation begins at pH > 2 and is greatest at pH 4-6. The molar absorptivity of the complex has a mean value of 2.8 x 10(4) 1.mole(-1).cm(-1) at 600 nm and remains nearly constant in the pH range 4-8. The ionic species taking part in the reaction are studied and the equilibrium constants for the different possible reactions are calculated. According to the values obtained, the reaction of PbOH(+) with H(5)L(3-) is predominant. The reaction studied is applied for the determination of micro amounts of lead in technical aluminium.     

Benzoylacetanilide as a spectrophotometric reagent for iron(III)

Benzoylacetanilide (BAA) forms violet colored complex Fe(BAA)₃ with Fe(III) in 60% alcohol with λmax at 540 nm. The stability constant (log K) and free energy of formation of the complex at 20 °C are log K = 7.8 ± 0.1 and ΔF = −10.53 kcal/mole, respectively. The molar adsorptivity, sensitivity, effect of diverse ions in spectrophotometric determination of iron have also been investigated.     

Propionyl promazine phosphate as a new reagent for the spectrophotometric determination of rhodium(III)

Summary PPP forms an orange-red coloured complex with rhodium(III) at room temperature (27°) in the presence of sodium acetate-hydrochloric acid buffer of pH 1.0–3.0 containing copper(II) and ascorbic acid. The complex exhibits absorption maximum at 470 nm. Beer's law is valid over the rhodium concentration range 0.1–18g/ml. Sandell's sensitivity of the reaction is 1.8·10^–3 g Rh/cm² and the molar extinction coefficient is 5.68×10³ l·mol^–1cm^–1 at 470 nm. The composition of the complex is 11 and the apparent stability constant of the complex at pH 2.5 and 27° has the logK value of 4.0. The proposed method has been used for the determination of rhodium in thermocouple wires and in synthetic mixtures containing palladium, ruthenium, osmium, uranium or iridium.

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Propionylpromazinphosphat (PPP), ein neues Reagens für die spektrophotometrische Bestimmung von Rhodium(III)

Zusammenfassung PPP bildet mit Rh(III) bei Zimmertemperatur (27°) in Gegenwart von Natriumacetat-Salzsäure (pH 1,0–3,0), Cu(II) und Ascorbinsäure eine orange-rote Komplexverbindung mit einem Absorptionsmaximum bei 470 nm. Das Beersche Gesetz gilt für Konzentrationen von 0,1 bis 18g/ml. Die Empfindlichkeit nach Sandell beträgt 1,8×10^–3 g Rh/cm²; der molare Extinktionskoeffizient bei 470 nm ist 5,68×10³ l·mol^–1·cm^–1. Die Zusammensetzung der Komplexverbindung entspricht dem Verhältnis 11, die scheinbare Stabilitätskonstante bei pH 2,5 und 27° entspricht log K=4,0. Das vorgeschlagene Verfahren diente zur Rh-Bestimmung in Thermoelementdraht sowie in synthetischen Gemischen aus Pd, Ru, Os, U und Ir.

     

Diformylhydrazine as analytical reagent for spectrophotometric determination of iron(II) and iron(III)

The bidentate ligand diformylhydrazine (OHC-HN-NH-CHO), DFH, combines with iron(II) and iron(III) in alkaline media in the pH range 7.3-9.3 to form an intensely colored red-purple iron(III) complex with an absorption maximum at 470 nm. Beer's law is obeyed for iron concentrations from 0.25 to 13 microg mL(-1). The molar absorptivity was in the range 0.3258x10(4)-0.3351x10(4) L mol(-1) cm(-1) and Sandell's sensitivity was found to be 0.0168 microg cm(-2). The method has been applied to the determination of iron in industrial waste, ground water, and pharmaceutical samples.     

Rapid spectrophotometric determination of ruthenium(III) with prochlorperazine maleate

A rapid, simple spectrophotometric method for the determination of μg amounts of ruthenium, based on the formation of a pink complex between the metal and prochlorperazine maleate (PCPM) in sulphuric or hydrochloric acid solution, is described. The complex has an absorption maximum at 530 nm and its molar absorptivity is 6.733·10³ l mol^?1 cm^?1. The sensitivity is 0.0151 μg Ru cm^?2 for log I_o/I = 0.001. Beer's law is valid over the range 0.2–10 μg Ru ml^?1 ; the optimal range for spectrophotometric determination is 0.8–8.0 μg Ru ml^?1. Job's method of continuous variation, the mole ratio method and the slope ratio method indicate a 1:1 composition for the complex. The effects of acidity, time, temperature, order of addition of reagents, reagent concentration, and the interferences from various ions are reported.     

Diphenylcarbazone as a sensitive reagent for the spectrophotometric determination of iridium(IV)

Summary The blue iridium(IV)-diphenylcarbazone complex, formed by heating the solutions in boiling water bath for 45 minutes, having an absorption maximum at 550 nm with maximum molar absorptivity of 1.90·10⁴l·cm^–1·mole^–1 (within 1.5 %) is recommended for the spectrophotometric determination of 40–240g iridium(IV) in 25–60 % ethanol medium. The complex formed in solutions at pH 3.5–7.0, after formation, is stable within the pH range 2.5 to 9.2. The effect of foreign ions has been investigated.

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Zusammenfassung Der blaue Iridium(IV)-diphenylcarbazon-Komplex entsteht beim Erwärmen der beiden Lösungen im siedenden Wasserbad für 45 Min. Er hat ein Absorptionsmaximum bei 550 nm und eine molare Extinktion von 1,90 × 10⁴ l·cm^–1·mole^–1. Diese Farbreaktion wird zur spektrophotometrischen Bestimmung von 40–240g Ir(IV) in 25-bis 60%igem Äthanol empfohlen. Der bei pH 3,5–7,0 entstandene Komplex ist zwischen pH 2,5 und 9,2 beständig. Der Einfluß von Fremdionen wurde untersucht.

     

Monothiourea-3-nitrophthalic acid as a new reagent for spectrophotometric analyses : II. Determination of ruthenium(III) ions

The results of the examination of the reaction between a new reagent, MT3NF acid, and palladium(II) ions, as well as the composition of the formed complexes have been discussed. The new extraction-spectrophotometric method for the determination of palladium(II) ions by using MT3NF acid was presented. Beer's law is obeyed over the range 0.1 to 3 μg of Pd/cm³. Molar absorptivity is 2.9 × 10⁴ liter mol⁻¹ cm⁻¹ at the absorption maximum of 306 nm. The influence of different ions has been described.     

Triangular silver nanoplates as a spectrophotometric reagent for the determination of mercury(II)

The applicability of triangular silver nanoplates (TNPs) as a spectrophotometric reagent for the determination of mercury(II) in an aqueous solution was estimated. The method is based on the oxidation of TNPs with a mean edge length of 52 nm and thickness of 4 nm by mercury(II) ions, which is accompanied by a decrease in the surface plasmon resonance of nanoparticles. The effect of reaction time, pH of solution, and TNP concentration on the sensitivity of mercury(II) determination was studied. The limit of mercury(II) detection under the selected conditions was 0.022 μg/mL.     

A new polymeric chromogenic reagent for dual-wavelength spectrophotometric determination of iron(III)

By condensing chitosan with 7-(4-formyl-phenylazo)-8-quinolinol-5-sulfonic acid (FPAQS), a new polymeric chromogenic reagent C-FPAQS has been synthesized and its properties investigated. In acidic media (pH 2.7), C-FPAQS reacts with iron(III) to yield an orange complex with a molar absorptivity of 2.8 × 10⁴ lmol^–1 cm^–1 at 420 nm, and in the meantime a negative peak at 524 nm. The apparent molar absorptivity (420–524 nm) obtained by dual-wavelength measurements is 7.9 × 10⁴lmol^–1cm^–1 which is about two times higher than that by single-wavelength measurements at 420 nm Beer's law is obeyed in the range of 0–0.8 g ml^–1 for iron(III). The developed method has been satisfactorily used to determine iron at the 0.03 to 3% (ww) level in a nylon-6 and in a soil sample. Compared to the corresponding low-molecular weight FPAQS and other chromogenic reagents, C-FPAQS has not only good sensitivity but also largely increased acid solubility and improved selectivity for iron, which may be explained by the incorporation of FPAQS into an acid-soluble polymer.     

p-chloro- and p-bromo-benzoylacetoneoxime as the spectrophotometric reagents for palladium and ruthenium(III)

Summary A procedure is described for the extractive spectrophotometric determination of palladium or ruthenium (III) usingp-chloro orp-bromobenzoylacetoneoxime as the reagent. The yellow palladium complexes which are extracted into chloroform from an aqueous solution of pH 3.5, absorb at 400 nm and conform to Beer's law in the range of 10 to 100g of Pd/10 ml of organic phase. The orange-red ruthenium complexes which are extracted into ethylacetate from an aqueous solution of pH 5.0, absorbs at 475 nm and conforms to Beer's law in the range of 20 to 200g of Ru/10 ml of organic phase. The molar absorptivities, Sandell's sensitivities and instability constants are reported.

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p-Chlor- und p-Brombenzoylacetonoxim als spektrophotometrische Reagenzien für Palladium und Ruthenium(III)

Zusammenfassung Ein Verfahren zur extraktiv-spektrophotometrischen Bestimmung von Palladium und Ruthenium(III) mit p-Chlor- oder p-Brombenzoylacetonoxim wurde beschrieben. Die gelben Palladium-Komplexe werden bei pH 3,5 aus wäßriger Lösung mit Chloroform extrahiert, absorbieren bei 400 nm und entsprechen dem Beerschen Gesetz zwischen 10 und 100g Pd/10 ml organischer Phase. Die orange-roten Ruthenium-Komplexe werden bei pH 5,0 aus wäßriger Lösung mit Äthylacetat extrahiert, absorbieren bei 475 nm und entsprechen zwischen 20 und 200g Ru/10 ml organischer Phase dem Beerschen Gesetz. Über die molare Extinktion, die Empfindlichkeiten nach Sandell und die Instabilitätskonstanten wurde berichtet.

     

Malachite green as a reagent for detection and spectrophotometric determination of chromium(VI)

A sensitive and inexpensive method of spectrophotometric determination of chromium(VI), based on the absorbance of its complex with malachite green and acetic acid at pH 2.5 is reported. The complex shows a molar absorptivity of 8 x 10(4) l.mole(-1) cm(-1) at 560 nm, using malachite green and acetic acid as reference solution. The effect of time, temperature, pH and reagent concentration is studied and optimum operating conditions are established. Beer's law is applicable in the concentration range 2.0-22.8 mug/ml chromium(VI). The resin beads act as a catalyst and as little as 1.6 mug of chromium(VI) is detected in the resin phase as compared to 4.1 mug in the solution phase. The standard deviation in the determinations is +/-0.40 mug/ml for a 10.35 mug/ml solution.     

Reverse flow injection spectrophotometric determination of iron(III) using chlortetracycline reagent

A simple reversed flow injection colourimetric procedure for determining iron(III) was proposed. It is based on the reaction between iron(III) with chlortetracycline, resulting in an intense yellow complex with a suitable absorption at 435 nm. A 200 μl chlortetracycline reagent solution was injected into the phosphate buffer stream (flow rate 2.0 ml min⁻¹) which was then merged with iron(III) standard or sample in dilute nitric acid stream (flow rate 1.5 ml min⁻¹). Optimum conditions for determining iron(III) were investigated by univariate method. Under the optimum conditions, a linear calibration graph was obtained over the range 0.5–20.0 μg ml⁻¹. The detection limit (3σ) and the quantification limit (10σ) were 0.10 and 0.82 μg ml⁻¹, respectively. The relatives standard deviation of the proposed method calculated from 12 replicate injections of 2.0 and 10.0 μg ml⁻¹ iron(III) were 0.43 and 0.59%, respectively. The sample throughput was 60 h⁻¹. The proposed method has been satisfactorily applied to the determination of iron(III) in natural waters.     

Guaiacol as a new reagent for the spectrophotometric determination of uranium

Guiacol, i.e. o-hydroxyanisole, gives a distinct color reaction with U(VI) suitable for spectrophotometric determination of the metal. The complex formed in the reaction has an absorption maximum at 352 nm. Optimum pH for the color development ranges from 6.5 to 8.5. The molar absorptivity and Sandell's sensitivity of the method were found to be 3.75×10³ l·mol^–1·cm^–1 and 0.063 g·cm^–2, respectively. Many anions and cations do not interfere up to 100 ppm. The method has been made very specific by selective extraction of U(VI) with TBP from a mixture of different cations and anions in the presence of 60% NH₄NO₃ as salting out agent followed by developing the color in the non-aqueous phase by adding quaiacol in methanol at pH 6.5 to 8.5 An amount as low as 30 g of uranium (VI) per 10 ml of the solution could be satisfactorily determined with an RSD of ±2.0%. The method was applied to rock samples after U(VI) had been extracted from a sample solution into 25% TBP in hexane. Results obtained by the new method compare very well with those of conventional fluorimetric and radiometric assays. The features of the method include excellent precision, rapidity, good selectivity, and ease of performance.