2-Mercaptobenzimidazole (2-benzimidazolethiol) as a colorimetric reagent for palladium

Summary A spectrophotometric method for the determination of palladium using 2-mercaptobenzimidazole is described. The orange-yellow colour developed in aqueous medium atph 1.0–2.6 by the addition of an alcoholic solution of the reagent, is measured at 380 m. The system is found to obey Beer's law. The interference limits of diverse ions are also given.     

Nitroso-R-salt as a reagent for the determination of palladium (II)

Summary A procedure for the determination of palladium with nitroso-R-salt is presented. The sensitivity is 0.068 g/cm².

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Zusammenfassung Es wird ein Verfahren von zur Bestimmung Palladium mit Nitroso-R-Salz beschrieben, dessen Empfindlichkeit 0,068 g/cm² beträgt.

     

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.     

p-Aminoacetophenone as a reagent for the colorimetric determination of cerium(IV)

With a solution ofp-aminoacetophenone, cerium(IV) gives a purple colour which can be used for its detection and determination. The limits of identification and dilution are 1.0 mug and 1 in 50000 respectively. Beer's law is obeyed in the range 14-350 mug. The colour is stable for only 5 min and measurements of absorbance must be made quickly. The interferences are fewer than with existing methods.     

Prochlorperazine bismethanesulfonate as a new reagent for the spectrophotometric determination of palladium

A simple, rapid, and selective method for the determination of palladium is described. The orange-red palladium(II)-prochlorperazine bismethanesulfonate complex in the presence of hydrochloric acid-sodium acetate buffer exhibits maximum absorbance at 480 nm with a molar absorptivity of 4.32 × 10³ liters mol^?1 cm^?1. The sensitivity of the reaction is 24.62 ng cm^?2. The system obeys Beer's law over the concentration range 0.4–20 ppm of palladium with an optimum concentration range of 1–19 ppm. The apparent stability constant of the complex is found to be log K = 5.3 ± 0.1 at 27 °C. The effects of pH, time, temperature, order of addition of reactants, reagent concentration, and interferences from various ions are reported. The proposed method offers the opportunity to carry out the determination at room temperature without the need for an extraction step. The method is also found to be suitable for the determination of palladium in jewelry alloy.     

4(5)-D-Arabinotetrahydroxybutylimidazoline-2-thione (THBIT), a new reagent for the spectrophotometric determination of palladium

Summary 4(5)-D-Arabinotetrahydroxybutylimidazoline-2-thione, THBIT, is proposed as a new reagent for the spectrophotometric determination of Pd(II). Pd(II) forms 11, 12 and 14 complexes with THBIT. The system conforms to Beer's law up to 5g/ml palladium concentration in aqueous medium (molar absorptivity, 1.99×10⁴ l· mole^–1·cm^–1 at 338 nm). The most serious interference is from Hg(II), Os(VIII), Ru(IV), Cr(VI), V(V) and S₂O₃ ^2–. The method has been used successfully for the determination of palladium in catalysts and synthetic samples.     

Metavanadate as a reagent for the colorimetric determination of acids

Acids with pK(a) > 6 can be determined colorimetrically by their reaction with metavanadate, provided they are not coloured and do not give complexation or redox reactions with the polyvanadate.     

Sulfophenylanthranylic acid as a new reagent for palladium

The use of diphenyl reagents bearing electron-withdrawing substituents in catalymetric analysis was studied using sulfophenylanthranilic acid as an example. A selective catalytic effect of palladium(II) on the oxidation of sulfophenylanthranilic acid by cerium(IV) sulfate in a weakly acid solution was found. The reaction rate was studied as a function of component concentrations, solution acidity, and temperature. A procedure for determining palladium(II) was developed and tested using model mixtures and a KP-5 sample of complex composition.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 2, 2005, pp. 144–148. Original Russian Text Copyright © 2005 by Burmistrova, Mushtakova, Nikonorov.     

Colorimetric determination of gold(III) using 3-methyl-4-vanillidine isoxazolone-5

Summary A new color reaction for the determination of gold(III) has been developed. Gold reacts with 3-methyl-4-vanillidine isoxazolone-5 in basic media at 90° to produce a pink color which is specific. Cobalt and nickel do not interfere when present upto 4 folds. Maximum tolerable amounts of other metal ions have also been studied.

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Zusammenfassung Eine neue Farbreaktion zur Goldbestimmung mit 3-Methyl-4-vanillidinisoxazolon-5 in basischem Milieu bei 90° führt zu einer spezifischen Rosafärbung. Kobalt und Nickel stören bis zur vierfachen Menge nicht. Außerdem wurden auch die tolerierbaren Mengen anderer Fremdionen bestimmt.

     

Potassium ferrocyanide as a spectrophotometric reagent for the determination of uranium

Potassium ferrocyanide gives a colour reaction with U(VI), which is suitable for its determination. The complex absorbs in the wavelength range of 390–397 nm. The optimum pH range for colour development was 1.5–3.5. The molar absorptivity was found to be 4.65·10³ 1·mol^–1·cm^–1. Most of the anions up to 1000 g did not interfere. The method was made selective by extracting U(VI) first with DOSO from the mixture of interfering cations from 1–2M HNO₃ medium and then determining uranium in the back-extracted solution by developing the colour with ferrocyanide. 20 g/10 ml of U(VI) in the final solution could be satisfactorily determined within an RSD of ±2%.     

Tris(o-hydroxyphenyl)phosphine oxide as a colorimetric reagent for the determination of ferric iron

Tris(o-hydroxyphenyl)phosphine oxide is introduced as a new colorimetric reagent for the determination of ferric iron in solutions 0.3–2.5M nitric acid. The only other cation known to interfere in the determination is the ceric ion (Ce⁺⁴). The colour of the complex is stable and is found to obey Beer's law over a wide concentration range.     

Gravimetric determination of palladium with quinolinimide as a reagent

Summary Quinolinimide which is found to be a selective reagent for palladium forms a complex of the composition Pd(C₇H₃O₂N₂)₂. The reagent quantitatively precipitates palladium from solutions of p_H 0.5 to 2.5 in presence of common ions as well as platinium metals, except tin which, however, can be kept in solution by complexing with citric acid. The palladium complex being stable up to 307° C can be directly weighed.

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Zusammenfassung Chinolinimid wird als selektives Reagens für Palladium vorgeschlagen. Bei p_H-Werten zwischen 0,5 und 2,5 kann Palladium quantitativ in Form des Komplexes Pd(C₇H₃O₂N₂)₂ gefällt werden, wobei die meisten anderen Ionen, auch die der Platinmetalle, in Lösung bleiben. Zinn stört, kann aber mit Citronensäure maskiert werden. Der Palladiumkomplex ist bis 307° C stabil und kann direkt ausgewogen werden.

     

o-Hydroxyacetophenone thiosemicarbazone as a reagent for the rapid spectrophotometric determination of palladium

o-Hydroxyacetophenone thiosemicarbazone has been synthesized and employed as a new reagent for the spectrophotometric determination of palladium(II), which forms two complex species with it in aqueous dimethylformamide at pH 6.0, these having 1:1 and 1:2 metal-ligand ratios. The Job and molar-ratio plots have an unusual shape that is due to the stepwise conversion of the 1:1 complex into the 1:2 species. The molar absorptivity at 370 nm is 9 x 10(3) l.mole(-1).cm(-1). Beer's law is obeyed over the range 0.42-10.6 mug/ml palladium.