Kinetic-catalytic determination of osmium by fluorescence quenching with salicylfluorone and hydrogen peroxide

A highly sensitive and selective fluorescence-quenching kinetic method is proposed for the determination of trace osmium(IV), based on the catalytic effect of osmium(IV) on the salicylfluorone (_ex = 510 nm, _em = 535 nm)-H₂O₂ system at pH 9.3–9.6. Using the fixed time method, osmium(IV) in the range 0.008–0.6 ng/ml can be determined. The detection limit is 0.006 ng/ml. Over thirty anions and cations, including other platinum metal ions, do not interfere, even when present in large excess. The method has been applied successfully for the determination of osmium in a series of synthetic mixtures and refined ore with relative standard deviations of 2–6%.     

Kinetic-catalytic determination of vanadium in non-aqueous solvents

Determination of trace vanadium in organic solvents is studied by use of the oxidation of o-dianisdine with t-butyl hydroperoxide. The sensitivity of the catalyzed reaction is optimized by application of a modified simplex method. Under optimum conditions the detection limit is 0.7 ng V ml^?1 in acetonitrile and the relative standard deviation is 0.048. The effect of other metal ions and of co-solvents is discussed. The method is used for trace determinations of vanadium in organic solvents of high purity.     

Spectrophotometric determination of osmium

Summary m-Amino benzoic acid in large excess reacts with tetra-, hexa- and octavalent osmium at theph range 4.5–6 to give a purple complex having absorption maximum at 500 nm. Beer's law is obeyed for 0.5 to 8 ppm of osmium(VI) and osmium(VIII) with optimum concentration range of 2 to 8 ppm of osmium(VI) and 3 to 8 ppm for osmium(VIII). The per cent relative error per 1% absolute photometric error is 2.8 for both osmium(VI) and osmium(VIII). Ions such as Pd²⁺, Rh³⁺, Ir⁴⁺, W⁶⁺, U⁶⁺, Co²⁺, Hg²⁺, Mg²⁺, Ca²⁺, Ba²⁺, Sr²⁺, Th⁴⁺ and Zr⁴⁺ do not interfere in the determination.Molar ratio method indicates that the reagent first reduces osmium (VIII) and osmium(VI) to osmium(IV), which then probably forms a 11 complex with the excess unoxidised reagent.Part III.: Anal. chim. Acta 22, 306 (1960); cf. Z. analyt. Chem. 177, 291 (1960).     

Kinetic-catalytic determination of vanadium(IV) using methyl orange-bromate redox reaction.

Determination of V(IV) based on its catalytic effect on the reaction between Methyl Orange and bromate in thepresence of citric acid was studied. The calibration curve obtained by fixed-time method was linear in the range of 2.5-300 ng ml(-1). By use of slope method, a calibration curve containing two linear portions were obtained. Using fixed-time and slope methods, we obtained detection limits of 0.8 and 1.5 ng ml(-1), respectively. Fe2+, As(III), V(V) and Hg2+ interfered. The method was successful for analysis of water samples.     

Spectrophotometric determination of ruthenium and osmium

The optimum conditions for preparation of stable solutions of ruthenate and osmate, after alkaline fusion of ruthenium(IV) compounds, ruthenium metal and osmium metal in a silver crucible, have been determined. The molar absorptivities of ruthenate and osmate are 1.74 × 10³ 1. mole⁻¹.cm⁻¹ at 465 nm (Ru) and 2.75 × 10³ 1.mole⁻¹.cm⁻¹ at 340 nm (Os) in 2M sodium hydroxide. A differential spectrophotometric method has been developed for determination of ruthenium in ruthenium dioxide, lead ruthenite and bismuth pyroruthenate. Simultaneous spectrophotometric determination is proposed for ruthenium and osmium. The other platinum metals interfere seriously only when present in> 1:1 w/w ratio to Ru.     

Spectrophotometric determination of osmium using o-hydroxythiobenzhydrazide

Summary Osmium(VI) forms a violet complex witho-hydroxythiobenzhydrazide in the pH range 5.4–6.4. The complex is readily extractable in chloroform to give a violet solution which can be employed for the photometry of osmium. The extract shows maximal absorption at 540–550 nm and obeys Beer's law over the concentration range 1.44–14.40g Os ml^–1.g amounts of osmium can be determined witho-hydroxythiobenzhydrazide in the presence of considerable amounts of diverse ions commonly associated with the metal using EDTA as the masking agent. However, gold should be removed prior to the determination of osmium with the reagent. The molar extinction coefficient of the complex and the Sandell sensitivity are 1.18×10⁴ l mole^–1 cm^–1 and 0.016g cm^–2 respectively.

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Zusammenfassung Osmium(VI) bildet mit o-Hydroxythiobenzhydrazid zwischen pH 5,4 und 6,4 eine violette Komplexverbindung. Diese läßt sich mit Chloroform gut extrahieren. Die violette Lösung eignet sich für die photometrische Bestimmung des Osmiums, zeigt maximale Absorption bei 540–550 nm und entspricht zwischen 1,44 und 14,40g Os/ml dem Beerschen Gesetz. Mikrogrammengen Osmium können so neben erheblichen Mengen verschiedener anderer Begleitionen nach deren Maskierung mit ÄDTA bestimmt werden. Gold jedoch muß vorher entfernt werden. Der molare Extinktionskoeffizient beträgt 1,18×10⁴ l · Mol^–1 · cm^–1, die Empfindlichkeit nach Sandell 0,016g · cm^–2.

     

Spectrophotometric determination of osmium with quinisatin oxime

A spectrophotometric determination of osmium has been developed, based on the purple color (absorption maximum at 515 mμ) formed by reaction of osmium with quinisatin oxime in buffered solution of dimethyl formamide and methanol. The absorbances are reproducible, and the system conforms to Beer's law. The method compares favorably in sensitivity with existing methods for osmium. The optimum concentration range (for 1 cm optical path) is about 2 to 10 p.p.m. of osmium. Although the maximum color develops slowly, it is stable for 7 days or longer. Several elements, notably iron, cobalt, and ruthenium, interfere, so that separation, is necessary. A reaction ratio of 1:2 for osmium and quinisatin oxime was clearly indicated; some evidence was also obtained for the presence of higher complexes.     

Spectrophotometric determination of osmium with 1,5-diphenylcarbazide

The formation of the bluish violet osmium-diphenylcarbazide complex in weakly acidic solution is utilized for the determination of osmium by spectrophotometry. When measurements are made at 560 nm, after extraction of the complex into isobutyl methyl ketone, Beer's law is obeyed up to 150 mug of osmium. Relatively few ions interfere, and these can be masked with EDTA and fluoride.     

Spectrophotometric determination of osmium with ethylisobutrazine hydrochloride

The sheath flow cuvette is used for refractive index determinations of neat solutions within picoliter probe volumes. In this detector, a sample stream is injected as a narrow stream into the center of a flowing sheath stream under laminar flow conditions. The sample stream retains its identity as a thin cylinder through the center of a 250-m square flow chamber. The propagation properties of a focused helium-neon laser are perturbed by interaction with the sample stream. Detection limits of RI=3×10^–6 were obtained within a 20 micrometer radius sample stream, corresponding to about a 400 picoliter probe volume. For analyte with refractive index significantly different than the solvent, detection limits are possible which correspond to a few picograms of analyte within the probe volume.     

Spectrophotometric determination of osmium with ammonium thiocyanate

Summary A spectrophotometric method for the determination of osmium using ammonium thiocyanate is described. A stable reddish brown colour with an absorption maximum at 440 nm is produced when osmium tetroxide is heated for 30 min at a p_H between 1 to 4 over a boiling water bath with excess reagent. The recommended concentration range is from 3 to 15 ppm of osmium in aqueous medium and from 0.6 to 1.5 ppm when the brown colour (which turns blue) is extracted into isoamyl alcohol. Errors are about ± 1.5%.

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Zusammenfassung Zur spektrophotometrischen Bestimmung von Osmium wird als Reagens Ammoniumthiocyanat empfohlen. Bei Erwärmung von Osmiumtetroxid bei p_H 1–4 mit überschüssigem Reagens (30 min) wird eine beständige rötlich-braune Färbung mit einem Absorptionsmaximum bei 440 nm gebildet. Der günstigste Konzentrationsbereich ist 3–15 ppm in wä\rigem Medium bzw. 0,6–1,5 ppm, wenn mit Isoamylalkohol extrahiert wird (wobei die Farbe nach Blau umschlägt). Die Fehler betragen etwa ± 1,5%.

     

Spectrophotometric determination of osmium using acenaphthenequinonemonoxime (AQM)

A water-soluble dark-brown complex formed by osmium with acenaphthenequinonemonoxime exhibits an absorption maximum at 430 nm. The composition of the complex comes out to 1:2 (metal:ligand) as revealed by Job's method of continuous variations, logarithmic method, and Gerade method of Asmus. The pH range for complete formation of the complex is 6.5–8.5. Its sensitvitiy has been found to be 0.0323 μg/cm². The effect of diverse ions has also been investigated.     

Flow injection kinetic spectrofluorimetric determination of trace amounts of osmium

A flow injection (FI) kinetic spectrofluorimetric method is described for the determination of osmium(IV) and the possible mechanism of catalytic reaction is discussed. The method is based on the fluorescence enhancing reaction of o-vanillin furfuralhydrazone (OVFH) with potassium bromate, which is catalyzed by Os(IV) in water medium at pH 6.10 and 45 degrees C. OVFH is newly synthesized and its ionization, IR and elemental analysis are established. Under these experimental conditions, the oxidized product of OVFH has excitation and emission maxima at 337 and 490 nm, respectively. The linear range of this method is 0-600 ng ml(-1) with the R.S.D. of 1.2%. The detection limit is 1.0 ng ml(-1) of Os(IV). A high analysis rate of 24 samples h(-1) is obtained by the FI method. The proposed method is applied successfully to determine Os(IV) in synthetic mixture and mineral samples, and the results are well consistent with the standard values.     

Spectrophotometric determination of osmium: Sulphanilic acid as a reagent

Sulphanilic acid has been found to be a very effective reagent for the spectrophotometric determination (if hexavalent and octavalent osmium in the pH range between 1.8 – 3.5. In these two valence states, the element forms a dark-violet complex with the reagent, the absorption maximum of the complex being at 490 mμ. As most of the other ions interfere in the determination, the element must be separated as osmic acid by nitric acid distillation. Beer's law is obeyed in the case of 0.5 to 9 p.p.m. of osmium (VIII) and l to 18 p.p.m. of osmium (VI); tin-optimum concentration ranges are from 2 to 8 p.p.m. for osmium(VIII) and from 4 to 16 p.p.m. for osmium(Vl). In these ranges, the % relative errors per 1% absolute photometric error are 3.02 for osmium (VIII) and 3.1 for osmium(VI). Application of the method of continuous variations and the molar ratio method indicates that in solution hexavalent osmium and the reagent form a 1:2. complex, with an average dissociation constant of 1.2 ? 10^-7.     

Spectrophotometric determination of osmium (VIII) with promazine hydrochloride

Promazine hydrochloride is proposed as a new reagent for the spectrophotometric determination of osmium (VIII). The reagent forms orange oxidation product with osmium tetroxide at room temperature in acidic media. The effects of acid concentration, time, temperature, and foreign ions are reported. Beer's law is obeyed in the osmium concentration range 1–10 μg/ml.