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).     

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.     

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.     

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 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 study of the formaldehyde-leuco-methylene blue reaction

The sensitivity of the reaction between foimaldchyde and Icuco-mcthyleno blue has been found to be increased in the presence of ethyl alcohol, acetone, dicthyl ketone and methyl ethyl ketone. Acetone has been found to be most effective. Sensitisers increase the absorption maximum and stabilise it, while the rate of development of methylene blue colour is slowed down.Sensitivity also depends upon the content of thiosulphate used to prepare the Icuco-base; a smaller amount of thiosulphate increases greater sensitivity.     

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.     

Spectrophotometric determination of osmium with 1-naphthylamine-4,6,8-trisulfonic acid

This investigation was undertaken to determine if the naphthylamine sulfonic acid-osmate (OsVI) reaction is suitable for a spectrophotometric determination of osmium. The 1-naphthylamine- 4, 6,8-trisulfonic acid osmate complex is water-soluble and forms a stable violet-colored system at PH 1 to 1.5 that is independent of reagent concentration. At 555 mμ the colored complex obeys Beer's law over a concentration range of 0.1 to 6.5 p.p.m. osmium and remains stable with respect to time and temperature. The effects of pH, temperature, reagent concentration, and diverse ions were studied. The nature of the organo-osmate complex in solution was studied by three techniques and the effect of temperature and pH on the rate of complex formation was determined. A procedure for the removal of osmium from all interfering ions was developed based on well known distillation techniques.A convenient, sensitive, reproducible and accurate method for the spectrophotometric determination of osmium has been developed.     

Spectrophotometric and fluorimetric determination of nomifensine maleate

Three methods have been developed for the determination of nomifensine maleate alone and in capsules: a spectrophotometric, an iodine charge-transfer, and a spectrofluorimetric method. All three give linear calibration graphs, over the ranges 20-100, 1-5 and 0.1-0.5 microg/ml, respectively, with coefficients of variation of 0.8, 1.3 and 1.3%, respectively.     

Spectrophotometric study of the reaction of zinc with O-hydroxybenzenediazoaminoazobenzene and its application

A highly sensitive and selective procedure for spectrophotometric determination of zinc has been developed. At pH 10.6, in the presence of emulsifier p-octylpolyethyleneglycol phenylether (OP), zinc forms an orange-red complex with o-hydroxybenzenediazoaminoazobenzene (HDAA) which has an absorption maximum at 525 nm. The molar absorptivity is 1.50 x 10(5) 1.mole(-1).cm(-1). Beer's law is obeyed for zinc in the range 0-13 mug/25 ml. The method has been applied to the spectrophotometric determination of trace amounts of zinc in aluminium alloy and in human hair. The proposed method is simple, rapid and accurate. No heating or separation is required.     

Spectrophotometric determination of osmium with 2R-acid in the presence of other platinum metals

Osmium(VIII) produces two coloured species with lambda(max) 680 nm (green) and 530 nm (red) with excess of 2-amino-8-naphthol-3,6-disulphonic acid in aqueous solution. The green complex is stable between pH 2.5 and 8.0 and the red complex between pH 11.0 and 12.0. The effects of temperature and time, reagent concentration, optimum conditions for the spectrophotometric determination of trace amounts of osmium, and other variables, have been studied at pH 11.5. At this pH, other platinum metals do not interfere. The sensitivity of the colour reaction is 0.2 microg/cm(2) and the system conforms to Beer's law over a concentration range of 1.5-10 microg of osmium.