Spectrophotometric determination of nitroprusside by complex formation with obidoxime

Summary A method for the determination of small amounts of nitroprusside is proposed. Reaction with obidoxime leads to a coloured complex of high molar absorptivity which can be detected spectrophotometrically.

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Spektrophotometrische Bestimmung von Nitroprussid durch Komplexibildung mit Obidoxim (Kurze Mitt.)

Zusammenfassung Eine Methode für die Bestimmung kleiner Mengen Nitroprussid wird vorgeschlagen. Die Methode beruht auf der Reaktion des Nitroprussids mit Obidoxim unter Bildung eines farbigen Komplexes mit hoher Molarabsorption, die man spektrophotometrisch messen kann.

     

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 ketoprofen in pharmaceutical preparations by means of charge transfer complex formation

A spectrophotometric determination of ketoprofen based upon oxime formation followed by charge transfer complexation with o-chloranil has been developed. Different variables affecting the complexation process have been studied. Beer's law is obeyed in the concentration range 10-80 microg/ml. The method has been successfully applied to the determination of ketoprofen in pure form and in pharmaceutical dosage forms in the presence of its impurities.     

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 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 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%.

     

Kinetic determination of traces of manganese(II) by its catalytic effect on the autoxidation of 1,4-dihydroxy phthalimide dithiosemicarbazone

A kinetic method is described for the determination of trace amounts of manganese(II) based on its catalytic effect on the aerial oxidation of 1,4-dihydroxyphthalimide dithiosemicarbazone. The reaction is followed spectrophotometrically by measuring the rate of change in absorbance at 594 nm. The calibration graph (rate constant vs. manganese concentration) is linear in the range 10–90 ng Mn ml^-1. The preparation and properties of the reagent are described and the kinetic parameters of the reaction are reported. There are few interferences.     

Spectrophotometric determination of maneb by ternary complex formation with PAR and CTAB

A rapid, simple, direct, and sensitive method has been developed for the determination of maneb (manganese ethylenebisdithiocarbamate) based on the formation of manganese-4-(2′-pyridylazo) resorcinol complex by a ligand displacement reaction, which is rendered water soluble by a cationic surfactant cetyltrimethylammonium bromide (CTAB) by the formation of an ion association complex. Beer's law is obeyed over the concentration range 0.08–2.4 μg/ml of the final solution at 500 nm in pH range 8–12. The molar absorptivity and Sandell's sensitivity are calculated to be 8.84 × 10⁴ l.mol⁻¹.cm⁻¹ and 0.003 μg/cm², respectively. The developed method has been applied to the determination of maneb in commercial formulations, synthetic mixture, grain samples and vegetables.     

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 (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 based on its catalytic effect on the oxidation of carminic acid by hydrogen peroxide

A highly sensitive spectrophotometric method is described for the determination of trace amounts of osmium(VIII), based on its catalytic effect on the oxidation of carminic acid by hydrogen peroxide. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of carminic acid at 540 nm after 3 min of mixing the reagents. The optimum reaction conditions were 1x10(-4) mol l(-1) carminic acid, 0.013 mol l(-1) hydrogen peroxide and pH 10 at 25 degrees C. By using the recommended procedure, the calibration graph was linear from 0.1 to 1.5 ng ml(-1) of osmium; the detection limit was 0.02 ng ml(-1); the RSD for five replicate determinations of 0.2-1.4 ng ml(-1) was in the range of 1.8-4.7%. The influence of several foreign ions on osmium determination were studied and the effect of interfering ions were removed by extracting osmium into isobuthyl methyl ketone and back extracting into sodium hydroxide solution.     

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 reaction rate method for the determination of osmium by its catalytic effect on the oxidation of gallocyanine by bromate

A simple kinetic spectrophotometric method was developed for the determination of osmium. The method is based on the catalytic effect of osmium as osmium tetroxide on the oxidation of gallocyanine by bromate at pH 7. The reaction is monitored spectrophotometrically by measuring the decreasing absorbance of gallocyanine at 620 nm by the fixed-time method. A detection limit of 0.01 ng/ml and linear calibration curve from 0.1 to 100 and from 100 to 1200 ng/ml Os(VIII) is reported. The relative standard deviation for 0.0100 microg/ml Os(VIII) is 0.8% (N = 10). The method is free from most interferences. Osmium in synthetic samples is determined by this method, with satisfactory results.