Studies in peroxidase action—XIV Intermediate compounds in the oxidation of p-toluidine

Previous work has shown that the peroxidation of p-toluidine gives a complex mixture of six products one of which is 4,4′-dimethyldiphenylamine. It has also been suggested² that4-methyl-N²-p-toly-o-phenylenediamine is an intermediate compound in the oxidation. Experiments have now been carried out to demonstrate that both these compounds are possible reaction intermediates.

It has also been established that the relative yields of the oxidation products depend upon the initial concentration of the p-toluidine. TLC and column chromatography have been extensively used in the separation and identification of the products.     

Spectrophotometric determination of palladium with 2,2′-diquinolyl ketoxime

Summary A visible Spectrophotometric method is described for the determination of palladium with 2,2-diquinolyl ketoxime. The effects due to p_H, time, solvents, reagent concentration and diverse ions are reported. Beer's law is obeyed and the molar extinction coefficient is 1.3·10⁴ at 478 nm. The incorporation of EDTA into the procedure results in a highly specific method for the determination of trace amounts of palladium.

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Zusammenfassung Die spektralphotometrische Bestimmung von Palladium mit 2.2-Dichinolylketoxim wurde beschrieben. Über den Einfluß von p_H, Zeit, Lösungsmitteln, Reagenskonzentration und von diversen Fremdionen wurde berichtet. Das Beersche Gesetz ist erfüllt. Der molare Extinktionskoeffizient beträgt bei 478 nm 1.3·10⁴. Die Einführung von ÄDTA in das Verfahren führt zu einer hochspezifischen Bestimmung von Palladiumspuren.

     

The solvent extraction and spectrophotometric determination of vanadium with 1-[(6-methyl-2-pyridyl) azo] -2-hydroxynaphthalene N-oxide

Summary The synthesis of the title reagent and its application to the spectrophotometric determination of traces of vanadium are described. The effects due to acidity, standing time, reagent concentration and diverse ions are reported. Beer's law is obeyed over the range 0.4–4.0 ppm and the molar extinction coefficient at 562 nm is 8000.

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Die Extraktion und spektrophotometrische Bestimmung von Vanadin mit 1-[(6-Methyl-2-pyridyl)azo]-2-hydroxynaphthalin-N-oxid

Zusammenfassung Die Synthese des genannten Reagens und seine Verwendung zur spektrophotometrischen Bestimmung von Vanadinspuren wurden beschrieben. Der Einfluß der Acidität, der Reaktionszeit, der Reagenskonzentration und verschiedener Fremdionen wurden beschrieben. Das Beersche Gesetz ist zwischen 0,4 und 4,0 ppm erfüllt, der molare Extinktionskoeffizient bei 562 nm beträgt 8000.

     

Pyridine ketoximes as analytical reagents: The spectrophotometric determination of gold with 2,2′-dipyridyl-α-glyoxime

Summary A Spectrophotometric method is described for the determination of gold with 2,2-dipyridyl--glyoxime. The effects due to p_H, solvents, reagent concentration, time, heating, ion-pair formation and diverse ions are reported. Beer's law is obeyed and the molar absorption coefficient is 1.7·10⁴].–M^–1.cm^–1 at 448 nm.

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Zusammenfassung Eine spektrophotometrische Goldbestimmung mit 2,2-Dipyridyl--gly-oxim wurde beschrieben. Der Einfluß von p_H, Lösungsmitteln, Reagenskonzentration, Zeit, Erwärmen, Ionenpaarbildung und diversen Fremdionen wurde angegeben. Das Beersche Gesetz ist gültig; der molare Absorptionskoeffizient bei 448 nm beträgt 1,7–10⁴ L.M^–1.cm^–1.

     

Determination of dissociation constants for a heparin-binding domain of amyloid precursor protein and heparins or heparan sulfate by affinity capillary electrophoresis

Dynamic affinity capillary electrophoresis (ACE) was used for determining the binding constants between heparin-like glycosaminoglycans and the (96-110) heparin-binding domain of amyloid precursor protein (APP). The migration time shift of the (96-110) APP peptide was monitored as the concentration of heparin was increased in the background electrolyte. The compounds investigated included low-molecular-weight heparin, porcine mucosa heparin, and heparan sulfate. Change in mobility as a function of glycosaminoglycan concentration was plotted using both linear regression (Scatchard analysis) and nonlinear regression. Dissociation constants (K(d)) were determined and compared for both sets of analyses with the low-molecular-weight heparin giving the most reproducible results and best fit with a K(d) value of 3.9 microM.     

Ion beam analyses of carbon nanotubes

The utility of ion beam analysis (IBA) techniques to quantitatively determine impurities in carbon nanotubes (CNTs) over a wide range of atomic numbers is demonstrated. Such techniques have not previously been used to monitor impurities and their effects in this unique material. Despite the difficulty in mounting the samples (which generally are formed into a powdery aggregate rather in a thin film), it is shown that reliable and accurate measurements of impurity concentrations can be achieved. Particle-induced X-ray emission (PIXE) and elastic recoil detection (ERD) analyses were used to characterize both metallic and very light (e.g., hydrogen) impurities in CNTs. This paper reports the first direct measurement of hydrogen in CNTs using an IBA technique. This is significant because CNTs are being actively investigated for hydrogen storage technology for energy applications.     

Liquid-liquid extraction with long-chain quaternary Ammonium Halides

The extraction of anionic chloro-complexes of certain metal ions using various long-chain quaternary ammonium halides in toluene and chloroform is described. The investigation has concerned itself mainly with coualt(II) and iron(III); a few extractions have also been carried out with indium(III) and gallium(in). The ion association of chloro-anionic complexes of iron, cobalt, indium and gallium in aqueous chloride media (hydrochloric acid or lithium chloride) with the quaternary ammonium ion in the organic phase is responsible for the extraction of the metal ion into the organic phase. Tlic extraction efficiency varies with the nature of the metal ion system involved as well as with the distribution of the quaternary compound and the size, shape and nature of the organic groups substituted in the quaternary compound.     

Alkyl ketoximes as analytical reagents. XVI

Summary The results of a study of the chloroform extraction of silver(I) from aqueous nitric acid and aqueous nitrate ion solutions, employing 4-heptanone oxime as a complexing agent are outlined.The effects of nitric acid, sodium nitrate, 4-heptanone oxime, and silver (I) concentrations are described. Two models of the extraction process are used to explain the distribution ratios obtained at low and high nitric acid and nitrate ion concentrations.Measurement of recovery factors indicate that greater than 99.9% of the silver(I) taken at the 5-mg level per 50 ml of aqueous phase can be extracted.

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Alkylketoxime als analytische Reagenzien. XVI

Zusammenfassung Die Extraktion von Silber(I) aus wäßriger Salpetersäure- und Nitrationenlösung bei Gegenwart von 4-Heptanon als Komplexbildner mit Chloroform als Extraktionsmittel wurde untersucht. Der Einfluß der verschiedenen Lösungspartner wurde beschrieben. Zwei Modelle des Extraktionsvorganges wurden herangezogen, um die Verteilung bei geringer und bei hoher Konzentration von Salpetersäure und Nitrationen zu erklären. Die Bestimmung der Ausbeutefaktoren zeigt, daß 5 mg Silber zu mehr als 99,9% aus 50 ml wäßriger Phase extrahiert werden.

     

High-performance liquid chromatographic assay with ultraviolet detection for the determination of etoperidone and two active metabolites, 5-(1-hydroxyethyl) etoperidone and 1-(3-chlorophenyl)piperazine, in plasma

A selective and sensitive high-performance liquid chromatographic assay with ultraviolet detection for the determination of the antidepressant drug etoperidone and two active metabolites in plasma is described. The drug, metabolites and internal standard are isolated from plasma using a two-step liquid-liquid extraction procedure. The resulting sample is chromatographed on a C18 column (10 cm x 2.1 mm I.D.) with ultraviolet detection at 254 nm. Standard curves are linear for each compound over the concentration range 2-1000 ng/ml. The accuracy and precision of the assay, expressed as the percentage deviation of measured values from the true value and the relative standard deviation (inter-run), are less than or equal to 10% at all concentrations except the minimum quantification limit. Using an automated injector and computerized data acquisition, eighty samples can be routinely processed in one day. The assay has been successfully used for the analysis of plasma samples from pharmacokinetic studies in mice, rats, dogs and humans.