Determination of manganese(II) by a chemiluminescence reaction

Manganese(II) ( 1.5 ng/ml) is determined by measuring either of the two emission peaks given by alkaline oxidation of luminol. Several other metal ions, which enhance both emission peaks, are masked by cyanide ions.     

Contact angles in thin liquid films : III. Interaction forces in Newton black soap films

The interaction parameters of Newton black soap films stabilized by NaDS, as derived from contact angle experiments, have been interpretated in terms of the structure and the interaction forces in the films. From the film thickness and the difference between the surface excess of the salt in the film and at the bulk surface it is concluded that (a) the diffuse double-layer overlap in the film is practically complete; (b) the film only contains absorbed DS⁻ ions and an equal amount of Na⁺ counterions, but no salt; and (c) the double layer at the bulk surface is still partly diffuse. A model for the structure of the NB films is proposed according to which the adsorbed DS⁻ ions with their counterions form a two-dimensional square lattice at each film surface. It is found that the interaction free energy of the NB films can be explained by taking into account the electrostatic interactions between the discrete ions in the two opposing surface lattices. The model of the NB film is qualitatively in agreement with the experimental results of other workers.     

Electrochemical phase formation (ECPF) and macrogrowth Part II. Two-rate models

A general theory is evolved for a class of macrogrowth models which possess two independent growth-rates. Relations connecting growth-rates to growth geometry are established and some new growth forms are shown to result for models with passivation or diffusion-controlled rates. The corresponding potentiostatic responses, their small and large time behaviours and peak characteristics are obtained. Numerical transients are also presented. An empirical equation is derived as a special case and an earlier equation is corrected. An interesting stochastic result pertaining to nucleation events in the successive layers is proved.     

The composition of the evolved gases from the thermal decomposition of certain metal sulfates

By the use of TG—MS, the thermal dissociation of anhydrous CuSO₄ and Al₂(S0₄)₃ was found to proceed according to the reactions:

followed by the reactions:

No SO₃ was indicated in the dissociation of alunite. The sulfate ion appears to dissociate by at least two different mechanisms although the parameter which controls the mechanisms has not been elucidated.     

Analytical applications of picolinealdehyde salicyloylhydrazone: Spectrophotometric determination of nickel and zinc

With a view to the use of picolinealdehyde salicyloylhydrazone as analytical reagent, a study of the physical properties and chemical reactions of this substance has been carried out. It reacts with nickel (λ_max = 375 nm, ? = 3.9 × 10⁴M^?1cm^?1) or zinc (λ_max = 365 nm, ? = 4.8 × 10⁴M^?1cm^?1) to produce a yellow 1:2 complex in both cases. Spectrophotometric determinations of trace amounts of nickel and zinc have been established.     

Electrochemical behavior of 1-nitroso-2-naphthol in aqueous solutions: Evaluation of the rate constant for the intervening chemical step in an ece mechanism from stirred-mercury-pool chronoamperometric data

In aqueous solution 1-nitroso-2-naphthol is reduced to 1-amino-2-naphthol by an ECE mechanism. The homogeneous first-order rate constant for the chemical reaction of the intermediate can be evaluated with the aid of current-time data obtained during controlled-potential electrolysis with a stirred mercury-pool working electrode, using the Karp-Meites equation for the dependence of quantity of electricity on time, and is found to be equal to 1.1 ± 0.1₅ s^?1.     

The application of electrodeposition techniques to flameless atomic absorption spectrometry : Part IV. Separation and preconcentration on graphite

A new flameless atomic absorption technique for the determination of trace metals in a salt matrix is described. The elements to be determined are electrolyzed on to a graphite electrode, the exposed part of which is ground, and a portion of the graphite powder is finally analyzed directly by flameless atomic absorption in a graphite furnace. Many elements can be determined from a single electrochemical deposition. The graphite powder may also be stored for later control analysis. The effects of various experimental parameters are described. The method is applied to the determination of trace metals in commercial salts.     

Spectrophotometric determination of 2-amino-3H-phenoxazin-3-one as a colouring matter in o-aminophenol

A spectrophotometric method using 0.5M hydrochloric acid in methanol as solvent, has been used for the determination of 2-amino-3H-phenoxazin-3-one [APZ], occurring as a coloured impurity in o-aminophenol [OAP]. This impurity dissolves in the acid medium, giving a stable red solution which complies with Beer's law. The method can be applied to the determination of APZ in technical samples of OAP.     

Oxidations involving silver—IX : Oxidation of primary amines by silver(II) picolinate.

A re-examination of the oxidation of primary amines of the type R·CH₂NH₂ by silver(II) picolinate reveals that the major product is usually the nitrile RCN, rather than the aldehyde RCHO, as had been reported previously.⁴     

Electrochemical behavior of ellipticine derivatives: Part I. Oxidation of 9-hydroxy-ellipticine

The electrochemical one-electron oxidation of 9-hydroxy-ellipticinium cations at a platinum electrode has been examined with particular attention to the thermodynamic redox potential and to the dimerization rate of the radical species produced. Both the reactant and the product of the electrochemical reaction are strongly adsorbed at the solution/electrode interface. The initial step of the anodic process is a reversible electron transfer accompanied by a fast deprotonation; E^0′=900?53 pH mV vs. NHE. The resulting neutral radical dimerizes, the rate constant of the surface dimerization being ca. 2.5×10⁹ mol^?1 cm² s^?1.     

The quantitative determination of hydrated calcium sulphates in cement by use of self-generating atmosphere thermogravimetry

A method is described for the quantitative determination of hydrated calcium sulphates in cement by use of self-generating atmosphere thermogravimetry. The method is rapid and precise and can be applied (with a suitably modified sample container) with most thermogravimetric equipment.     

Trace element determination in environmental pollution: A kinetic method for mercury estimation

A method is developed for the estimation of mercury in trace concentrations by measuring spectrophotometrically its catalytic effect on the rate of substitution of p-nitrosodiphenylamine into hexacyanoferrate(II). Under the specified conditions the detection limit is found to be 2.0 x 10(-8)M relative standard deviation 1.4%. The effect of other ions is discussed.     

Influence of volatile hydride-forming elements on antimony determination by atomic-absorption spectrometry with hydride-generation

A study was undertaken to determine the interfering effects of arsenic, bismuth, germanium, lead, selenium, tin and tellurium on trace determination of antimony by atomic-absorption spectrometry with hydride-generation. A 1% NaBH(4) solution was used as reductant and a small amount of oxygen was added to the hydrogen produced, to support the combustion and atomization of SbH(3). The interference from selenium in the determination of antimony is removed if potassium iodide-ascorbic acid solution or copper sulphate is added to the sample solution. The interference of tin and tellurium can also be avoided by adding potassium iodide-ascorbic acid solution. A possible interference mechanism is discussed.