Tensammetric Wave Research Articles

Differential pulse and alternating current polarographic study of Mo(VI) in sulfuric acid solutions

The electrochemical behavior of Mo(VI) was studied by differential pulse and alternating current polarography. The effect of the addition of ionic surfactants on the first three peaks corresponding to the reduction of Mo(VI) to Mo(V) indicates that the Mo(VI) complexes giving the first two peaks and the thrid, are anionic and cationic respectively. A tensammetric wave was observed in the DP and ac polarograms of Mo(VI).

Alternating current polarographic determination of microgram amounts of iodide ion by means of the catalytic oxidation of 1-amino-2-naphthol-4-sulfonic acid

The catalytic oxidation of 1-amino-2-naphthol-4-sulfonic, acid proceeds quickly with microgram amounts of iodide in the presence of sodium chlorate at pH between 1.3 and 2.0. The oxidation product shows a sensitive tensammetric wave at potentials of about +0.03 V vs. SCE (pH 1.75), so that the catalytic reaction was applied for the determination of microgram amounts of iodide ion. The most suitable conditions of the pH range, the concentration of ANS and sodium chlorate, reaction temperature and standing are 1.3–2.0, 3 × 10 −4 M, 0.05 M, 50° C and 1 h respectively. Using the recommended procedure, iodide ion can be determined precisely in the concentration range 0.4–6.5 ng ml −1 with a relative error of about 3%. Interference of foreign species and the application to the determination of total iodine in river and sea water are described.

Tensammetric determination of microgram amounts of EDTA using a catalytic oxidation of 2-amino-4-methylphenol with vanadium

The catalytic oxidation of 2-amino-4-methylphenol proceeds rapidly with microgram amounts of vanadium in the presence of sodium chlorate. The oxidation product of this reagent shows a sensitive tensammetric wave at the potential about −0.45 V vs. SCE (pH 3.0). The oxidation reaction is intensively inhibited by EDTA according to the formation of a stable vanadium-EDTA complex. This inhibitory effect for the catalytic oxidation of 2-amino-4-methylphenol is applied to the determination of microgram amounts of EDTA. Using the procedure recommended, EDTA can be determined accurately in the concentration range between 0.015 and 0.29 μg ml −1. Interferences of foreign species are described.

Tensammetric determination of microgram amounts of vanadium by catalytic oxidation of o-aminophenol.

A tensammetric method is proposed for the determination of microgram amounts of vanadium, based on catalysis of the oxidation of o-aminophenol with sodium chlorate in acidic solution (pH 2.0). The oxidation product gives a very sensitive tensammetric wave; under optimum conditions, the wave-height is proportional to the concentration of va vanadium. From 0.2 to 3.0 μg of vanadium can be determined in a final volume of 50 ml. Mo(VI), W(VI), Mn(VII), Ce(IV) and large amounts of Al(III) and Fe(III) cause positive errors, and Hg(II) and thiosulphate negative errors. Interference from Fe(III), Al(III) and Cu(II) can be eliminated by solvent with oxine at about pH 8.0.

Determination of Copper by Catalysis of the Oxidation Reaction of O-Amino Phenol

Abstract The oxidative dimerization reaction of o-amino phenol with dissolved oxygen is catalyzed by the presence of an extremely small amount of copper(II) ion. In a. c. polarography, the oxidation product of o-amino phenol gives a very sensitive tensammetric wave in the pH range 5 to 9. This tensammetric wave is used for the determination of copper(II) ion from 0.3 to 3.5 μg/100 ml final solution.

Use of a Tensammetric Wave for the End-Point Detection in Chelatometry

Abstract A new method for the end-point detection in complexometric titration using a tensammetric wave of organic reagents such as oxine and alizarin complexone (ALC) was studied. The tensammetric wave of these reagents disappears by their chelate formation and reappears by the liberation of free indicator during the exchange reaction between indicator chelate and EDTA. This mechanism is utilized for the end-point detection in complexometric titration of metals. Since the sensitivity of tensammetric wave is extremely high, very sharp end-point can be obtained for the titration of metals even in the concentration of 10−5M.

A.C. Polarographic studies of oxine and its derivatives

Oxine and its derivatives, oxine-5-sulphonic acid, ferron, and 2-methyloxine, yield two a.c. waves at the positive region of the dropping mercury electrode. Wave I at more positive polarization, although ill-defined in the cases of oxine-5-sulphonic acid and ferron, is the so-called transition wave, and wave II at more negative potentials is a tensammetric wave. The height of wave II is dependent on pH, and the pH-region at which maximum wave height is obtained is specific to the compound, depending on its pk-value. Oxine and its derivatives can exist as three species according to the pH of the solution: i.e., acidic, neutral and basic forms. The neutral species of oxine, oxine-5-sulphonic acid and 2-methyloxine mainly contribute to wave II, while for ferron, both acidic and neutral species can contribute to wave II. The addition of certain metal ions that form chelates with oxine or its derivatives quantitatively depress wave II. This fact can be used to detect the end-point of titrations of metal ion in very dilute concentrations. The theoretical possibility of the titration has been considered.

Tensammetric Study of the Adsorption of Brucine

Abstract This paper will present two results of experiments concerning the adsorption of brucine. We will first discuss the adsorption of brucine on D. M. E. studied tensammetrically. Brucine was found to give a tensammetric wave with two peaks, at +0.10 V and −1.15 V vs. SCE. The positive tensammetric peak can be ascribed to the usual adsorption process. The second peak, however, behaved differently from the first, probably due to the reformation of adsorbed brucine film involving the protonation and the reorientation of brucine. Secondly, we will present experimental facts concerning the depressive effects of brucine on the reduction waves of copper(II).

On the Tensammetric Wave of Deoxycholic Acid

胆汁酸の一つであるデオキシコール酸のテンサンメトリー波について検討し, その挙動および前に報告したコール酸, デヒドロコール酸のそれとの比較検討を行なった。デオキシコール酸のテンサンメトリー波はコール酸の場合と同様, 吸着層の相分離に基づく二つの脱着波を示した。その原因は分子中に存在する水酸基が分子間でたがいに反発し合うために起ることが明らかとなった。一方デヒドロコール酸にはそのような現象はみられない。吸着過程についてもデヒドロコール酸が純粋な拡散支配であるのに反して, デオキシコール酸およびコ一ル酸は活性化吸藩過程を含んでいることがわかった。競争吸着については, 二者の脱着電位がたがいに接近しているもの同志では協調吸着しやすく, 離れているほど吸着力の強い方が独占的に吸着しやすくなる。またデオキシコール酸一メチルセルロ一ス系の場合のように, 両者が独立した吸着層を形成して, 両者が独立したテンサンメトリー波を示す場合もあることがわかった。

On the Reduction and Tensammetric Wave of Dehydrocholic Acid

On the Reduction and Tensammetric Wave of Dehydrocholic Acid

On the Tensammetric Waves of t-Amyl Alcohol(a)

Theory of tensammetry has been discussed on the basis of the kinetic theory of adsorp-tion at mercury-solution interface. (1) Tensammetric wave may be regarded as differential capacity vs. potential curve under a certain condition. Theoretical equations, relating the peak potential and the peak height to the bulk concentration, have been derived. (2) Adsorption phenomena and tensammetric wave of t-amyl alcohol have been ana-lyzed. Better agreement with the theoretical equation is obtained when the experimental results are analyzed for the positive and negative branches, separately. (3) The result are in harmony with the theoretical consideration. Parameters of ad-sorption equation have been calculated and discussed in view of Frumkin-Butler theory. Marked effect of anion on the tensammetric wave is understood by the present consideration.

A.C. POLARAPHY OF CYSTINE

A.C. polarography revealed that cystine yields a tensammetric wave, indicating adsorption at the mercury drop. The findings also indicate that the kinetic nature of the prestep seen in the D.C. polarograms, is due to reduction of adsorbed cystine molecules, adsorption being the rate determining process. The application of A.C. polarography makes it possible to study in detail the interaction of cystine molecules with surface films adsorbed at the electrode.

Alternating current polarography of organic compounds. III. Chloranilic acid

The behaviour of chloranilic acid at the dropping mercury electrode has been techniques of ordinary and of alternating current polarography. A new type of tensammetric wave has been encountered, which is probably an outcome either of multilayer adsorption and/or of a change in state of the adsorbed film. At the same time, a new tensammetric phenomenon, the exchange of one species of surface-active molecules against another, has been observed. Alternating current polarography can be used for estimating chloranilic acid at concentrations as low as 10-7M, whereas conventional polarography does not permit analysis at concentrations below 10-5M.